Caterpillarwheel tractor-scraperwheel tractor
Caterpillar 651B
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 651B is a heavy-duty wheel tractor-scraper designed for bulk earthmoving, site development, and road construction. Part of the 600 series introduced in 1962, the 6 and 51 models were upgraded to the B series in 1968. This machine features a single-engine, two-axle configuration with a high-capacity powershift transmission. It is characterized by its massive dimensions, measuring over 50 feet long and 14 feet high, and is capable of producing approximately 410.1 kW (550 hp) of engine power.
The transition from the original 651 to the 651B marked a significant technological shift, replacing the previous 9-speed powershift transmission with a more advanced 8-speed version and increasing flywheel horsepower to 550 hp. This generation remained in continuous production from 1968 until 1984, when it was succeeded by the 651E. Today, the 651B remains a staple in the used market for large-scale excavation projects, though its maintenance requires strict adherence to fluid specifications and structural inspections to manage the high stresses of heavy hauling.
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 651B specifications
Engine
| Model | D346 |
| Net Power | 550 hp (410.1 kW) |
| Displacement | 1190 cu in |
| Power Measurement | 1900 rpm |
Weights
| Total Operating Weight (Empty) | 126,900 lb (57,558.5 kg) |
| Weight Range | Varies by configuration; approximately 124,000 lb to 126,900 lb |
Dimensions
| Overall Length | 50.33 ft (15.34 m) |
| Standard Operating Length | 51 ft 4 in (0.1 m) |
| Overall Width | 14.18 ft (4.32 m) |
| Overall Height | 14.08 ft (4.30 m) |
| Wheelbase | 31.92 ft (9.73 m) |
Performance
| Max Forward Speed | 32 mph (51.5 km/h) |
| Top Speed | 34 mph (54.7 km/h) |
| Transmission Type | 8-speed powershift (replaces previous 9-speed) |
| Bowl Heaped Capacity | 44 yd³ |
| Bowl Struck Capacity | 32 yd³ |
| Max Depth of Cut | 16 in (40.64 cm) |
| Width of Cut | 12 ft (3.66 m) |
Service capacities (summary)
| Fuel Capacity | 280 gal (1,060 L) |
| Hydraulic Fluid Type | Cat HYDO Advanced |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
651B fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| engine crankcase (with filter) | not documented | Cat DEO SAE 15W-40; use SAE 10W-30 for temperatures below 15°F (-9°C) |
| cooling system | not documented | fluid compatible with conventional and long life |
| hydraulic system and tank | not documented | Cat HYDO Advanced; use Bio HYDO Advanced where environmental safety rules are a priority |
| grease (spec only) | not documented | Cat Multipurpose Grease; Cat Advanced 3Moly Grease; Cat Ultra 5Moly Grease; Cat Desert Gold Grease (hot-weather); Cat Arctic Platinum Grease (cold-weather) |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 651B maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the 651B beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Caterpillar S.O.S Services to monitor engine oil, hydraulic fluid, coolant, and transmission oil. Analyze wear metals like iron or copper and contaminants such as silicon to detect early component degradation. For the 651B, regular hydraulic oil sampling is critical during PM3 intervals to prevent pump and valve failure. Use Cat HYDO Advanced oils to maximize drain intervals and protect hydraulic components from oxidation and particle contamination.
Corrective & Common Repairs
Frequent repairs on the 651B often involve addressing leaks in hydraulic hoses, pins, or bushings. Monitor for air filter restriction to prevent engine damage. If fuel-water separation fails, inspect the water separator and fuel filters immediately. Ensure all structural welds are inspected during major service intervals to identify cracks caused by heavy loading. Always verify that any replacement parts match the specific serial number prefix of your tractor.
Overhaul & Rebuild Points
Major component evaluation should occur during PM4 (2,000-hour) intervals. Key rebuild focus areas include the 8-speed power-shift transmission and the engine's turbocharger. Inspect the final drive and transmission oil for metal particles to signal an impending need for gear or bushing replacement. For machines with a cushion hitch (serial prefix 44M), ensure structural integrity is checked during comprehensive inspections to manage the increased operating weight.
Seasonal & Environment Servicing
In dusty or quarry environments, shorten air filter inspection intervals to daily and replace them every 500 hours. Clean radiator and oil cooler fins daily to prevent overheating. For cold-weather operations, use SAE 10W/30 engine oil to ensure reliable starting at temperatures near 15°F. In high-load applications, monitor the cooling system closely and perform coolant tests or flushes as scheduled to prevent internal liner pitting and corrosion.
651B common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 1D-4540 | Bolt,Machine Fuel Filter Mounting | Fuel system service | Check fitment → |
| 6I-2509 | Filter Element As-Air | Air intake service | Check fitment → |
| 6I-2510 | Filter Element As-Air | Air intake service | Check fitment → |
| 191-0965 | Shield-Oil Filter | Lubrication service | Check fitment → |
| 1R-0716 | Filter As-Engine Oil | Lubrication service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
651B fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| 110-0 | Engine Coolant Temperature — Above Normal | Low coolant level, thermostat failure | Inspect cooling system, refill coolant, test thermostat |
| 110-3 | Engine Coolant Temp Sensor — Voltage High | Open circuit or sensor failure | Check wiring; replace sensor if confirmed faulty |
| 174-3 | Engine Fuel Temperature — Voltage Above Normal | Open circuit in sensor wiring | Inspect harness and replace sensor if necessary |
| 190-8 | Engine Speed — Abnormal Frequency | Speed sensor air gap, sensor failure, or tone ring damage | Check sensor gap; test speed sensor and tone ring |
| 41-3 | 8-Volt DC Supply — Voltage Above Normal | Short to power on 8V reference circuit | Inspect sensors sharing the 8V supply and isolate fault |
| 41-4 | 8-Volt DC Supply — Voltage Below Normal | Short to ground on 8V reference circuit | Disconnect sensors one at a time to locate short |
| E360 | Engine Coolant Temperature — High | Low coolant, failed thermostat, or water pump issue | Diagnose cooling system; do not operate until resolved |
| E361 | Engine Coolant Temperature — Very High (Shutdown) | Severe cooling system failure | Engine shutdown required; perform full cooling system diagnosis |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
651B attachments & work tools
Specialty Power Unit Configurations
Tractor-only configurations are available for conversion into specialty machines. Typical applications include water pulls, elevating scrapers, and lowboy trailer power units.
Engine and Powertrain Options
The 651B features a 410.1 kW (550 hp) engine output at the flywheel. The machine utilizes an 8-speed powershift transmission, which replaced the previous 9-speed configuration.
Hitch and Attachment Systems
A factory-only cushion hitch option is available under serial number prefix 44M. This modification results in a weight increase to over 57 tons.
Hydraulic and Fluid Requirements
Hydraulic systems should use Cat HYDO Advanced oils for optimized drain intervals. For specific hydrostatic transmission requirements, use SAE 10W oil meeting Caterpillar TO-4 specification.
All 651B assemblies by section
Every catalogued assembly group for the Caterpillar 651B. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Air Inlet And Exhaust System
267-2822 Air Cleaner Gp
| 26***22 | Air Cleaner Group | 1 |
| 6I***09 | Filter Element As-Air; -Primary | 1 |
| 6I***10 | Filter Element As-Air; -Secondary | 1 |
254-3226 Connection Gp-Exhaust
| 16***36 | Coupling-Exhaust | 1 |
| 25***26 | Connection Group-Exhaust | 1 |
| 25***27 | Support-Exhaust | 1 |
299-9580 Conversion Gp-Air Inlet & Exh
| 26***22 | Air Cleaner Group | 1 |
| 27***55 | Tube As | 1 |
| 27***77 | Muffler Group | 1 |
1w-4751 Extension Gp-Exhaust
127-9039 Lines Gp-Air
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 4 |
| 10***25 | Gasket; (Air Inlet Manifold)(Intake Manifold Inlet) | 1 |
| 12***32 | Elbow | 1 |
114-1904 Lines Gp-Air
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 11***04 | Lines Group-Air | 1 |
| 5M***94 | Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler | 2 |
191-6147 Lines Gp-Air
| 13***03 | Support-Exhaust Pipe | 1 |
| 19***47 | Lines Group-Air | 1 |
| 2N***65 | Bolt-High Temperature; (3/8-16x1.75-In) | 2 |
299-9578 Lines Gp-Air
| 10***25 | Gasket; (Air Inlet Manifold)(Intake Manifold Inlet) | 2 |
| 10***03 | Elbow; (Air Inlet) | 1 |
| 16***96 | Tube | 2 |
299-9577 Lines Gp-Air
| 22***30 | Elbow | 1 |
| 24***06 | Hose; (Bellows) | 1 |
| 29***77 | Lines Group-Air | 1 |
135-6552 Manifold Gp-Exhaust
| 10***54 | Manifold-Exhaust; (Center) | 1 |
| 10***08 | Manifold-Exhaust; (End)(End) | 2 |
| 10***92 | Stud-Taperlock; (3/8-16x3.93in) | 11 |
253-7424 Mounting Gp-Air Cleaner
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 3 |
| 10***20 | Spacer; (10.5x25x20-mm Thk) | 2 |
| 1C***51 | Bolt--Installation Of 2v***26 Retainer | 2 |
149-5239 Mounting Gp-Muffler
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 2 |
| 0T***55 | Bolt; (3/8-16x4.25-In)(Location S) | 2 |
| 10***20 | Spacer; (10.5x25x20-mm Thk) | 5 |
283-9927 Mounting Gp-Muffler
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 3 |
| 10***20 | Spacer; (10.5x25x20-mm Thk) | 7 |
| 19***52 | Support As | 1 |
277-3877 Muffler Gp
| 19***80 | Washer-Hard; (17.5x32x8-mm Thk) | 4 |
| 1F***50 | Nut Rops Support | 3 |
| 1W***51 | Extension Group-Exhaust | 1 |
211-2254 Turbocharger Gp
| 11***87 | Bolt; (M6x0.04x10.4-mm)(6mm X 0.04 Thd) | 1 |
| 13***75 | Clamp As; (Service Repair) | 1 |
| 16***58 | Clip-Hose | 1 |
210-8818 Turbocharger Gp
| 1S***95 | Gasket-Turbocharger To Manifold; Gasket Turbocharger To Manifold | 1 |
| 21***18 | Turbocharger Group | 1 |
| 21***54 | Turbocharger Group | 1 |
194-7921 Turbocharger Gp
| 11***87 | Bolt; (M6x0.04x10.4-mm)(6mm X 0.04 Thd) | 1 |
| 16***58 | Clip-Hose | 1 |
| 16***60 | Hose; (Wastegate) | 1 |
192-3110 Turbocharger Gp
| 19***10 | Turbocharger Group | 1 |
| 19***21 | Turbocharger Group | 1 |
| 1S***95 | Gasket-Turbocharger To Manifold; Gasket Turbocharger To Manifold | 1 |
Basic Engine
133-9907 Adapter Gp-Pump Drive
| 13***06 | Adapter | 1 |
| 13***07 | Adapter Group-Pump Drive; -Remote | 1 |
| 1B***67 | Ball Bearing | 2 |
266-7781 Air Compressor Gp
| 03***43 | Adapter - 45 Degrees - 8 Valve Ports P, T, C1, C2 | 1 |
| 10***96 | Hose As | 1 |
| 10***05 | Hose As | 1 |
165-9175 Air Compressor Gp
| 03***49 | Elbow; (90 Degree, 37 Degree Flared) | 1 |
| 10***40 | Gear; (40-Teeth) | 1 |
| 11***04 | Seal | 1 |
166-8312 Air Compressor Gp
| 03***49 | Elbow; (90 Degree, 37 Degree Flared) | 1 |
| 10***40 | Gear; (40-Teeth) | 1 |
| 11***04 | Seal | 1 |
164-7566 Air Compressor Gp
| 0L***52 | Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex) | 6 |
| 0S***17 | Bolt --Use Open Hole In Compressor Body | 14 |
| 10***16 | Key-Woodruff | 1 |
238-2762 Air Compressor Gp
| 10***96 | Hose As | 1 |
| 10***05 | Hose As | 1 |
| 11***04 | Seal | 1 |
122-1248 Base Gp-Valve Cover & Inj Harn
| 06***91 | Terminal-Blade; (14-Ga To 18-Ga) | 6 |
| 10***01 | Kit; (Receptacle) (12-Pin) (Includes Receptacle As & Wedge) | 1 |
| 10***34 | Kit-Receptacle; (12-Pin)(Valve Cover & Inj Harness) | 1 |
194-6715 Belt Tensioner Gp
| 0L***51 | Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold | 2 |
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 3 |
| 0S***18 | Bolt; (5/16-18x1-In)(Hydraulic Pump) | 4 |
185-9699 Camshaft Gp
| 10***89 | Cover | 1 |
| 11***36 | Screw-Flat Head; (5/16-18x0.875-In) | 3 |
| 18***99 | Camshaft Group; (Single) | 1 |
140-9746 Cover Gp-Cylinder Block
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 4 |
| 12***35 | Seal-Integral | 1 |
| 14***46 | Cover Group-Cylinder Block; (Central Structure) | 1 |
107-6736 Cover Gp-Cylinder Block
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 10***36 | Cover Group-Cylinder Block; -Remote | 1 |
| 4N***99 | Gasket; (Oil Drain) | 1 |
7w-8531 Cover Gp-Flywheel Housing
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 0S***19 | Bolt,Machine Gear Retaining Part Of Kit P/N 1w***46 | 2 |
| 2P***72 | Cover Block R.H. Side | 2 |
159-6159 Cover Gp-Front Housing
| 03***55 | Locknut; (5/16-18-Thd)(Marked X) | 2 |
| 15***59 | Cover Group-Front Housing | 1 |
| 16***71 | Seal | 1 |
187-1328 Cover Gp-Valve Mechanism
| 15***35 | Cover Group-Valve Mechanism | 2 |
| 18***28 | Cover Group-Valve Mechanism | 1 |
| 34***04 | Cover Group-Valve Mechanism | 1 |
150-3135 Cover Gp-Valve Mechanism
| 14***78 | Grommet | 1 |
| 15***57 | Cover-Valve Mech | 1 |
| 15***35 | Cover Group-Valve Mechanism | 1 |
187-1326 Cover Gp-Valve Mechanism
| 14***78 | Grommet | 1 |
| 18***25 | Cover As-Valve | 1 |
| 18***26 | Cover Group-Valve Mechanism | 1 |
341-6804 Cover Gp-Valve Mechanism
| 14***78 | Grommet | 1 |
| 23***06 | Cover As-Valve | 1 |
| 24***37 | Seal; (Cover, Valve Mechanism) | 1 |
160-3913 Crankshaft Gp
| 15***32 | Crankshaft As | 1 |
| 16***13 | Crankshaft Group | 1 |
| 16***20 | Gear-Crankshaft; (80-Teeth) | 1 |
301-3016 Cylinder Block As
| 11***20 | Seal-O-Ring; (Mid-Liner) | 6 |
| 13***17 | Seal D-Ring | 6 |
| 13***81 | Liner-Cylinder Block | 6 |
267-4631 Cylinder Block As
| 16***81 | Cap-Crankshaft Bearing | 7 |
| 26***31 | Cylinder Block As | 1 |
| 3P***23 | Bolt-Bearing Cap; (7/8-14x7.75-In) | 14 |
234-9709 Cylinder Block As
| 11***20 | Seal-O-Ring; (Mid-Liner) | 6 |
| 13***17 | Seal D-Ring | 6 |
| 13***81 | Liner-Cylinder Block | 6 |
234-9702 Cylinder Block Gp
| 10***99 | Plug | 2 |
| 14***29 | Seal; (Drainback) | 1 |
| 1S***40 | Dowel; (30.23 mm X 9.37 mm) | 1 |
281-1640 Cylinder Head As
| 12***47 | Guide-Valve; (0.51-mm Os)(Standard) | 0 |
| 12***75 | Guide-Valve; (Standard) | 24 |
| 12***12 | Guide-Valve; (0.13-mm Os)(Standard) | 0 |
243-0943 Cylinder Head As
| 15***82 | Insert-Valve Seat; (Exhaust)(Standard) | 12 |
| 16***42 | Insert-Valve Seat; (0.76-mm Os Od, Exhaust)(Standard) | 0 |
| 16***43 | Insert-Valve Seat; (0.76-mm Os Od, Inlet) | 0 |
223-7263 Cylinder Head As
| 12***47 | Guide-Valve; (0.51-mm Os)(Standard) | 0 |
| 12***75 | Guide-Valve; (Standard) | 24 |
| 12***12 | Guide-Valve; (0.13-mm Os)(Standard) | 0 |
243-6741 Cylinder Head As
| 12***47 | Guide-Valve; (0.51-mm Os)(Standard) | 0 |
| 12***75 | Guide-Valve; (Standard) | 24 |
| 12***12 | Guide-Valve; (0.13-mm Os)(Standard) | 0 |
223-9250 Cylinder Head Gp
| 15***23 | Valve; (Inlet) | 12 |
| 15***24 | Valve; (Exhaust) | 12 |
| 16***78 | Seal-Valve Stem; (Exhaust) | 24 |
234-9185 Cylinder Head Gp
| 10***73 | Fastener Group-Cylinder Head; (Marked X) | 10 |
| 12***54 | Bolt-12 Point Head; (3/4-16x8.5-In) | 1 |
| 12***55 | Bolt-12 Point Head; (3/4-16x7.638-In) | 1 |
263-5055 Cylinder Head Gp
| 15***24 | Valve; (Exhaust) | 12 |
| 16***78 | Seal-Valve Stem; (Exhaust) | 24 |
| 18***01 | Rotocoil Assem. | 24 |
4p-5893 Damper Gp
| 16***26 | Damper Assem. | 1 |
| 16***00 | Spacer; (131.57mmx163.6mmx8mm Thk) | 1 |
| 1A***03 | Bolt 12.07 cm(4.75 In.) Long | 6 |
261-0669 Drive Gp-Fan
| 0S***66 | Bolt-Pulley To Crankshaft Adapter | 4 |
| 0S***90 | Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As) | 2 |
| 15***88 | Support-Compressor | 1 |
6i-3638 Drive Gp-Pump
| 0S***90 | Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As) | 3 |
| 13***07 | Adapter Group-Pump Drive; -Remote | 1 |
| 5M***94 | Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler | 4 |
258-4885 Fastener Gp-Flywheel Housing
| 16***29 | Bolt; (3/8-16x1.5-In)(Marked Z) | 2 |
| 25***85 | Fastener Group-Flywheel Housing | 1 |
108-9382 Fastener Gp-Front Housing
| 10***82 | Fastener Group-Front Housing | 1 |
| 14***68 | Stud-Taperlock | 2 |
| 1F***58 | Nut-Full; (1/2-13-Thd)(Air Lines) | 2 |
4p-6846 Fastener Gp-Front Housing
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 4P***46 | Fastener Group-Front Housing; -Remote | 1 |
| 5M***94 | Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler | 2 |
109-1657 Fastener Gp-Valve Mechanism
| 10***57 | Fastener Group-Valve Mechanism | 1 |
| 5J***94 | Screw,Cap,Socket He Manifold Mtg | 12 |
| 8L***13 | Strap-Cable(Tie 5.50" Long) | 6 |
8n-0953 Flywheel Gp
| 0S***01 | Bolt 2.75 In. (69.85 mm) Long | 12 |
| 4D***04 | Washer,Flat Cover Mtg,Accessory Drive | 12 |
| 7W***97 | Flywheel As | 1 |
204-9316 Gear Gp-Camshaft
| 10***26 | Dowel | 1 |
| 20***16 | Gear Group-Camshaft | 1 |
| 9X***72 | Bolt-Locking; (3/8-16x0.875-In) | 16 |
208-9490 Gear Gp-Front
| 03***85 | Bolt-12 Point Hd-Engine Flywheel To | 6 |
| 0S***71 | Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting | 1 |
| 10***68 | Bearing-Sleeve | 1 |
4n-9680 Governor Gp-Air Compressor
| 2K***98 | Seal-O-Ring | 1 |
| 2S***23 | Cover As; (Governor) | 1 |
| 4N***80 | Governor Group-Air Compressor | 1 |
218-2955 Housing Gp-Flywheel
| 12***02 | Housing-Flywheel | 1 |
| 14***68 | Seal-Crankshaft; (Rear)(Flywheel Housing) | 1 |
| 16***29 | Bolt; (3/8-16x1.5-In)(Marked Z) | 5 |
246-1048 Housing Gp-Front
| 06***55 | Seal-O-Ring (Id=47.22mm) | 1 |
| 0L***70 | Bolt (2-1/4") Filler Tube Assembly To Transfer Drive Case | 1 |
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 9 |
111-2088 Lifting Gp-Engine
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 8 |
| 10***85 | Eye-Lifting | 1 |
| 11***88 | Lifting Group-Engine; (Rear) | 1 |
111-2355 Lifting Gp-Engine
| 0S***95 | Bolt 1.25 In. (31.75 mm) Long Guard Assemblies To Radiator Guard | 4 |
| 11***44 | Eye-Lifting | 1 |
| 11***55 | Lifting Group-Engine; (Front) | 1 |
190-0009 Mechanism Gp-Fuel Pump & Valve
| 19***09 | Mechanism Group-Fuel Pump & Valve | 1 |
| 32***36 | Rocker Arm Group; -Non-Brake | 3 |
| 34***43 | Bridge-Valve | 12 |
148-7482 Mechanism Gp-Fuel Pump & Valve
| 14***82 | Mechanism Group-Fuel Pump & Valve | 1 |
| 19***98 | Rocker Arm Group | 3 |
| 6I***58 | Bridge-Valve | 12 |
162-7456 Pan Gp-Oil -Engine
| 0L***51 | Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold | 5 |
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 2 |
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 4 |
229-9933 Panel Gp-Sound Suppression -Front Housing
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 5 |
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 0T***55 | Bolt; (3/8-16x4.25-In)(Location S) | 1 |
134-3071 Piston & Rod Gp
| 13***71 | Piston & Rod Group | 1 |
| 13***05 | Ring-Piston; (Oil Control) | 1 |
| 14***30 | Ring-Piston; (Intermediate) | 1 |
353-9982 Plate As-Front Housing
| 12***57 | Washer; (10.85x19.3x1.27-mm Thk) | 9 |
| 12***27 | Washer-Special; (Sealing)(Sealing) | 2 |
| 12***28 | Stud; (Brake) | 12 |
305-9196 Plug Gp-Cylinder Block
| 30***96 | Plug Group-Cylinder Block | 1 |
| 6V***65 | O-Ring - For Oil Fill Plug | 1 |
| 9S***10 | Plug; (Straight Thread O-Ring)(Cylinder Head) | 1 |
235-2640 Plug Gp-Cylinder Block
| 03***53 | Seal-O-Ring; (08.92mm Id) | 1 |
| 13***27 | Seal-O-Ring; (19.18mm Id Base Side) | 1 |
| 18***09 | Plug As; (High Temperature) | 1 |
229-6711 Plug Gp-Cylinder Head
| 18***07 | Plug As; (Hi Tempertature) | 4 |
| 21***68 | Seal-O-Ring; (11.89-mm Id) | 1 |
| 22***11 | Plug Group-Cylinder Head | 1 |
234-5986 Plug Gp-Cylinder Head
| 18***07 | Plug As; (Hi Tempertature) | 4 |
| 21***68 | Seal-O-Ring; (11.89-mm Id) | 1 |
| 23***86 | Plug Group-Cylinder Head | 1 |
235-6266 Plug Gp-Cylinder Head
| 23***66 | Plug Group-Cylinder Head | 1 |
| 6V***09 | Seal-O-Ring (Id=16.36mm); (16.36-mm Id) | 2 |
| 9S***05 | Plug-O-Ring; (Straight Thread O-Ring) | 2 |
234-9184 Plug Gp-Cylinder Head
| 18***07 | Plug As; (Hi Tempertature) | 4 |
| 21***68 | Seal-O-Ring; (11.89-mm Id) | 1 |
| 23***84 | Plug Group-Cylinder Head; -Remote | 1 |
6n-8344 Pulley Gp-Auxiliary Drive
| 4N***34 | Pulley-Crankshaft; (4-Groove) | 1 |
| 6N***44 | Pulley Group-Auxiliary Drive; Auxiliary Drive Pulley Group | 1 |
| 8T***93 | Bolt (5/8-11 X 1.50 In); Bolt (5/8 X 11 X 1.5in) | 4 |
198-9898 Rocker Arm Gp
| 03***13 | Seal-O-Ring | 2 |
| 06***39 | Seal-O-Ring | 2 |
| 19***51 | Button; (24-mm Od) | 2 |
278-1929 Rocker Arm Gp
| 06***39 | Seal-O-Ring | 2 |
| 19***51 | Button; (24-mm Od) | 2 |
| 19***69 | Screw-Arm Adjustment; (9/16-18x2-In) | 2 |
328-4236 Rocker Arm Gp -Non-Brake
| 30***22 | Shaft As-Rocker Arm, Exhaust Manifold | 1 |
| 32***96 | Rocker Arm Group; -Intake | 4 |
| 32***36 | Rocker Arm Group; -Non-Brake | 1 |
328-4238 Rocker Arm Gp
| 06***39 | Seal-O-Ring | 1 |
| 19***51 | Button; (24-mm Od) | 1 |
| 19***69 | Screw-Arm Adjustment; (9/16-18x2-In) | 1 |
320-2796 Rocker Arm Gp
| 25***21 | Button | 1 |
| 27***91 | Screw-Arm Adjustment; (3/8-24x1.20-In) | 1 |
| 27***17 | Nut; (3/8-24-Thd) | 1 |
319-7401 Seal Gp-Crankshaft -Front
| 14***67 | Seal Group-Crankshaft; (Front) | 1 |
| 31***01 | Seal Group-Crankshaft; -Front | 1 |
185-6278 Support Gp-Engine -Front
| 18***78 | Support Group-Engine; -Front | 1 |
| 22***72 | Support-Engine | 1 |
| 5P***45 | Washer-Hard; (13.5x25.5x3-mm Thk)(Turbocharger Blanking Plate) | 8 |
277-3878 Support Gp-Engine
| 15***25 | Washer; (20.5x130x10-mm Thk) | 1 |
| 1D***14 | Bolt--Front Support To Frame | 2 |
| 1D***42 | Bolt 5 In. (12.7 cm) Long | 2 |
6n-6655 V-Belt Set
| 6N***55 | V-Belt Set; -Fan Drive | 1 |
Cooling System
299-9579 Cooling Ar
| 23***29 | Hose-Radiator | 1 |
| 29***78 | Lines Group-Air | 1 |
| 29***79 | Cooling Ar | 1 |
269-7243 Cooling Ar
| 01***24 | Bushing To Supply Port | 1 |
| 0L***51 | Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold | 2 |
| 0L***52 | Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex) | 1 |
109-2373 Fastener Gp-Water Pump
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 1 |
| 10***73 | Fastener Group-Water Pump; (Water Pump Cover) | 1 |
224-0875 Fitting Gp-Water Lines
| 22***75 | Fitting Group-Water Lines | 1 |
| 23***80 | Seal-O-Ring | 1 |
| 30***15 | Adapter As | 1 |
301-2986 Lines Gp-Water
| 14***67 | Clamp; (Hose) | 12 |
| 18***43 | Tube | 1 |
| 1T***20 | Bolt-12 Point Head; (3/8-16x1.25-In) | 8 |
238-6913 Lines Gp-Water
| 01***24 | Bushing To Supply Port | 1 |
| 0L***51 | Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold | 2 |
| 0L***52 | Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex) | 1 |
174-5986 Pump Gp-Water
| 10***77 | Seal-O-Ring; (100.97mm Id) | 1 |
| 12***72 | Seal-O-Ring (215.49mm Id) | 1 |
| 16***19 | Pump Group-Water | 1 |
161-5719 Pump Gp-Water
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 1 |
| 10***30 | Bearing As-Roller | 1 |
| 12***17 | Seal Group; (Water Pump) | 1 |
Electrical And Starting System
157-1774 Alternator Gp-Charging
| 15***58 | Bracket | 1 |
| 15***74 | Alternator Group-Charging | 1 |
| 16***65 | Strap | 1 |
200-8281 Alternator Gp-Charging
| 10***31 | Fan-Alternator; (11-Blade) | 1 |
| 18***34 | Nut-Flange; (5/8-18-Thd) | 1 |
| 1H***44 | Lockwasher (Bracket To Cab) | 2 |
126-7631 Connection Gp-Electrical
| 12***31 | Connection Group-Electrical; (Cylinder Block Ground) | 1 |
| 12***49 | Stud; (3/8-16, 5/8-18x3.1-In) | 1 |
| 5P***47 | Washer (Bracket To Valve Support) | 1 |
188-1758 Control & Mtg Gp-Engine Elek
| 0S***18 | Bolt; (5/16-18x1-In)(Hydraulic Pump) | 1 |
| 11***09 | Plate | 1 |
| 15***96 | Support As | 1 |
210-0849 Control Gp-Engine Electronic
| 21***49 | Control Group-Engine Electronic | 1 |
| 32***03 | Control Group-Engine Electronic | 1 |
322-3603 Control Gp-Engine Electronic
| 18***72 | Screw-Pan Head; (No 8-32x9.52-mm)(Wax Coated) | 1 |
| 32***03 | Control Group-Engine Electronic | 1 |
| 7X***15 | Strap; (Grounding) | 1 |
240-5304 Control Gp-Engine Electronic
| 18***72 | Screw-Pan Head; (No 8-32x9.52-mm)(Wax Coated) | 1 |
| 24***04 | Control Group-Engine Electronic | 1 |
| 7X***15 | Strap; (Grounding) | 1 |
9w-1494 Kit-Service Meter
| 11***05 | Film-Identification; (Service Meter) | 1 |
| 19***32 | Meter Group-Service | 1 |
| 20***19 | Wire As | 1 |
200-2301 Mounting Gp-Pressure Sensor
| 16***93 | Adapter | 1 |
| 1T***20 | Bolt-12 Point Head; (3/8-16x1.25-In) | 2 |
| 20***01 | Mounting Group-Pressure Sensor | 1 |
283-9803 Mounting Gp-Sensor
| 16***93 | Adapter | 1 |
| 28***03 | Mounting Group-Sensor | 1 |
| 3B***15 | Bolt Guard Assembly To Accessory Drive Housing | 2 |
236-2259 Sensor Gp-Engine
| 0S***91 | Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82 | 1 |
| 13***00 | Clip; (Tab) | 1 |
| 13***11 | Sensor Group-Temperature; (Transmission Lubrication Oil) | 3 |
204-7949 Sensor Gp-Position
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 18***35 | Pin-Connector; (16-Ga To 18-Ga) | 3 |
| 20***49 | Sensor Group-Position; -Throttle | 1 |
194-6725 Sensor Gp-Pressure
| 15***60 | Kit-Connecting Plug; (3-Pin)(Engine Sensor Wiring Harness) | 1 |
| 18***40 | Socket-Connector; (14-Ga To 18-Ga)(14-Ga To 18-Ga) | 3 |
| 19***25 | Sensor Group-Pressure; -Engine Oil | 1 |
194-6724 Sensor Gp-Pressure
| 15***60 | Kit-Connecting Plug; (3-Pin)(Engine Sensor Wiring Harness) | 1 |
| 19***26 | Harness As-Sensor; (16-18 Ga Wire)(Engine Oil Temperature) | 3 |
| 19***24 | Sensor Group-Pressure; -Air Inlet Manifold | 1 |
194-6722 Sensor Gp-Pressure
| 15***60 | Kit-Connecting Plug; (3-Pin)(Engine Sensor Wiring Harness) | 1 |
| 18***40 | Socket-Connector; (14-Ga To 18-Ga)(14-Ga To 18-Ga) | 3 |
| 19***22 | Sensor Group-Pressure; -Atmospheric Air | 1 |
201-6617 Sensor Gp-Speed
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 13***61 | Bracket | 1 |
| 15***70 | Kit-Connecting Plug; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
189-5746 Sensor Gp-Speed
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 14***36 | Pin-Connector; (14-Ga To 18-Ga) | 2 |
| 17***49 | Strap; (Marker) | 1 |
201-6615 Sensor Gp-Speed
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 12***67 | Pin-Connector; (14-Ga To 16-Ga)(14-Ga Wire) | 2 |
| 15***70 | Kit-Connecting Plug; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
130-9811 Sensor Gp-Temperature -Engine Oil
| 13***11 | Sensor Group-Temperature; (Transmission Lubrication Oil) | 1 |
| 13***45 | Pad; (Connector) | 1 |
197-8391 Sensor Gp-Temperature
| 13***45 | Pad; (Connector) | 1 |
| 19***91 | Sensor Group-Temperature; -Air Inlet Manifold | 1 |
| 23***80 | Seal-O-Ring | 1 |
207-1556 Starting Motor Gp-Electric
| 0S***97 | Capscrew (1/4 - 28 Nf X 1 Gd8, Hex) | 5 |
| 20***56 | Starting Motor Group-Electric; (24-Volt) | 1 |
| 25***79 | Kit-Solenoid; (24-Volt)(Starting Motor) | 1 |
207-1548 Starting Motor Gp-Electric
| 03***23 | Bolt; (1/4-28x1-In) | 5 |
| 19***70 | Solenoid As-Starting Motor; (24-Volt)(Starting Motor) | 1 |
| 20***48 | Starting Motor Group-Electric | 1 |
7w-7765 Starting Motor Gp-Electric
| 20***48 | Starting Motor Group-Electric | 1 |
| 7W***65 | Starting Motor Group-Electric | 1 |
| 8S***32 | Bolt; (12 Point Head) (5/8-11x1.75in) | 3 |
134-6054 Switch Gp-Flow -Coolant
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 13***54 | Switch Group-Flow; -Coolant | 1 |
| 18***35 | Pin-Connector; (16-Ga To 18-Ga) | 2 |
241-8368 Switch Gp-Magnetic
| 15***70 | Kit-Connecting Plug; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 18***36 | Socket-Connector; (16-Ga To 18-Ga) | 2 |
| 24***68 | Switch Group-Magnetic; -Main Power Relay-Main Relay | 1 |
9g-7641 Switch Gp-Start -Engine, Key
| 6V***62 | Screw-Machine; (8-32x0.31-In) | 4 |
| 7T***99 | Nut-Mounting; (1-32-Thd) | 1 |
| 9B***33 | Lockwasher; (Int'L Tooth) | 4 |
299-9581 Wiring Gp-Engine
| 03***10 | Sender As-Pressure; (Oil Pressure) | 1 |
| 10***01 | Kit; (Receptacle) (12-Pin) (Includes Receptacle As & Wedge) | 1 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 2 |
243-1564 Wiring Gp-Engine -Electronic Control
| 0S***09 | Bolt (3/4") Filler Tube Assembly To Transfer Drive Case | 4 |
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 2 |
Engine Arrangement
237-2797 Engine Ar-Complete
| 10***36 | Cover Group-Cylinder Block; -Remote | 1 |
| 10***82 | Fastener Group-Front Housing | 1 |
| 10***57 | Fastener Group-Valve Mechanism | 1 |
248-0453 Engine Ar-Core
| 12***48 | Base Group-Valve Cover & Inj Harn | 1 |
| 12***10 | Injector Group-Fuel | 6 |
| 13***71 | Piston & Rod Group | 6 |
299-9576 Installation Gp-Engine
| 27***78 | Support Group-Engine | 1 |
| 29***76 | Installation Group-Engine | 1 |
| 30***28 | Lines Group-Fuel | 1 |
Fuel System
209-3164 Filter Gp-Fuel
| 03***42 | Seal-O-Ring; (11.89mm Id) | 2 |
| 1A***29 | Bolt (1-1/8") Tube Assembly To Transfer Drive Case | 2 |
| 1B***90 | Bolt; (5/16-18x1.375-In)(Rh Front Cover) | 1 |
128-8510 Injector Gp-Fuel
| 10***72 | Spacer; (9.8x15.85x37.6-mm Thk) | 1 |
| 12***10 | Injector Group-Fuel | 1 |
| 21***25 | Injector Group-Fuel | 1 |
301-7928 Lines Gp-Fuel
| 00***73 | Elbow, Each Including: | 1 |
| 03***47 | Elbow-Filtered Fuel From Based Assembly | 1 |
| 11***28 | Elbow; (90-Deg) | 1 |
199-6554 Lines Gp-Fuel
| 03***42 | Elbow Hose Assembly To | 2 |
| 03***47 | Elbow-Filtered Fuel From Based Assembly | 2 |
| 03***62 | Elbow, Swivel Nut 45 Degrees (-6) | 1 |
283-9932 Lines Gp-Fuel
| 03***42 | Elbow Hose Assembly To | 2 |
| 03***47 | Elbow-Filtered Fuel From Based Assembly | 2 |
| 03***62 | Elbow, Swivel Nut 45 Degrees (-6) | 1 |
150-4279 Pump & Mtg Gp-Fuel Transfer -Rear
| 0S***99 | Stud (1.4325" Long) | 2 |
| 10***69 | Seal-O-Ring; (Fuel Transfer Pump) | 2 |
| 13***16 | Cover | 1 |
238-0296 Valve Gp-Check -Fuel
| 03***33 | Seal-O-Ring; (12.42mm Id) | 1 |
| 23***96 | Valve Group-Check; -Fuel Filter | 1 |
| 6V***23 | Ring; (Backup) (13.16mm Id) | 1 |
233-6742 Valve Gp-Check -Fuel
| 23***42 | Valve Group-Check; -Fuel Filter | 1 |
| 23***81 | Seal-O-Ring | 1 |
| 28***25 | Valve Group-Check; -Fuel | 1 |
281-2725 Valve Gp-Check -Fuel
| 03***33 | Seal-O-Ring; (12.42mm Id) | 1 |
| 28***25 | Valve Group-Check; -Fuel | 1 |
| 6V***23 | Ring; (Backup) (13.16mm Id) | 1 |
Lubrication System
283-9853 Fastener Gp-Fumes Disposal
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 1 |
| 28***53 | Fastener Group-Fumes Disposal | 1 |
| 8T***96 | Washer-Hard- Line From Pipe As. To Gear | 1 |
4n-2481 Fastener Gp-Oil Pump Mounting -Engine
| 0L***43 | Bolt 63.5 mm (3/8" X 2 1/2" -Cover Assembly To Fender | 2 |
| 0S***90 | Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As) | 1 |
| 4N***81 | Fastener Group-Oil Pump Mounting; Oil Pump Mounting Fastener Group | 1 |
167-7696 Filler Gp-Engine Oil
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 2 |
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 1 |
| 16***95 | Tube As-Oil Filler | 1 |
191-0966 Filter Gp-Engine Oil
| 0S***71 | Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting | 2 |
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 6 |
| 0S***90 | Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As) | 2 |
159-9362 Fumes Disposal Gp
| 15***62 | Fumes Disposal Group | 1 |
| 16***22 | Clip-Loop | 1 |
| 20***28 | Hose As; (Fumes Disposal) | 1 |
199-6348 Gauge Gp-Oil Level (Dipstick) -Engine
| 0L***70 | Bolt (2-1/4") Filler Tube Assembly To Transfer Drive Case | 1 |
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 1 |
| 11***68 | Seal-O-Ring; (15.54mm Id) | 1 |
261-0672 Lines Gp-Engine Oil
| 0S***71 | Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting | 1 |
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 2 |
| 0S***90 | Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As) | 1 |
138-2770 Lines Gp-Turbocharger Oil
| 0L***70 | Bolt (2-1/4") Filler Tube Assembly To Transfer Drive Case | 2 |
| 0S***71 | Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting | 2 |
| 10***44 | Elbow | 1 |
161-4113 Pump Gp-Engine Oil
| 12***56 | Cover As-Pump | 1 |
| 16***13 | Pump Group-Engine Oil | 1 |
| 1M***44 | Bolt; (3/8-16x2-1/4 In) | 2 |
Machine Arrangement
294-9578 Machine Ar
| 23***97 | Engine Ar-Complete | 1 |
| 29***78 | Machine Ar | 1 |
| 29***76 | Installation Group-Engine | 1 |
Operator Station
113-4799 Pedal Gp-Governor
| 11***99 | Pedal Group-Governor | 1 |
| 12***31 | Cover | 1 |
| 14***61 | Kit-Roller; (Foot Brake Control)(Governor Pedal) | 1 |
Power Train
299-9582 Cooler Gp-Transmission Oil
| 27***88 | Lines Group-Power Train Oil | 1 |
| 29***82 | Cooler Group-Transmission Oil | 1 |
| 30***32 | Gear Group-Transfer | 1 |
300-0432 Gear Gp-Transfer
| 03***20 | Bolt; (1/2-13x1.45-In) | 8 |
| 15***14 | Case-Transfer | 1 |
| 1A***29 | Bolt (1-1/8") Tube Assembly To Transfer Drive Case | 19 |
277-4688 Lines Gp-Power Train Oil
| 27***88 | Lines Group-Power Train Oil | 1 |
| 4J***20 | Seal (For Tilt Ports On Valve) | 1 |
| 4J***22 | Seal-Interface Between 3rd & Tilt Valve | 1 |
651B serial number reference
The PIN plate is typically located on the machine outer frame. The prefix consists of the first three alphanumeric characters of the serial number and identifies the specific model and manufacturing factory.
| Prefix | Identifies | Notes |
|---|---|---|
| 44M | Cushion Hitch Configuration | Identifies 651 units equipped with the factory-only cushion hitch ride control system. This modification increased machine weight to just over 57 tons (approx. 25,850 kg). All other specifications remained identical to non-cushion hitch models. |
Frequently asked questions
What is the engine horsepower for the Caterpillar 651B?
The Caterpillar 651B produces approximately 410.1 kW (550 hp) of engine power at the flywheel.
What is the approximate operating weight of this machine?
While standard weights vary by configuration, certain 651 models equipped with a cushion hitch can reach a weight of over 57 tons.
Which model replaced the Caterpillar 651B?
The Caterpillar 651B was officially replaced by the all-new 651E in 1984.
What 651B owners discuss
What are the primary transmission and braking issues reported for the 651B?
Operators have reported instances where brakes fail to hold the machine, creating a sensation that the transmission is continuously pushing the unit forward.
How does the transmission configuration differ between the original 651 and the 651B upgrade?
The 651B upgrade, introduced in 1968, replaced the previous 9-speed powershift transmission with a new 8-speed powershift system.
What is the engine power output for the Caterpillar 651B?
The machine produces 410.1 kW (550 hp) of engine power at the flywheel.
What specific hydraulic oil should be used to maintain the 651B system?
For Caterpillar hydraulic systems, use Cat HYDO Advanced oils or any SAE 10W oil meeting the Caterpillar TO-4 specification.
Are there known serial number variations for 651B machines with different hitch types?
Machines equipped with a cushion hitch were assigned a unique serial number prefix, 44M, to distinguish them from non-cushion hitch configurations.
What should be checked when inspecting a used 651B for potential heavy repairs?
Inspect the heat exchangers and oil coolers; specifically check for condition of the transmission oil cooler. Additionally, verify the engine power output and ensure it meets the 410.1 kW (550 hp) specification.
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 651B. Related factory variants of the same model family:
651B
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