Caterpillar SR4
Caterpillarengine - generator setgenerator

Caterpillar SR4

Maintenance schedule, common problems & OEM parts breakdown

The Caterpillar SR4 is a brushless, static-regulated synchronous generator end - not a complete engine-generator package. Cat documented it in the SEBU6150 operation and maintenance manual (revised 1994), an analog-era design using self-excited or permanent-magnet-pilot-excited fields with VR3 or VR4-family solid-state voltage regulators, offered in single-bearing and two-bearing frame constructions. Frame sizes span roughly the low 400s up through the 800-class, covering output from around 85 ekW to well over 1000 ekW standby depending on frame and lead configuration. Cat factory-paired the SR4 generator end to whichever engine matched the target rating and frame - gas G3306, and diesel 3208, 3306, 3406/3406C, 3408, 3412, and 3512 all show up on SR4-equipped sets - so there is no single fixed engine, weight, or chassis that defines the line.

The differences across SR4 configurations run through frame size, bearing arrangement, and lead/pole count rather than model years: four-, six-, ten-, or twelve-lead reconnectable stators, four- or six-pole rotors, and 50 Hz or 60 Hz windings let one basic architecture cover everything from small diesel standby sets to multi-megawatt plants. Cat carried the same brushless, self-excited/PME approach forward into the higher-output SR4B frames and later moved newer generator-end designs to digital voltage regulation. In the used and parts market today, SR4 value sits almost entirely in the generator end itself - stator and rotor windings, bearings, rotating rectifier, exciter, and voltage regulator - because surviving units get pulled from decommissioned gensets built around many different Cat engines and are resold or rebuilt as standalone generator ends rather than as intact machines.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Caterpillar SR4 specifications

Engine

Generator-end product typeSR4 is the alternator/generator-end line, not a fixed engine. It pairs with a range of Cat engines depending on the package; documented pairings span the gas G3306 (85-150 ekW class) up through diesel engines such as the 3306, 3406/3406C, 3408 and 3512 in larger frame sizes (up to roughly 1100 ekW standby, 687 frame).
Documented base pairing - G3306 gas engineI-6, 4-stroke-cycle, spark ignited, naturally aspirated or turbocharged-aftercooled
Bore x stroke (G3306)121 x 152 mm (4.75 x 6.0 in)
Displacement (G3306)10.5 L (638 cu in)
Compression ratio (G3306)8:1 (LCR / TA-130 configurations) or 10.5:1 (HCR / TA-90 configurations)
Power output (G3306 + SR4 set)85-150 ekW continuous at 1800 rpm, 60 Hz, 480 V, depending on NA/TA configuration
Larger diesel pairingsStandby ratings from about 180 ekW (446 frame) up to about 1100 ekW (687 frame) are documented on Cat diesel engines (3306/3406/3408/3512 family); full engine-side specs for those pairings belong to the individual engine, not the SR4 generator end
Emissions tierNot published for this legacy line - predates modern Tier/Stage emissions certification; verify current allowable use with your dealer

Weights

Shipping weight, G3306 NA set (85-100 ekW)1490 kg (3285 lb)
Shipping weight, G3306 TA-130 set (135 ekW)1531 kg (3375 lb)
Shipping weight, G3306 TA-90 set (150 ekW)1597 kg (3520 lb)
Generator-end weight, large frame (687 frame, ~1100 ekW standby)about 3175 kg (7000 lb) for the alternator alone, excluding engine
Ground pressureNot applicable - stationary package, no undercarriage

Dimensions

Overall length, G3306 NA / TA-130 set2263 mm (89.1 in)
Overall length, G3306 TA-90 set2352 mm (92.6 in)
Overall width, G3306 NA set818 mm (32.2 in)
Overall width, G3306 TA set978 mm (38.5 in)
Package height, NA configuration1269 mm (50.0 in)
Package height, TA configuration1210 mm (47.7 in)
Generator-end dimensions, large frame (687 frame)length 2007 mm (79 in), width 1245 mm (49 in), height 1600 mm (63 in), alternator only

Performance

Rated speed1800 rpm at 60 Hz; 1500 rpm at 50 Hz
Voltage regulationless than ±1%
Overspeed capability125%
Waveform deviationless than 5%
Telephone influence factor (TIF)less than 50
Total harmonic factor (THF)less than 3%
Voltage regulator type3-phase sensing with Volts-per-Hertz response, adjustable for engine speed droop and line loss compensation
Construction / excitationSingle bearing, close coupled, wye connected, static regulated brushless excited; Class F insulation, drip-proof enclosure, pilot-shaft alignment

Service capacities (summary)

Fuel tank, cooling system, engine oil capacitiesNot published as fixed figures in the SR4/G3306 factory package literature - cooling systems (radiator, heat exchanger, expansion tank), fuel systems and starting systems are listed as configurable/optional equipment rather than fixed capacities. Verify actual fitted capacity against the specific paired engine (G3306, 3306, 3406/3406C, 3408 or 3512) and cooling configuration with your dealer.

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

SR4 fluids & capacities

SystemCapacityRecommended fluid
Engine crankcase (with filter)Not fixed by the SR4 documentation. SR4 is a generator (alternator) end, not an engine, and is factory-paired with many different Caterpillar diesel or gas engines (3114/3116, 3204, 3208, 3304/3306, 3406, 3408/3412, 3508/3512/3516, D346/D348/D349, D353, D398/D399, or gas engines such as G3306, G342C, G379/G398/G399). Crankcase capacity with filter is set by whichever engine drives the set and is published in that engine's own Operation & Maintenance Manual, not in the SR4 generator manual.Cat Diesel Engine Oil (DEO) per the driving engine's own OMM, with viscosity grade selected from that engine's ambient-temperature chart. Gas-engine packages (e.g. G3306) use a natural gas engine oil per that engine's OMM rather than DEO.
Cooling system (jacket water)Not fixed by the SR4 documentation for the same reason — coolant capacity is a function of the driving engine's block/radiator/heat-exchanger arrangement and is published in that engine's OMM and general dimension drawing, not in the SR4 generator manual.Cat coolant/antifreeze (extended-life type) mixed per the driving engine's own climate table; exact product and concentration is set by that engine's OMM.
Fuel tankNot fixed by the SR4 documentation. Fuel system size depends on the base and skid supplied with the specific engine-generator package and whether the set is diesel or spark-ignited gas.Diesel fuel meeting Cat's diesel fuel specification for diesel-engine packages. For gas packages such as the G3306, pipeline natural gas is supplied at a minimum gas pressure specified on that engine's spec sheet; consult the driving engine's OMM for exact fuel-quality requirements.
Transmission / final drives / hydraulic system and tank / axlesNot applicable. The SR4 is a stationary generator (alternator) end close-coupled to an engine — it has no transmission, final drive, hydraulic system, or axle of its own.Not applicable.
Generator main bearing — shielded ball bearingSpec-only item (grease relubrication, not a fluid fill). Relubricate at roughly every 2000 service hours on prime/continuous units; standby units get bearing grease replaced about every three years.Cat Special Purpose Grease (SPG), the dealer-specified shielded-ball-bearing grade — NLGI No. 2 grade (without molybdenum disulfide), polyurea thickener, usable roughly -29 to 177 C (-20 to 351 F). Use NLGI No. 1 or 0 grade for extremely low ambient temperatures. Do not mix with the spherical-roller-bearing grease.
Generator main bearing — spherical roller bearing (larger frame sizes)Spec-only item (grease relubrication, not a fluid fill). Relubricate at roughly every 1000 service hours.the dealer-specified spherical-roller-bearing grease — NLGI No. 1-1/2 grade (without molybdenum disulfide), clay thickener, viscosity about 32 cSt at 40 C and 5 cSt at 100 C. Do not mix with the ball-bearing grease.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Caterpillar SR4 maintenance schedule

Service intervalTasks
Every 50 h
  • Walk around the generator end and driving engine; look for unusual noise, vibration, or overheating at the bearing bracket
  • Check that air inlet screens and enclosure louvers are clear of debris so cooling air reaches the windings
  • Listen for bearing noise and confirm output voltage holds steady under the voltage regulator's control
  • Feel or read bearing-bracket and main stator winding temperature and log the trend
Every 250 h
  • Wipe down exterior of the generator end; clean off accumulated oil film and dirt that can trap moisture against the windings
  • Check terminal box connections and lead lugs for tightness
  • Inspect anti-condensation space heater and thermostat operation if fitted
  • Visually confirm coupling/flywheel-housing alignment to the driving engine hasn't shifted
Every 500 h
  • Run a megohmmeter insulation-resistance check on the main stator winding and compare to the trend line
  • Inspect the rotating rectifier assembly and surge varistor for discoloration or drift
  • Retorque accessible mounting and coupling bolts to spec
  • Check the VR3/VR4 voltage regulator's gain and voltage-level adjustment against rated output
Every 1,000 h
  • Grease spherical roller bearings per the frame's charge and grease-type spec
  • Recheck bearing-bracket temperature trend against baseline
  • Inspect the brushless exciter armature and rotating fuses for heat discoloration
  • Verify insulation resistance again if the unit runs in a humid or exposed environment
Every 2,000 h
  • Grease shielded ball bearings on frames built with that bearing type
  • Run a full insulation-resistance and polarization-index check on the stator winding
  • Inspect the whole winding for hot spots, cracked varnish, or discoloration
  • Open the bearing bracket for inspection if noise or a low resistance trend was flagged earlier
Every 6,000 h
  • Treat this as a 3-year or major-engine-overhaul milestone rather than a strict hour count - whichever comes first
  • Pull the bearing bracket and inspect bore roundness, outer race condition, and rolling elements; replace bearing and full grease charge
  • Clean, dry, and revarnish stator and rotor windings if insulation resistance has trended low; rewind the exciter field or main armature if burned
  • Recheck and reset coupling alignment to the driving engine's flywheel housing before returning the end to service

Servicing the SR4 beyond the schedule

Predictive Maintenance & Fluid Analysis

The SR4 generator end carries no crankcase oil or coolant of its own - fluid sampling belongs to whichever Cat engine drives it, tracked in that engine's own OMM. On the generator side, predictive care means trending megohmmeter insulation-resistance readings on the main stator winding, logging bearing-bracket and winding temperatures at every check, and watching rotating-rectifier diode and varistor readings for early drift before a voltage regulator fault takes the set offline.

Corrective & Common Repairs

Recurring SR4 failures center on the brushless exciter and its rotating rectifier: burned exciter rotor fields, failed diodes or surge varistors, and VR3/VR4 regulator drift are the most common corrective jobs, alongside bearing-bracket noise from a worn outer race. Most electrical complaints trace back to a mechanical cause - loose terminal-box connections, a shifted coupling, or moisture-loaded windings - so check alignment to the driving engine's flywheel housing and stator insulation resistance before condemning the regulator or rectifier.

Overhaul & Rebuild Points

A full SR4 overhaul ties to the driving engine's major-overhaul interval rather than a separate schedule: pull the bearing bracket, inspect bore and outer race for out-of-roundness or fretting, and replace the bearing and grease charge. Low insulation-resistance readings call for cleaning, drying, and revarnishing the stator and rotor windings, or a rewind if the exciter field or main armature has burned. Recheck coupling alignment to the flywheel housing before returning the end to service.

Seasonal & Environment Servicing

Insulation-resistance testing frequency on the SR4 tracks environment, not a fixed calendar: weekly in seawater or high-humidity duty, quarterly for exposed or uncovered installations, and every six months for units in a dry enclosure. Before storage or a wet season, verify anti-condensation space heaters and their thermostats work, keep air inlet screens and louvers clear of dust, and clean oil and dirt film off the windings - trapped grime holds moisture against the insulation and speeds resistance loss.

SR4 common service parts

Part numberPart
6V-7615Film-Identification-On Fuel FilterCheck fitment →
101-7664FilmCheck fitment →
9Y-5036Filter As-RfiCheck fitment →
9Y-5037Filter As-RfiCheck fitment →
6I-3837Filter As-RfiCheck fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

SR4 fault codes & troubleshooting

CodeMeaningLikely causeWhat to do
HIGH WATER TEMPERATURE (shutdown lamp)Engine coolant temperature exceeded the safe shutdown setpoint; set shuts the unit down and lights the panel lamp.Low coolant level, blocked radiator/core, failed water pump or thermostat, or a faulty temperature sending unit.Let the set cool, check coolant level and look for leaks or a plugged radiator before attempting a restart.
LOW OIL PRESSURE (shutdown lamp)Engine lube oil pressure dropped below the protective trip point; engine shuts down and the lamp lights on the gauge panel.Low oil level, oil leak, worn or failing oil pump, or a bad pressure sending unit/switch.Check crankcase oil level and look for external leaks before restarting; verify sender if level and leaks are normal.
OVERSPEED (shutdown lamp)Engine speed exceeded the governor's overspeed trip point, tripping a mechanical/electrical shutdown.Governor or fuel linkage malfunction, sudden loss of load (breaker trip) with a sticking rack, or a failed speed-sensing circuit.Inspect governor linkage and fuel rack for binding, then verify speed sensor/wiring before restart.
FAIL TO START / OVERCRANKThe set did not start within the allotted number of crank cycles and the starting circuit locked out.Fuel supply interruption (air in lines, plugged filter), weak starting batteries, or a cold-start aid problem.Bleed fuel system and check filters, check battery state and starter engagement, reset lockout and retry.
EMERGENCY STOPThe remote or local emergency-stop circuit was tripped, shutting the set down and holding it in lockout.E-stop pushbutton actuated, or an open/short in the E-stop wiring loop.Confirm no E-stop button is latched, check the E-stop loop wiring, then reset before restarting.
OVERVOLTAGE (AVR/regulator trip)Generator terminal voltage rose above the regulator's protective band for the set trip time and the regulator dropped excitation.Voltage regulator (VR3/VR4-family) sensing lead fault, bad regulator, or an incorrect voltage/gain setting.Check AVR sensing leads and terminal connections, verify voltage adjustment, replace regulator if it will not hold setpoint.
UNDERVOLTAGE / LOSS OF EXCITATIONGenerator output voltage stayed below the regulator's minimum band, indicating the exciter/rotating-rectifier circuit is not building or holding field current.Blown regulator fuse, failed exciter diode or rotating-rectifier bridge connection, or a broken sensing lead.Check the AVR fuse first, then megger and inspect the rotating rectifier/diode assembly for open or shorted diodes.
OVEREXCITATION / OVERCURRENT SHUTDOWNExcitation or output current exceeded the regulator's protective threshold for the timed limit (or instantaneously above the trip level), and the regulator shut off output.Sustained overload, shorted stator or field winding, or a regulator protection-limit misadjustment.Remove load and check for a winding or wiring short before re-energizing; verify regulator protection settings against spec.

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

SR4 attachments & work tools

Engine pairing and output range

The SR4 is a generator end (alternator), not a standalone engine, and factory-paired with Caterpillar diesel engines across the 3208, 3306, 3406, 3408, 3412 and 3500-series lines depending on rating. Output spans roughly 85 ekW at the small end up to 500+ kW prime/continuous on the largest single-bearing builds, with two-bearing and larger-frame builds documented past 1000 kW; exact kW-per-engine pairing varies by configuration and era.

Frame size and bearing arrangement

Generator frames span roughly the 446 through 824 range depending on output and voltage class. Offered in single-bearing, close-coupled construction (rotor overhung on a flexible plate coupling bolted to the engine flywheel) or two-bearing construction for belt-driven or remote-mounted setups; frame-to-kW mapping varies by voltage and duty rating.

Voltage regulator options

Standard SR4 generators (excluding oil-field-arrangement units) ship with a factory voltage regulator selected from the VR1, VR2, VR3, VR3F and VR4 families. VR1/VR2 use epoxy-module construction with droop, level and gain potentiometers and a thermal-protector cutout; VR3/VR3F/VR4 use fused plus solid-state overcurrent protection, with VR4 omitting voltage droop and VR3F omitting gain adjustment.

Excitation system / PMG option

Base units are self-excited as standard. A permanent-magnet-generator (PMG) pilot-excitation option is offered, mounted on the non-drive end, supplying regulator power independent of residual magnetism so no field-flash is needed at start-up. This arrangement is associated with oil-field and remote-site generator packages built on the SR4 line.

Control panel and switchgear options

Units are offered from a basic start/stop and alarm-monitoring control panel up through paralleling-capable switchgear with 3-phase voltage sensing, adjustable voltage regulation (about ±1%), and volts-per-hertz response for load-sharing between sets. Full multi-unit paralleling and synchronizing switchgear is a factory or dealer-added package rather than a base-unit feature, and scope varies by configuration.

Circuit breaker and output protection

A generator-mounted output circuit breaker is offered as an option sized to the unit's full rated output, with sensing and isolation transformers for paralleling installations. An RFI/EMC filter option is documented for units built to European electromagnetic-compatibility standards; breaker and filter scope varies by series and destination market.

Enclosure and weather protection

A factory or dealer-installed weatherproof, sound-attenuated enclosure is offered on a fabricated steel skid base, with an internally mounted exhaust silencer reducing noise by roughly 25 dBA. Construction uses stainless or zinc-plated hardware and modular, field-repairable panels for outdoor and job-site duty; this is an add-on package, not part of the base open-set generator.

All SR4 assemblies by section

Every catalogued assembly group for the Caterpillar SR4. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Air Inlet And Exhaust System
4w9079 Air Cleaner Gp
6i2572 Air Cleaner Gp
7e6071 Air Cleaner Gp
4w1657 Air Cleaner Gp
8n4670 Air Cleaner Gp
4w1658 Air Cleaner Gp
1w0540 Muffler Gp
0S***71Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting2
0S***94Bolt--Lifting Eye To Cylinder Head2
1D***17Nut-Plate And Angle Assembly To Hydraulic And Fuel Tanks; Nut Plate And Angle Assembly To Hydraulic And Fuel Tanks2
See all parts with full part numbers in Heavy Parts AI →
4w0877 Muffler Gp-With Rain Caps
4w2089 Exhaust Extension Gp
2w5219 Exhaust Fitting Gp-76 Mm (3 In.)-Flexible
5n9577 Exhaust Fitting Gp-76 Mm (3")
1w8822 Exhaust Flange Gp-76 Mm (3")
2w5226 Exhaust Flange Gp-76 Mm (3 In.)
2n3322 Gauge Gp-Air Cleaner
2N***22Gauge Group-Air Cleaner; Air Filter Indicator Group1
See all parts with full part numbers in Heavy Parts AI →
9n0735 Positive Crankcase Ventilation Lines Gp
9N***35Lines Group-Pcv; Positive Crankcase Ventilation Valve Group1
See all parts with full part numbers in Heavy Parts AI →
7n5198 Manifold Gp-Exhaust
9n0555 Inlet Manifold Gp
9N***55Manifold Group-Inlet; Inlet Manifold Group1
See all parts with full part numbers in Heavy Parts AI →
1n4746 Exhaust Pipe Gp-90 Degrees
2w5223 Exhaust Pipe Gp-76 Mm (3 In.)
4m0310 Precleaner Assembly
4h5076 Precleaner Gp
1217746 Precleaner As
9l8790 Valve As
7c6353 Valve As
Basic Engine
9n0728 Camshaft Gp
9N***28Camshaft Group-Single; Camshaft Group1
See all parts with full part numbers in Heavy Parts AI →
9l6065 Cylinder Block Cover Gp
9L***65Cover Group-Cylinder Block; Cylinder Block Cover Group1
See all parts with full part numbers in Heavy Parts AI →
9l7861 Flywheel Housing Cover Gp
9L***61Cover Group-Flywheel Housing; Flywheel Housing Cover Group1
See all parts with full part numbers in Heavy Parts AI →
4w6972 Cover Gp-Valve Mechanism
9n0730 Valve Mechanism Cover Gp
9N***30Cover Group-Valve Mechanism; Valve Mechanism Cover Group1
See all parts with full part numbers in Heavy Parts AI →
4w6968 Cover Gp-Valve Mechamism
4w6968 Cover Gp-Valve Mechanism
Crankshaft Bearing Replacements
8N***71.51 mm--Front Main--Non-Grooved1
8N***72.51 mm--Front Main--Non-Grooved1
8N***730 Standard--Front Main--Non-Grooved; 0 (Standard)-Front Main-Non-Grooved1
See all parts with full part numbers in Heavy Parts AI →
9n6222 Crankshaft Gp
2w0085 Crankshaft Gp*R
9n3761 Cylinder Block Gp-Type 2
9N***61Cylinder Block Group; Cylinder Block Group1
See all parts with full part numbers in Heavy Parts AI →
9n3761 Cylinder Block Gp-Type 1
9N***61Cylinder Block Group; Cylinder Block Group1
See all parts with full part numbers in Heavy Parts AI →
7c3807 Cylinder Head As
7c2295 Head As-Cylinder Service*R
7c2296 Cylinder Head As
1w4241 Cylinder Head Gp*R
9n1105 Cylinder Head Gp*R
9N***05Cylinder Head Group; Cylinder Head Group1
See all parts with full part numbers in Heavy Parts AI →
Cylinder Head Valve Guides
4W***78Guide-Inlet Valve; Valve Guide-Inlet0
4W***79Valve Guide-Exhaust0
See all parts with full part numbers in Heavy Parts AI →
1w6897 Pulley And Damper Gp
1W***97Damper & Pulley Group; Pulley And Damper Group1
See all parts with full part numbers in Heavy Parts AI →
1w6897 Pulley & Damper Gp
1W***97Damper & Pulley Group; Pulley And Damper Group1
See all parts with full part numbers in Heavy Parts AI →
1w6784 Engine Ar-Part 2 Of 2
1W***84Engine Ar1
1W***06Pump Group-Gov & Fuel Inj; Governor & Fuel Injection Pump Gp1
2W***24Water Pump0
See all parts with full part numbers in Heavy Parts AI →
1w6784 Engine Ar-Part 1 Of 2
1W***06Pump Group-Engine Oil1
1W***38Filter Group-Engine Oil1
1W***38Housing Group-Flywheel1
See all parts with full part numbers in Heavy Parts AI →
4n8850 Flywheel Gp
1w3838 Housing Gp-Flywheel
1w8950 Flywheel Housing Gp
1w3838 Flywheel Housing Gp
7c6032 Housing Gp-Flywheel
9n5211 Housing Gp-Front
9N***11Housing Group-Front; Front Housing Group1
See all parts with full part numbers in Heavy Parts AI →
1w6714 Lifting Gp
4n6808 Lifting Gp
8n9558 Engine Mounting Gp
9n6314 Pan Gp-Oil
9N***14Pan Group-Oil; Pan Gp-Engine Oil1
See all parts with full part numbers in Heavy Parts AI →
9n6314 Oil Pan Gp
9N***14Pan Group-Oil; Pan Gp-Engine Oil1
See all parts with full part numbers in Heavy Parts AI →
9n6435 Connecting Rod & Piston Group-8 Required
9n6435 Rod & Piston Gp
2w4841 Piston Gp
4w8269 Piston Ring Gp--1.02 Mm (.040 In.) Oversize
2W***17Ring-Piston; (Oil)(1.02-mm Os)1
4W***68Ring-Piston; (Top)1
4W***69Ring Group-Piston1
See all parts with full part numbers in Heavy Parts AI →
4w8261 Ring Gp-Piston--.51 Mm (.020 In.) Oversize
2W***16Ring-Piston; (Oil)(0.51-mm Os)1
4W***60Ring--Top1
4W***61Ring Group-Piston1
See all parts with full part numbers in Heavy Parts AI →
9n0542 Seal Gp-Crankshaft
9N***42Seal Group-Crankshaft; Crankshaft Seal Group1
See all parts with full part numbers in Heavy Parts AI →
9n3763 Cylinder Block Service Gp
9L***65Cover Group-Cylinder Block; Cylinder Block Cover Group1
9N***61Cylinder Block Group; Cylinder Block Group1
9N***63Service Group-Cylinder Block1
See all parts with full part numbers in Heavy Parts AI →
2w7538 Engine Support Gp-Rear
1w6465 Engine Support Gp-Front
9n6428 Engine Support Gp
9n0487 Valve Mechanism Gp
9N***87Valve Mechanism Group; Valve Mechanism Group1
See all parts with full part numbers in Heavy Parts AI →
Cooling System
1083882 Base Gp-Oil Cooler & Filter
7w1764 Base Gp-Oil Cooler & Filter
1w7526 Cooler Gp-Engine Oil
9n0729 Oil Cooler Gp
7n7613 Drive Gp-Water Pump
7N***13Drive Group-Water Pump; Water Pump Drive Group1
See all parts with full part numbers in Heavy Parts AI →
1w2966 Fan Gp-Blower-22" (559 Mm)
2n2858 Blower Fan Gp-4 Blades
7c5086 Guard Gp-Radiator
7w5183 Guard Gp-Radiator
7c9005 Heater Gp-Jacket Water
7c7710 Heater Gp-Jacket Water
7C***10Heater Group-Jacket Water1
9Y***79Thermostat1
See all parts with full part numbers in Heavy Parts AI →
7e6250 Heater Gp-Jacket Water
7c9004 Heater Gp-Jacket Water
4w1432 Lines Gp-Drain-Coolant
9n0733 Water Lines Gp
9N***33Lines Group-Water; Water Lines Group1
See all parts with full part numbers in Heavy Parts AI →
9y5937 Mounting Gp-Jacket Water Heater
9Y***37Mounting Group-Jacket Wtr Heater1
See all parts with full part numbers in Heavy Parts AI →
7c7706 Mounting Gp-Jacket Water Heater
7C***06Mounting Group-Jacket Wtr Heater1
See all parts with full part numbers in Heavy Parts AI →
4w2673 Mounting Gp-Jacket Water Heater-Type 1
4W***73Mounting Group-Jacket Wtr Heater1
See all parts with full part numbers in Heavy Parts AI →
4w2673 Mounting Gp-Jacket Water Heater-Type 2
4W***73Mounting Group-Jacket Wtr Heater1
See all parts with full part numbers in Heavy Parts AI →
9n3654 Water Pump Gp
9N***54Pump Group-Water; Water Pump Group1
See all parts with full part numbers in Heavy Parts AI →
1w6450 Radiator Gp
1w6467 Radiator Gp
7w7526 Radiator Gp
Fuel System And Governor
7e8396 Solenoid Gp-Control
3T***70Relay As-24 Volt; (24 Volt)1
4W***90Block-Fuse1
7E***96Control Group-Fuel; -Auxiliary1
See all parts with full part numbers in Heavy Parts AI →
9l6743 Governor Control Gp
9L***43Control Group-Governor; Governor And Control Group1
See all parts with full part numbers in Heavy Parts AI →
3n7815 Governor Control Gp-Positive Lock
4w3728 Governor Control Gp-Positive Lock
1060447 Control Gp-Voltage-Manual
5n9174 Governor Control Gp-12 Volt Dc Relay
5n9175 Control Gp-32 Volt Dc Relay
6n0805 Drive Gp-Governor & Fuel Injection Pump
6N***05Drive Group-Governor & Fuel Pump1
See all parts with full part numbers in Heavy Parts AI →
9l6925 Fastener Gp-Fuel Pump Housing
9L***25Fastener Group-Fuel Pump Housing; Fuel System Fastener Group1
See all parts with full part numbers in Heavy Parts AI →
4n5868 Filter Gp-Fuel
4N***68Filter Group-Fuel; Fuel Filter Group1
See all parts with full part numbers in Heavy Parts AI →
8n5642 Governor & Fuel Injection Pump Gp-Part 1 Of 5
8n5642 Governor & Fuel Injection Pump Gp-Part 5 Of 5
8n5642 Governor & Fuel Injection Pump Gp-Part 3 Of 5
8n5642 Governor & Fuel Injection Pump Gp-Part 2 Of 5
8n5642 Governor & Fuel Injection Pump Gp-Part 4 Of 5
4p2788 Governor As
5n9237 Flexible Fuel Lines Gp-Type 2
5n9237 Flexible Fuel Lines Gp-Type 1
4w1143 Lines Gp-Fuel
9n0552 Fuel Filter Lines Gp
9N***52Lines Group-Fuel Filter; Fuel Filter Lines Group1
See all parts with full part numbers in Heavy Parts AI →
4w5799 Lines Gp-Fuel Injection
9n3880 Lines Gp-Fuel Injection-Part 2 Of 2
9n3880 Lines Gp-Fuel Injection
4w5800 Lines Gp-Fuel Injection
4W***00Lines Group-Fuel Injection; Fuel Injection Lines Group1
See all parts with full part numbers in Heavy Parts AI →
9y0300 Lines Gp-Fuel Injection
9y0301 Lines Gp-Fuel Injection
2w3398 Lines Gp-Fuel Injection
9n3880 Lines Gp-Fuel Injection-Part 1 Of 2
4w5798 Lines Gp-Fuel Injection
7w1998 Lines Gp-Fuel Injection
7W***98Lines Group-Fuel Injection; Fuel Injection Lines Group1
See all parts with full part numbers in Heavy Parts AI →
2w0770 Lines Gp-Fuel Injection
4n4314 Pump Gp-Fuel Priming
4N***14Pump Group-Fuel Priming; Fuel Priming Pump Group1
See all parts with full part numbers in Heavy Parts AI →
9y0509 Governor & Fuel Injection Pump Gp-Part 2 Of 5
4w5641 Governor & Fuel Injection Pump Gp-Part 1 Of 5
4w5641 Governor & Fuel Injection Pump Gp-Part 5 Of 5
9y0511 Pump Gp-Governor & Fuel Injection*R
8M***61Seal (Tachometer Drive Adapter To Cover)1
8M***57Seal-Governor Housing To Cylinder Block1
9L***30Gasket-Cross Over Pipe2
See all parts with full part numbers in Heavy Parts AI →
9y0512 Pump Gp-Governor & Fuel Injection
9Y***12Pump Group-Gov & Fuel Inj; Governor & Fuel Injection Pump Gp1
See all parts with full part numbers in Heavy Parts AI →
4w5619 Governor & Fuel Injection Pump Gp
4W***19Pump Group-Gov & Fuel Inj; Governor & Fuel Injection Pump Gp1
See all parts with full part numbers in Heavy Parts AI →
1w6806 Governor & Fuel Injection Pump Gp
1W***06Pump Group-Gov & Fuel Inj; Governor & Fuel Injection Pump Gp1
See all parts with full part numbers in Heavy Parts AI →
4w5641 Governor & Fuel Injection Pump Gp-Part 2 Of 5
9y0509 Governor & Fuel Injection Pump Gp-Part 3 Of 5
4w5641 Governor & Fuel Injection Pump Gp-Part 3 Of 5
4w5620 Governor & Fuel Injection Pump Gp
9y0505 Governor & Fuel Injection Pump Gp
9Y***05Pump Group-Gov & Fuel Inj; Governor & Fuel Injection Pump Gp1
See all parts with full part numbers in Heavy Parts AI →
9y0509 Governor & Fuel Injection Pump Gp-Part 4 Of 5
9y0509 Governor & Fuel Injection Pump Gp-Part 1 Of 5
1w6805 Governor & Fuel Injection Pump Gp
9y0509 Governor & Fuel Injection Pump Gp-Part 5 Of 5
9y0506 Governor & Fuel Injection Pump Gp
4w5641 Governor & Fuel Injection Pump Gp-Part 4 Of 5
4w1142 Water Separator Gp
4w6848 Separator Gp-Water
2w1408 Separator Gp-Water
9n5621 Water Separator Gp-Type 1
9n5621 Water Separator Gp-Type 2
2w4885 Fuel Tank & Base Gp
2w7906 Fuel Tank & Base Gp
6n0509 Torque Control Gp
Gauges And Accessories
1303332 Control Gp-Alarm Module
1303333 Control Gp-Alarm Module
13***33Control Group-Alarm Module; (Custom)1
See all parts with full part numbers in Heavy Parts AI →
9w3577 Control Gp-Electronic Remote 99*R
9w3577 Control Gp-Electronic-Remote 99*R
7w5993 Drive Gp-Tachometer
8m7892 Ammeter Gauge Gp
5n9076 Magnetic Pickup Gp
7w3354 Magnetic Pickup Gp
4w0771 Meter Gp-Hour
6n0224 Meter Gp-Hour
2w8912 Hour Meter Gp
6n0224 Hour Meter Gp-Type 1
5n9235 Hour Meter Gp
7c5024 Mounting Gp-Circuit Breaker
7l4535 Tachometer Mounting Gp
7L***35Mounting Group-Tachometer; Tachometer Mounting Group[[751
See all parts with full part numbers in Heavy Parts AI →
7c5296 Panel Gp-Instrument
5n9352 Panel Gp-Instrument-Part 1 Of 2
7c5130 Panel Gp-Instrument
4w9833 Instrument Panel Gp
7c3085 Panel Gp-Instrument
5n9352 Panel Gp-Instrument-Part 2 Of 2
5n9351 Panel Gp-Instrument
7w7011 Instrument Panel Gp-24 Volt-Automatic Start-Stop
1311963 Panel Gp-Instrument
1311962 Panel Gp-Instrument
2w8918 Magnetic Pickup Assembly
2W***18Sensor Group-Speed; -Engine Timing1
See all parts with full part numbers in Heavy Parts AI →
9w1077 Switch As-Start
9g1480 Switch Gp-Starter
5n9035 Electric Tachometer Gp
7e3158 Tachometer Gp-Electric
Generators
1044393 Circuit Breaker Gp
1044391 Circuit Breaker Gp
1044379 Circuit Breaker Gp
1044380 Circuit Breaker Gp
1130834 Circuit Breaker Gp
1130833 Circuit Breaker Gp
1044381 Circuit Breaker Gp
1044386 Circuit Breaker Gp
1044382 Circuit Breaker Gp
1044378 Circuit Breaker Gp
1044383 Circuit Breaker Gp
1044392 Circuit Breaker Gp
1044389 Circuit Breaker Gp
1044390 Circuit Breaker Gp
1044387 Circuit Breaker Gp
1044384 Circuit Breaker Gp
1044394 Circuit Breaker Gp
1044388 Circuit Breaker Gp
1044385 Circuit Breaker Gp
7w0571 Generator Leads Connection Gp
7W***71Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
4p5534 Connection Gp-Generator Leads
4P***34Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
5n4124 Generator Leads Connection Gp
5N***24Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
7w0574 Connection Gp-Generator Leads
7W***74Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
4p7148 Connection Gp-Generator Leads
4P***48Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
4p7150 Connection Gp-Generator Leads
4P***50Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
7w0115 Connection Gp-Generator Leads-2 Required-Type 1
7W***15Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
7w0572 Generator Leads Connection Gp
7W***72Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
7w0115 Connection Gp-Genereator Leads- 2 Required-Type 2
7W***15Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
1031839 Connection Gp-Generator Leads
10***39Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
7c1781 Connection Gp-Generator Leads
5P***75Washer-Hard; (10.2x22.5x3-mm Thk)(Shield To A/C)3
6V***01Nut; (3/8-16-Thd)(Plate To Rh And Lh Bracket As)2
7C***81Connection Group-Generator Leads1
See all parts with full part numbers in Heavy Parts AI →
5n4123 Connection Gp-Generator Leads
5N***23Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
7c1846 Connection Gp-Generator Leads
5P***75Washer-Hard; (10.2x22.5x3-mm Thk)(Shield To A/C)3
7C***46Connection Group-Generator Leads1
8L***95Nut-Full; (Cadmium)2
See all parts with full part numbers in Heavy Parts AI →
9y3845 Module As-Boost
7c2700 Module-Control-Manual Voltage
7c1600 Regulator As-Automatic Voltage
149-6130 Regulator As-Automatic Voltage
9y8400 Regulator As-Automatic Voltage
1078517 Switch As
9y0359 Transformer Gp-Current-Series Boost
3E***23Bolt-Flange Head; (1/4-20x1-In)2
5S***03Nut-Full; (5/16 X 18 Thd)2
8T***23Bolt-Head Locking; (5/16-18 X 1.0 In)2
See all parts with full part numbers in Heavy Parts AI →
4p3847 Transformer Gp-Current
9y3857 Transformer Gp-Current
9y2940 Transformer Gp-Current
4p9904 Transformer Gp
7c6849 Transformer Gp-Current
7w1616 Transformer Gp-Current
9y3839 Transformer Gp
9y3883 Transformer Gp-Current-Series Boost
5S***03Nut-Full; (5/16 X 18 Thd)4
8T***23Bolt-Head Locking; (5/16-18 X 1.0 In)4
9M***74Washer-Hard; (8.8x16x2-mm Thk)(Hard)4
See all parts with full part numbers in Heavy Parts AI →
1057185 Wiring Gp
2w0967 Engine Base Gp-Electric Set
2w7904 Engine Base Gp
2w0622 Engine & Generator Base Gp-Lightweight Skid
4p3909 Box Gp-Extension Terminal
1073057 Box Gp-Extension Terminal
1073056 Box Gp-Extension Terminal
3n5545 Box Gp-Extension Terminal
3n6710 Box Gp-Extension Terminal-Rh Mounted
1073055 Box Gp-Extension Terminal
3n5566 Box Gp-Generator Connection
3n5938 Box Gp-Generator Connection
4w8145 Chart-Circuit Breaker-Part 4 Of 5
4w8145 Chart-Circuit Breaker-Part 5 Of 5
4w8145 Chart-Circuit Breaker-Part 3 Of 5
4w8145 Chart-Circuit Breaker-Part 2 Of 5
4w8145 Chart-Circuit Breaker-Part 1 Of 5
1038974 Connection Gp-Electrical
4p4635 Connection Gp-Electrical
4w8981 Connection Gp-Terminal Strip
4W***81Connection Group-Terminal Strip1
See all parts with full part numbers in Heavy Parts AI →
4p7152 Connection Gp-Terminal Strip
4P***52Connection Group-Terminal Strip1
See all parts with full part numbers in Heavy Parts AI →
4w7405 Connection Gp-Terminal Strip
4W***05Connection Group-Terminal Strip1
See all parts with full part numbers in Heavy Parts AI →
7w1690 Connection Gp-Terminal Strip
7W***90Connection Group-Terminal Strip1
See all parts with full part numbers in Heavy Parts AI →
4w9994 Connection Gp-Terminal Strip
4W***94Connection Group-Terminal Strip1
See all parts with full part numbers in Heavy Parts AI →
5n1613 Control Gp-Manual Voltage
5N***13Control Group-Voltage-Manual1
5N***89Wiring Diagram And Installation Instructions1
5N***23Manual Voltage Control Assembly1
See all parts with full part numbers in Heavy Parts AI →
1093320 Coupling Gp-Generator
5n9166 Coupling Gp-Generator
1003028 Coupling Gp-Generator
3n6713 Cover As-Extension Box
6i4453 Cover Gp-Protective
5n0617 Generator Set Enclosure Gp
4w8378 Fastener Gp
4w8379 Fastener Gp
7w1689 Fastener Gp
7w1688 Fastener Gp
1061771 Fastener Gp-Extension Box
9y5036 Filter As-Rf1
9y5037 Filter As
6i3837 Filter As-Rfi
7w8745 Generator Ar
7W***72Connection Group-Generator Leads; Generator Leads Connection Group1
7W***43Generator Group; Generator Group1
7W***45Generator Ar1
See all parts with full part numbers in Heavy Parts AI →
5n9144 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
5N***23Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
5n9142 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
1W***56Plate-Information (Generator)1
2K***19Drive Screw--For Mounting Name Plate6
See all parts with full part numbers in Heavy Parts AI →
5n9148 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
1W***57Name Plate1
2K***19Drive Screw--For Mounting Name Plate6
See all parts with full part numbers in Heavy Parts AI →
1093767 Generator Ar
10***66Generator Group1
10***67Generator Ar1
1W***48Plate-Serial Number On Upper R.H.Side Of1
See all parts with full part numbers in Heavy Parts AI →
5n9147 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
5N***23Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
4w8970 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
4W***33Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w8959 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
4W***54Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w9665 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
4W***65Generator Ar1
See all parts with full part numbers in Heavy Parts AI →
5n9145 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
1W***56Plate-Information (Generator)1
2K***19Drive Screw--For Mounting Name Plate6
See all parts with full part numbers in Heavy Parts AI →
1093352 Generator Ar
10***52Generator Ar1
10***94Generator Group; Generator Gp-Power1
6I***53Cover Group-Protection1
See all parts with full part numbers in Heavy Parts AI →
1093793 Generator Ar
10***92Generator Group1
10***93Generator Ar1
1W***48Plate-Serial Number On Upper R.H.Side Of1
See all parts with full part numbers in Heavy Parts AI →
6i0052 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
4W***38Film - Earth Ground Symbol1
6I***52Generator Ar1
See all parts with full part numbers in Heavy Parts AI →
7w7520 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
7W***96Plate-Information; (Generator Information)(Generator Nameplate)1
See all parts with full part numbers in Heavy Parts AI →
4w9660 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
4W***83Generator Group1
See all parts with full part numbers in Heavy Parts AI →
5n9141 Generator Ar
1W***48Plate-Serial Number On Upper R.H.Side Of1
2K***19Drive Screw--For Mounting Name Plate6
5N***23Connection Group-Generator Leads; Generator Leads Connection Group1
See all parts with full part numbers in Heavy Parts AI →
9y0416 Generator Ar
6I***53Cover Group-Protection1
7W***71Connection Group-Generator Leads; Generator Leads Connection Group1
9Y***58Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w0183 Generator Gp-Side View-Part 1 Of 2
5n9081 Generator Gp-3 Phase-Side View-Part 1 Of 2
5N***81Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w8954 Generator Gp-End View
4W***54Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w8954 Generator Gp-End View-Part 2 Of 2
4W***54Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
7w8743 Generator Gp-Power-Part 2 Of 2
7W***43Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
5n9084 Generator Gp-3 Phase-End View-Part 2 Of 2
5N***84Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w0183 Generator Gp-Part 1 Of 2
4w9669 Generator Gp-End View-Part 2 Of 2
4W***69Generator Group; Generator Group-Power1
See all parts with full part numbers in Heavy Parts AI →
9y0358 Generator Gp
5n9088 Generator Gp-3 Phase-End View-Part 2 Of 2
5n9087 Generator Gp-3 Phase-End View-Part 2 Of 2
5N***87Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
5n9085 Generator Gp-3 Phase-End View-Part 2 Of 2
7w7521 Generator Gp-Power-Part 2 Of 2
5n9081 Generator Gp-3 Phase-End View-Part 2 0f 2
5N***81Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
5n9087 Generator Gp-3 Phase-Side View-Part 1 Of 2
5N***87Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
1093766 Generator Gp
1093394 Generator Gp
10***94Generator Group; Generator Gp-Power1
See all parts with full part numbers in Heavy Parts AI →
5n9084 Generator Gp-3 Phase-Side View-Part 1 0f 2
5N***84Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
5n9085 Generator Gp-3 Phase-Side View-Part 1 Of 2
6i0053 Generator Gp
5n9082 Generator Gp-3 Phase-Side View-Part 1 Of 2
5n9082 Generator Gp-3 Phase-End View-Part 2 Of 2
4w7433 Generator Gp-Power-Part 2 Of 2
5n9084 Generator Gp-3 Phase-Side View-Part 1 Of 2
5N***84Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w7433 Generator Gp-Power-Part 1 Of 2
4w0183 Generator Gp-Part 2 Of 2
4w9669 Generator Gp-Part 1 Of 2
4W***69Generator Group; Generator Group-Power1
See all parts with full part numbers in Heavy Parts AI →
4w8954 Generator Gp-Side View-Part 1 Of 2
4W***54Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w0183 Generator Gp-End View-Part 2 Of 2
1093792 Generator Gp
7w8743 Generator Gp-Power-Part 1 Of 2
7W***43Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w9669 Generator Gp-Side View-Part 1 Of 2
4W***69Generator Group; Generator Group-Power1
See all parts with full part numbers in Heavy Parts AI →
5n9088 Generator Gp-3 Phase-Side View-Part 1 Of 2
7w7521 Generator Gp-Power-Part 1 Of 2
4w9669 Generator Gp-Part 2 Of 2
4W***69Generator Group; Generator Group-Power1
See all parts with full part numbers in Heavy Parts AI →
5n9081 Generator Gp-3 Phase-End View-Part 2 Of 2
5N***81Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
7w8743 Generator Gp-Part 1 Of 2
7W***43Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w7433 Generator Gp-Side View-Power-Part 1 Of 2
7w8743 Generator Gp-Part 2 Of 2
7W***43Generator Group; Generator Group1
See all parts with full part numbers in Heavy Parts AI →
4w7433 Generator Gp-End View-Power-Part 2 Of 2
5n0654 Exciter & Heat Sink Assembly
3n5718 Holder-Lamp
5n9079 Generator Installation Ar
0S***91Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***8212
0T***20Bolt (1.25 In. Long X .438 In. Dia.)12
5M***94Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler12
See all parts with full part numbers in Heavy Parts AI →
9y0968 Kit-Filter-Rfi
9y2968 Kit-Space Heater
7w9653 Heater Kit-Space
7c0554 Heater Kit-Space
7w9833 Transformer Kit-Isolation
2w5418 Package Generator Set Lifting Gp
9y1711 Module As-Series Boost
6i3836 Module As-Boost
2w1791 Pre-Alarm Module Gp
9y8051 Mounting Gp-Circuit Breaker
7e1160 Mounting Gp-Circuit Breaker
4w8214 Circuit Breaker Mounting Gp
4w8213 Mounting Gp-Circuit Breaker
1130850 Mounting Gp-Circuit Breaker
7e1161 Mounting Gp-Circuit Breaker
4p7147 Mounting Gp-Circuit Breaker
1130849 Mounting Gp-Circuit Breaker
4w8215 Mounting Gp-Circuit Breaker
3n8873 Control Panel Mounting Gp
1044704 Mounting Gp-Control
10***04Mounting Group-Control Panel; -Emcp Ii1
See all parts with full part numbers in Heavy Parts AI →
4w8990 Current Transformer Mounting Gp
2w6621 Decalcomania & Accessories Plate Gp
0L***65Washer 20.5 mm(.812 In.)O. D.2
0S***20Bolt--Customer Grounding Bolt1
1A***06Bolt--Neutral Connection1
See all parts with full part numbers in Heavy Parts AI →
2w6622 Accessory Plates & Decalcomania Gp
0L***65Washer 20.5 mm(.812 In.)O. D.2
0S***88Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter3
0S***20Bolt--Customer Grounding Bolt1
See all parts with full part numbers in Heavy Parts AI →
4w5545 Plate Gp-Coupling
4w5270 Regulator Assembly
3n7755 Regulator Assembly
3n7751 Regulator Assembly
3N***51Regulator As; Circuit Breaker 125 Amperes1
See all parts with full part numbers in Heavy Parts AI →
3n7748 Regulator Assembly
4w5269 Regulator Assembly
4w5271 Regulator As
1145510 Regulator As
1167849 Regulator Gp-Voltage
11***49Regulator Group-Voltage; -Digital1
See all parts with full part numbers in Heavy Parts AI →
1081870 Regulator Gp
4w3893 Rotor Assembly
5n0658 Rotor Assembly
4w7468 Rotor As
1103405 Rotor As
1104933 Rotor As
4p3401 Rotor As
7w7523 Rotor Assembly
1w9061 Sender Gp-24 Volt
9y3847 Transformer As-Series Boost
9Y***47Transformer As; Bolt-Flange Head1
See all parts with full part numbers in Heavy Parts AI →
7c6979 Transformer As
4p9900 Transformer As
9y3856 Transformer As-Series Boost
Transformers-Current
7W***02Transformer0
7W***04Transformer-Current0
See all parts with full part numbers in Heavy Parts AI →
Lubrication System
1w2638 Oil Filter Gp
7c7775 Gauge Gp-Oil Level
7C***75Gauge Group-Oil Level (Dipstick)1
See all parts with full part numbers in Heavy Parts AI →
1w6479 Gauge Gp-Engine Oil Level
1W***79Gauge Group-Oil Level (Dipstick)1
See all parts with full part numbers in Heavy Parts AI →
7c6255 Lines Gp-Engine Oil-Front Sump
9n6334 Lines Gp-Engine Oil-Front Sump
4w1433 Lines Gp-Oil Drain
1w2206 Oil Pump Gp-Without Housing
1w2206 Pump Gp-Oil-Without Housing
Service Equipment And Supplies
Gasket Kits
6V***57Rear Structure-S/N 2z1-22070
6V***09Scroll & Sleeve Metering Fuel System0
6V***89Kit-Gasket; (Front Structure)(Front Structure)0
See all parts with full part numbers in Heavy Parts AI →
8f9866 Grease Gun Gp
Name Plates And Films-Part 1 Of 3
10***03(Italian)1
10***04(Swedish)1
10***05(Danish)1
See all parts with full part numbers in Heavy Parts AI →
Name Plates And Films-Part 2 Of 3
10***64Film; (Identification) (Engine Oil Filter)1
10***07Film-Warning; (Jump Start, Read Omm)1
10***08Film-Warning; (Jump Start, Read Omm)1
See all parts with full part numbers in Heavy Parts AI →
Name Plates And Films-Part 3 Of 3
10***04Film-Warning (Lifting) (Dutch)1
10***05Film-Warning (Lifting) (Greek)1
10***06Film-Warning (Lifting) (Italian)1
See all parts with full part numbers in Heavy Parts AI →
9s7977 Hand Tool Gp
Starting And Electrical System
7l7872 Battery Gp-24 Volt, 220 Ampere Hours
7c1899 Battery Gp
7c1976 Battery Gp
7l7871 Battery Gp-24 Volt, 172 Ampere (925 Cca)
7L***71Battery Group; (24-Volt)(24-Volt)1
See all parts with full part numbers in Heavy Parts AI →
7c1900 Battery Gp-24 Volt, 100 Ampere - Maintenance Free
7c1977 Battery Gp
7l7870 Battery Gp-24 Volt, 120 Ampere Hours
2w8903 Junction Box Gp-Part 2 Of 2
2w8907 Junction Box Gp
2W***07Junction Box Group1
7W***07Junction Box Group1
7W***51Switch Group; -Shutoff1
See all parts with full part numbers in Heavy Parts AI →
2w8685 Junction Box Gp-Power Distribution-Type 2
4w9602 Junction Box Gp-Part 1 Of 2
2w8905 Junction Box Gp
2w8901 Junction Box Gp
2W***01Junction Box Group1
7W***01Junction Box Group1
7W***51Switch Group; -Shutoff1
See all parts with full part numbers in Heavy Parts AI →
7w8001 Junction Box Gp
4W***01Junction Box Group1
7W***01Junction Box Group1
7W***52Diode Group1
See all parts with full part numbers in Heavy Parts AI →
4w9601 Junction Box Gp
7w8003 Junction Box Gp-Part 2 Of 2
2w8903 Junction Box Gp-Part 1 Of 2-Type 2
2w8903 Junction Box Gp-Part 1 Of 2
7w8003 Junction Box Gp-Part 1 Of 2
7w8007 Junction Box Gp-Part 2 Of 2
4w9602 Junction Box Gp-Part 2 Of 2
7w7999 Junction Box Gp
2w8907 Junction Box Gp-Part 1 Of 2
2w8907 Junction Box Gp-Part 2 Of 2
2w8685 Junction Box Gp-Power Distribution-Type 1
7w8007 Junction Box Gp-Part 1 Of 2
2w8903 Junction Box Gp-Part 2 Of 2-Type 2
4w9602 Junction Box Gp
2w8903 Junction Box Gp
2W***03Junction Box Group1
2W***35Wire As1
7W***03Junction Box Group1
See all parts with full part numbers in Heavy Parts AI →
6v4458 Starting Motor Gp-Electric
8c3651 Starting Motor Gp-Electric
8C***51Starting Motor Group-Electric; Starting Motor Gp-Electric-Delco-Remy1
See all parts with full part numbers in Heavy Parts AI →
4n9312 Starting Motor Gp-Electric
4n3181 Starting Motor Gp-Electric*R
3T***05Starting Motor Group-Electric; Starting Motor Group (Robert Bosch)1
4N***81Starting Motor Group-Electric1
8C***51Starting Motor Group-Electric; Starting Motor Gp-Electric-Delco-Remy1
See all parts with full part numbers in Heavy Parts AI →
9g4339 Starting Motor Gp-Electric
7t0799 Starting Motor Gp-Electric-24 Volt
6v5538 Motor Gp-Electric
9x4447 Starting Motor Gp-Electric
9X***47Starting Motor Group-Electric; Electric Starting Motor Group (Nippondenso)1
See all parts with full part numbers in Heavy Parts AI →
8c5580 Starting Motor Gp-Electric
7c9128 Starting Motor Gp-Electric-24 Volt
4M***61Bolt-To Assemble Valve As And Plates1
4N***59Gasket; (Starting Motor)1
7C***28Starting Motor Group-Electric1
See all parts with full part numbers in Heavy Parts AI →
6v5227 Starting Motor Gp-Electric*R
10***52Starting Motor Group-Electric1
6V***27Starting Motor Group-Electric1
6V***37Starting Motor Group-Electric1
See all parts with full part numbers in Heavy Parts AI →
3t6305 Starting Motor Gp-Electric
3T***05Starting Motor Group-Electric; Starting Motor Group (Robert Bosch)1
See all parts with full part numbers in Heavy Parts AI →
6v4451 Starting Motor Gp-Electric
6V***51Starting Motor Group-Electric1
6V***54Starting Motor Group-Electric1
6V***58Starting Motor Group-Electric1
See all parts with full part numbers in Heavy Parts AI →
6v4454 Starting Motor Gp-Electric
3n0519 Electric Starting Motor Gp-24 Volt
3N***19Starting Motor Group-Electric; Starting Motor Group1
See all parts with full part numbers in Heavy Parts AI →
1068552 Motor Gp-Electric
6v5537 Starting Motor Gp-Electric
2n6398 Alternator Assembly-24 Volt, 35 Ampere
6t1395 Alternator Gp-Charging*R
7n9720 Alternator Gp-Charging
7N***20Alternator Group; Alternator Group (Robert Bosch)1
See all parts with full part numbers in Heavy Parts AI →
6n9294 Alternator Gp-Charging*R
3T***52Alternator Group-Charging1
6N***94Alternator Group; (24-Volt, 35-Ampere)1
7N***20Alternator Group; Alternator Group (Robert Bosch)1
See all parts with full part numbers in Heavy Parts AI →
3t6352 Alternator Gp-Charging
4n9313 Alternator Gp-24 Volt, 35 Ampere-Low Mounted-Type 2
9g4574 Alternator Gp-Charging
9G***74Alternator Group-Charging; Alternator Group (Nippondenso)1
See all parts with full part numbers in Heavy Parts AI →
7t2095 Alternator Gp-Charging-24 Volt
4w8943 Alternator Gp-Charging
4p1998 Alternator Gp-Charging
4n9313 Alternator Gp-24 Volt, 35 Ampere-Type 1
7w3862 Charging Alternator Gp-24 Volt-35 Ampere
Battery Charger
7W***07Battery Charger; -12 Volt Dc For Use With Lead Acid Batteries Only0
7W***08Battery Charger; Battery Charger--24 Volt Dc0
7W***09Battery Charger; Battery Charger - 30 Volt Dc0
See all parts with full part numbers in Heavy Parts AI →
Battery Chargers
6L***27Battery Charger; Battery Chargers-120 Volt Input0
6L***11Battery Charger; Battery Charger--240 Volt Input0
6L***11Battery Charger; Battery Charger--208 Volt Input0
See all parts with full part numbers in Heavy Parts AI →
2w0972 Junction Box Gp-24 Volt
7w8005 Junction Box Gp
4W***02Junction Box Group1
5N***59Jumper-Strip1
7W***05Box Group-Junction1
See all parts with full part numbers in Heavy Parts AI →
9y7380 Junction Box Gp
5n8487 Automatic Start-Start Chart-Shut-Off & Alarm
5n9502 Connection Gp-Electrical
5n5576 Connection Gp-Electrical
7w0920 Connection Gp-Electrical
5n5576 Electrical Connection Gp-Type 1
5n9176 Contactor Gp-Oil Pressure & Water Temperature Shut-Off
5N***76Contactor Group; Contactor Gp-Oil Pressure &1
See all parts with full part numbers in Heavy Parts AI →
2w0971 Contactor Gp-Time Delay
2w0971 Time Delay Contactor Gp-12-24 Volt-Type 2
3n9602 Contactor Gp-Oil Pressure & Water Temperature
3N***02Contactor Group; Contactor Group Oil Pressure And Water Temperature1
See all parts with full part numbers in Heavy Parts AI →
4p5975 Contactor Gp-Water Temperature Shut-Off
2w9129 Contactor Gp-Alarm-Oil Pressure-Water Temperature
2w3046 Contactor Gp-Time Delay-24 Volt
7w5342 Contactor Gp-Alarm
5n9233 Contactor Gp-Overspeed-Type 3
5n9233 Contactor Gp-Overspeed-Type 1
5n9233 Contactor Gp-Overspeed-Type 2
5n8518 Oil Pressure & Water Temperature Contactor Gp
7e1234 Control Gp-Annunciator Electronic
9w3575 Control Gp-Electronic
9w3576 Control Gp-Electronic
1303349 Control Gp-Electronic
9w3574 Control Gp-Electronic-Annuciator*R
7c6513 Control Gp-Electronic-Type 1
5B***55Bushing-Reducer; (To Transmission Sump)1
7C***13Control Group-Emcp Electronic1
9W***65Sensor Group-Electronic; -Water1
See all parts with full part numbers in Heavy Parts AI →
9y6496 Control Gp-Electronic
9Y***96Control Group-Emcp Electronic; (Customer)1
See all parts with full part numbers in Heavy Parts AI →
1485368 Control Gp-Emcp Electronic
12***50Module Group-Relay Driver; Control Gp-Engine Monitoring1
14***68Control Group-Emcp Electronic1
6V***87Screw-Pan Head; (10-24x1-In)2
See all parts with full part numbers in Heavy Parts AI →
7c6513 Control Gp-Electronic
10***42Sensor Group-Pressure; Sensor As-Presssure1
3E***42Control Group-Engine Monitoring1
3S***93Strap-Cable-To Tie Harnesses Together2
See all parts with full part numbers in Heavy Parts AI →
9y2905 Control Gp
9Y***05Control Group-Emcp-Ecm Electronic1
See all parts with full part numbers in Heavy Parts AI →
6v6153 Control Gp-Electronic
6V***53Control Group-Emcp-Ecm Electronic1
See all parts with full part numbers in Heavy Parts AI →
9w5566 Control Gp-Electronic*R
9W***66Control Group-Engine Electronic1
See all parts with full part numbers in Heavy Parts AI →
9x8203 Control Gp-Electronic
9X***03Control Group-Engine Monitoring1
See all parts with full part numbers in Heavy Parts AI →
7w8052 Diode Gp
2w6262 Fastener Gp-Electrical Wiring Harness
00***72Clip (" " " )3
0L***43Bolt 63.5 mm (3/8" X 2 1/2" -Cover Assembly To Fender1
0S***09Bolt (3/4") Filler Tube Assembly To Transfer Drive Case2
See all parts with full part numbers in Heavy Parts AI →
5n0363 Fastener Gp-Overspeed Protection Conversion
2N***62Screw-Machine; (10-24x1.25-In)2
4B***74Washer (Required Only When Bosch Alternator Is Fitted)2
5N***63Fastener Group1
See all parts with full part numbers in Heavy Parts AI →
7w5084 Fastener Gp-Generator Set Wiring Harness
7c9284 Fastener Gp
2w1767 Harness As-24 Volt
1w6807 Harness As-Standby Package Generator Set
7c9102 Harness As-Wiring-Part 2 Of 2
7c9102 Harness As-Wiring-Part 1 Of 2
2w8919 Harness Gp-Wiring-Part 1 Of 2
2w8919 Harness Gp-Wiring-Part 2 Of 2
2w8925 Harness Gp-Wiring-Generator Interconnect
1430540 Starting Motor Gp-Electric-24 Volt*R
7c1766 Mounting Gp-Contactor
7w0034 Mounting Gp-Contractor
7c5023 Mounting Gp-Contactor
4w8994 Contactor Gp
9w5565 Sensor Gp-Electronic
9W***65Sensor Group-Electronic; -Water1
See all parts with full part numbers in Heavy Parts AI →
4w0888 Electric Shut-Off Gp-24 Volt-Type 1
5n9234 Shutoff Gp-Electric
4w0888 Electric Shut-Off Gp-24 Volt-Type 2
4w1688 Electrical Shut-Off Gp-12 Volt
4w1689 Electrical Shut-Off Gp-12 Volt
3t3421 Solenoid As
6t4750 Solenoid Shut-Off Gp-12 Volt
6T***50Solenoid As-Shutoff; Solenoid Shut-Off Group1
See all parts with full part numbers in Heavy Parts AI →
6n3749 Solenoid Shut-Off Gp-12 Volt
6N***49Solenoid As-Shutoff; Solenoid Shut-Off Group1
See all parts with full part numbers in Heavy Parts AI →
6t6122 Solenoid As-Shutoff
6T***22Solenoid As-Shutoff; Solenoid Gp-Shut-Off--Ledex Inc1
See all parts with full part numbers in Heavy Parts AI →
3t4704 Solenoid Assembly-24 Volt
7t8854 Solenoid Assembly-24 Volt
9n1068 Solenoid Shut-Off Gp-12 Volt
9N***68Solenoid Group-Shut-Off; Solenoid Shut-Off Group1
See all parts with full part numbers in Heavy Parts AI →
7n8884 Solenoid Shut-Off Gp-24 Volt
7N***84Solenoid Group-Shutoff; Solenoid Gp-Shut-Off1
See all parts with full part numbers in Heavy Parts AI →
6n9987 Solenoid Gp-Shut-Off
6N***87Solenoid Group-Shutoff1
6T***26Solenoid Group-Shutoff; Solenoid Gp-Shut-Off1
6T***22Solenoid As-Shutoff; Solenoid Gp-Shut-Off--Ledex Inc1
See all parts with full part numbers in Heavy Parts AI →
6n9988 Shut-Off Solenoid Gp-12 Volt
6N***49Solenoid As-Shutoff; Solenoid Shut-Off Group1
6N***88Solenoid Group-Shutoff1
6T***50Solenoid As-Shutoff; Solenoid Shut-Off Group1
See all parts with full part numbers in Heavy Parts AI →
6t4126 Solenoid Shut-Off Gp-24 Volt
6T***26Solenoid Group-Shutoff; Solenoid Gp-Shut-Off1
See all parts with full part numbers in Heavy Parts AI →
7c3268 Starting Aid Gp-Ether
4w6854 Ether Starting Aid Gp
7t0798 Starting Motor Gp-Electric
2s0900 Starting Motor As-24 Volt
6v5795 Starting Motor Gp-Electric
3t2652 Starting Motor Gp-Electric-*R-24 Volt, Type 3
3t2652 Starting Motor Gp-Electric-24 Volt*R-24 Volt, Type 2
8c3647 Starting Motor Gp-Electric
8C***47Starting Motor Group; Starting Motor Group-Electric1
See all parts with full part numbers in Heavy Parts AI →
3t2652 Starting Motor Gp-Electric-*R-Type 1
2w3932 Battery Support Gp
4m1812 Solenoid Switch Assembly
2w8916 Contactor As-Water Temperature Alarm
2W***16Switch As-Temperature; -Engine Coolant1
See all parts with full part numbers in Heavy Parts AI →
2w6831 Switch Gp-Oil Pressure Alarm
2W***31Switch Group; -Oil Pressure Alarm1
3J***07Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve1
6T***52Switch As-Pressure; (Engine Oil)1
See all parts with full part numbers in Heavy Parts AI →
2w8910 Switch Gp-Oil Step Protection
2W***10Switch Group; -Oil Step Protection1
3J***07Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve1
6T***51Switch As-Pressure; (Engine Oil)1
See all parts with full part numbers in Heavy Parts AI →
7w8051 Switch Gp
2w8911 Switch Gp-Starting Aid
2W***11Switch Group-Starting Aid; -Secondary Stop1
See all parts with full part numbers in Heavy Parts AI →
8l4849 Wiring Gp-Automatic Start-Stop
05***71Grommet-Junction Box1
1H***18Grommet--Junction Box1
1H***66Clip-Wire Provides Loose Parts6
See all parts with full part numbers in Heavy Parts AI →
7c9285 Wiring Gp
7C***02Harness As-Wiring1
7C***84Fastener Group-Wiring Harness1
7C***85Wiring Group1
See all parts with full part numbers in Heavy Parts AI →
4l1192 Wiring Gp
4L***92Wiring Group; Wiring Group Safety Shut-Off1
9G***71Sureseal Plug - 6 Pin1
9G***51Clip (10.2mm Id); (10.20mm Id)3
See all parts with full part numbers in Heavy Parts AI →

SR4 serial number reference

The identification plate for an SR4 generator end is mounted on the generator frame itself, near the terminal box, separate from any data plate on the driving engine. The serial number is a 3-character alpha prefix followed by a numeric sequence; the prefix identifies the production range, the digits are the individual unit number. On a genset package the engine carries its own separate prefix and plate, so match the prefix to the SR4 generator-end table, not the engine table, when ordering generator parts.

PrefixIdentifies
1WF, 2ED, 2WD, 3EF, 3WF, 4MD, 5CK, 5TD, 5UA, 5WA, 5XA, 6GA, 6GF, 6HA, 6JA, 6LA, 6MA, 6PK, 6SA, 7BF, 8FD, 8GK, 8HF, 9CFSR4 generator end (alternator), all frame sizes
5EASR4 generator, specific parts-catalog serial range
5NASR4 generator, specific parts-catalog serial range

Frequently asked questions

What engine powers the Caterpillar SR4?

None built in - the SR4 is a generator end only. Cat factory-paired it with different engines depending on frame size and kW rating, including the gas G3306 and diesel 3208, 3306, 3406/3406C, 3408, 3412, and 3512. Which engine shows up on a given SR4 depends entirely on that set's original frame and voltage/kW configuration.

What is the SR4's operating weight?

There's no single figure. The SR4 has no chassis or engine of its own, and its frame sizes span roughly the 400s up through the 800-class. Weight scales with frame size and lead configuration, so check the nameplate frame number or a frame-specific spec sheet rather than a generic weight.

What replaced the Caterpillar SR4?

Cat carried the same brushless, self-excited/PME architecture forward into the higher-output SR4B frames, then moved later generator-end designs to digital voltage regulation. No single successor model number is documented across every SR4 configuration - for a specific frame, confirm the current cross-reference with your Cat dealer.

What SR4 owners discuss

Does the SR4 come with its own engine, or is it just the generator end?
The SR4 is a generator end (alternator), not a complete engine-generator package on its own. Cat factory-matched it to whatever diesel the set required - owners report SR4 units riding behind 3208, 3306, 3406/3406C, 3408, and 3412 engines depending on frame size and kW rating. There is no single "SR4 engine." When you're chasing parts or a manual for one of these sets, match by frame number and serial prefix first, then confirm which engine is actually bolted to it - don't assume from the SR4 tag alone.
What's the deal with SR4 excitation and voltage regulation - any known quirks?
The SR4 is a brushless, revolving-field design with solid-state automatic voltage regulation. Two excitation schemes show up in the field: self-excited units draw both excitation power and voltage sensing off the main stator output, while PMPE (permanent magnet pilot exciter) units feed the regulator from an isolated source. Regulator hardware ranges from VR1 up through VR3, VR3F, and VR4, with the higher-numbered regulators adding multi-turn pots for voltage level and gain plus fuse/solid-state overcurrent protection. Owners running these sets note that engine speed directly drives output voltage - even a 5-10% governor or load-related rpm swing shows up as a matching 5-10% voltage swing at the terminals, so a "voltage problem" is often really a speed/governor problem upstream. If the AVR trips or shuts down under load, check for overload before assuming the regulator itself is bad. Have your dealer verify regulator settings and calibration before making adjustments.
How do owners check winding and insulation health on an SR4 generator end?
The standard field check is a megohmmeter (insulation resistance) test at 500-1000V across the stator, rotating field, exciter armature, and exciter field. A reading at or below one megohm generally means the winding has picked up too much moisture and needs drying out before it's put back in service. Test interval depends on environment: roughly every three months for units running exposed or in humid conditions, every six months for a clean enclosed installation, and weekly with supplemental space heaters for anything near salt air or humidity above about 75%, or after any reading under three megohms. Dirt and salt make moisture retention worse and accelerate insulation breakdown, so keep the generator housing clean and dry between tests.
What bearing and coupling issues come up on these generator ends?
Bearing location (inboard vs. outboard) and whether the unit runs a single or dual bearing arrangement depends on the pairing - engine size, generator frame size, and the vibration characteristics of both determine the layout, so don't assume one bearing configuration applies across every SR4-badged unit. Alignment between the generator rotor and the driving engine's crankshaft is the recurring theme in field reports: poor shimming, incorrect hold-down bolt torque, or skipping thermal-growth allowances during alignment leads to excess vibration, shortened bearing and coupling life, and repeat re-alignment jobs. Use a laser or dial-indicator alignment procedure and re-check after the set has run up to operating temperature, since thermal growth shifts the alignment from a cold setup.
What electrical/sensor problems show up most often on SR4 sets?
Exciter field diode failures are a recurring complaint - when these are replaced, polarity matters: positive-bus and negative-bus diodes are not interchangeable, and reversing one will re-blow the set almost immediately. Loose, corroded, or improperly crimped terminal connections are the other common thread behind intermittent voltage or no-output complaints - owners report chasing what looked like a regulator fault back to a bad harness connection or bent terminal at the exciter or main output leads. On the engine side (not the generator end itself), fuel shutoff solenoid failures are a frequent complaint on older 3306- and 3208-paired sets, usually traced to a bad coil or corroded connector rather than the solenoid body. Diode and wiring work on the exciter circuit is safety-critical - have your dealer verify polarity and connections before re-energizing the set.
Do power ratings and frame sizes vary a lot across SR4 units?
Yes, significantly - this is a family of generator ends built across multiple frame sizes (reports span roughly 446 through 687 frame) rather than one fixed rating. Field-reported outputs range from around 350 kW up to 800 kW and beyond (close to 1000 kVA on the largest 480V frames, and up to about 600 kW on 4160V units), at 1800 rpm, four-pole. Insulation class and power factor also vary by build (commonly Class F or H insulation, 0.8-0.9 power factor). Always confirm the specific frame and nameplate rating on the unit in front of you rather than assuming a number from a different SR4 you've worked on - specs don't carry across frame sizes.
What should I check before buying a used SR4 generator set?
First, identify the actual paired engine and confirm it matches the seller's description - SR4 gensets show up behind several different Cat diesels (3208, 3306, 3406/3406C, 3408, 3412), and parts/service data only line up correctly once you know which one you actually have. Verify the frame size and nameplate kW/kVA rating rather than assuming from the SR4 name alone, since output varies widely across the frame range. On the generator end itself: get a megohmmeter insulation resistance reading on the stator, rotor, and exciter windings before you buy, ask for the coupling/bearing alignment history, and inspect the exciter diode bridge and wiring harness for prior repair or corrosion damage. Ask for maintenance records covering both the engine and the generator end - a clean-running engine can still be paired with a generator end that's been sitting exposed and absorbing moisture. Have your dealer verify insulation resistance, bearing condition, and alignment before committing to a purchase.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

Serial-range & configuration variants

This page covers the Caterpillar SR4. Related factory variants of the same model family:

SR4SR4

Need a specific SR4 part?

Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.