Caterpillarengine - machine(no series)
Caterpillar 3306
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 3306 is a heavy-duty industrial, marine, and generator-set diesel: a mechanically governed inline six-cylinder engine displacing 10.5 liters (638 cu in), built on a 121 mm bore and 152 mm stroke. Caterpillar offered it in naturally aspirated, turbocharged, and turbocharged-aftercooled forms, with output spanning roughly 93-260 kW (125-350 hp) depending on aspiration, governed speed, and duty rating. Dry weight runs approximately 1,020-1,400 kg (2,250-3,090 lb), varying with accessories such as an aftercooler, marine gear, or heat-exchanger cooling package. Caterpillar introduced the 3306 in the early-to-mid 1970s as the successor to its earlier 1673 and 3160-series engines and kept it in production into the late 1990s and beyond for stationary and marine roles, well after electronically controlled engines took over most on-highway truck work.
Across its run the 3306 moved from an early mechanical fuel system to a revised fuel-pump and cylinder-head design, with running changes rather than a clean-sheet redesign — ratings, weight, and accessory-drive details shift by series and application, so treat horsepower and weight figures as configuration-specific, not fixed. Caterpillar eventually phased the family out of its industrial and generator-set catalogs in favor of electronically controlled engines as emissions rules tightened. The 3306 still matters in the used and parts market because of its size: decades of installed base in generator sets, pumps, compressors, and small marine vessels, a fully mechanical fuel and governor system with nothing electronic to fail, and a design built around routine in-frame overhauls that let well-maintained units keep running for tens of thousands of hours.
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 3306 specifications
Engine
| Configuration | In-line 6-cylinder, 4-stroke-cycle diesel, direct injection, counterclockwise rotation viewed from the flywheel end |
| Displacement | 10.5 L (638 cu in) |
| Bore x Stroke | 121 mm x 152 mm (4.75 in x 6.00 in) |
| Aspiration versions | Built as naturally aspirated (NA), turbocharged (T), and turbocharged-aftercooled (TA, including DITA/DINA/DIT cooling arrangements) |
| Power range, naturally aspirated | 93-127 kW (125-170 bhp) at 2000-2200 rpm rated speed |
| Power range, turbocharged | 142-205 kW (190-275 bhp) at 2000-2200 rpm rated speed |
| Power range, turbocharged-aftercooled | 194-250 kW (260-335 bhp) at 2000-2200 rpm rated speed |
| Duty/rating levels | Factory literature publishes five duty ratings per aspiration type, from A (continuous, 100% duty cycle) through E (short-term emergency/standby, 15-minute limit), each stepping the power ceiling up at the same displacement |
| Emissions | Predates EPA Nonroad emission-tier regulation; built as a mechanically governed, unregulated-era diesel with an inline mechanical fuel-injection pump. Factory emissions-upgrade kits were later offered for some arrangements, reducing particulate matter, NOx, hydrocarbons, and CO versus original build. |
Weights
| Net dry weight, naturally aspirated | 930 kg (2050 lb), approx |
| Net dry weight, turbocharged | 980 kg (2160 lb), approx |
| Net dry weight, turbocharged-aftercooled | 1007 kg (2220 lb), approx |
| Shipping/installed weight | Not separately published for the bare engine. Factory figures are net dry weight only; add oil, coolant, and any mounted accessories (alternator, radiator/fan, clutches, PTOs) for actual installed weight |
Dimensions
| Length | 1505 mm (59.2 in) |
| Width | 783 mm (30.8 in) |
| Height | 1171 mm (46.1 in) |
| Note | Figures are for the base long block per factory drawing. Optional radiator/cooling package, alternator, and power-takeoff equipment add to the installed envelope |
Performance
| Rated speed | 2000-2200 rpm, depending on rating level |
| Peak torque (approx, calculated from factory power/speed data) | roughly 1050 to 1350 Nm (780 to 1000 lb-ft) on turbocharged-aftercooled ratings, developed near 1500 rpm; lower and flatter on naturally aspirated builds. Varies by rating level and configuration |
| Full-load fuel consumption | 37-69 L/hr (9.9-18.2 US gal/hr) at rated speed, depending on rating level and aspiration |
| Torque rise | Factory literature describes the 3306 as a high-torque-rise design for flexible application range; exact torque-rise percentage not consistently published |
Service capacities (summary)
| Cooling system (engine only), DITA configuration | 18.2 L (4.8 US gal) |
| Cooling system (engine only), DINA/DIT configuration | 15.9 L (4.2 US gal) |
| Engine oil, refill with filter change | 27.4 L (7.3 US gal) |
| Fuel tank | Not applicable — the bare engine has no integral fuel tank. Tank is supplied by the host machine, generator set skid, or installation |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
3306 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with oil filter) | Varies by rating/configuration: approx. 27.4 L (7.3 US gal) for the turbocharged-aftercooled (TA/DITA) industrial rating; approx. 38.8 L (10.25 US gal) reported for the heavier vehicular/generator-set rating; a broader published range of 27-34 L (28.5-36 US qt) also appears across configurations. Varies by configuration/series - confirm against the engine arrangement number and OMM for the specific unit. | Cat DEO or Cat DEO-ULS multigrade diesel engine oil, API CF-4/CH-4 or higher (the older CF rating is now obsolete). Grade by expected ambient/start-up temperature per Cat's engine oil chart: SAE 0W-40 for -40C to 40C (-40F to 104F), SAE 10W-30 for -18C to 40C (0F to 104F), SAE 15W-40 for -9.5C to 50C (15F to 122F). Use the highest viscosity that still covers the coldest expected start. |
| Cooling system (engine jacket circuit) | 15.9 L (4.2 US gal) for naturally aspirated and turbocharged (DINA/DIT) builds; 18.2 L (4.8 US gal) for turbocharged-aftercooled (DITA) builds, engine-only. Full installed cooling circuits (radiator or heat exchanger, aftercooler loop, and hoses as fitted by the machine/genset builder) run materially higher, commonly cited from roughly 30 L up to about 68 L (32 US qt to 18 US gal) depending on the installation. Varies by configuration/series - use the host installation's own capacity figure where available. | Cat ELC (Extended Life Coolant), an extended-life ethylene-glycol antifreeze meeting ASTM D3306, D4985, D5345, D6210 and SAE J1034, no supplemental additive needed until the single Extender treatment at half coolant life. Cat DEAC (conventional alkaline ethylene-glycol coolant) is the alternate fill, but needs periodic dosing with a Supplemental Coolant Additive or SCA-charged coolant filters. |
| Fuel tank / fuel system | Not a fixed figure in the engine's own service chart. The 3306 ships as a bare industrial, generator-set, marine-auxiliary, or vehicular power unit, so tank size is set by whoever builds the machine, set, or vessel around it. Generator sub-base and skid tanks for 3306 sets are commonly seen in the roughly 1,100-3,800 L (300-1,000 US gal) range, but this is an installation choice, not an engine spec. | Diesel meeting the No. 1-D/No. 2-D specification under ASTM D975, run through the engine's mechanical direct-injection fuel system. Service fuel filters on the interval given in the maintenance schedule. |
| Transmission / hydraulic / final drive / axle compartments | Not applicable to the 3306 engine itself. | The 3306 is a bare engine with no transmission, hydraulic circuit, final drive, or axle of its own. Where it's installed as the power unit in a complete machine, those compartments and their Cat TDTO/HYDO/AXO fills belong to that host machine's own operation and maintenance manual, not the engine's. |
| Grease (all points, spec only) | Spec only - no system fill volume. Apply per fitting on the lubrication interval schedule. | Cat Multipurpose Grease, NLGI Grade 2, lithium-complex thickener, non-moly, for general accessory-drive and linkage grease points. Usable roughly -20C to 140C (-4F to 284F). |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 3306 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 6,000 h |
|
| Every 12,000 h |
|
Servicing the 3306 beyond the schedule
Predictive Maintenance & Fluid Analysis
Run scheduled oil sampling on the 3306's wet-sump system to catch bearing and liner wear before it reaches the mechanical injection pump or turbocharger bearings. Because the engine has no ECM to flag faults, watch crankcase blow-by and exhaust smoke color as your early-warning signs. Track coolant corrosion-inhibitor concentration closely — this long-stroke iron block is prone to cylinder-liner cavitation if inhibitor levels drop. Pull fuel filters early if sediment shows up, since the mechanical injection pump runs tight internal clearances.
Corrective & Common Repairs
Most 3306 complaints trace to the fuel injection pump and nozzles: hard starting, uneven idle, or white smoke usually mean pump wear or a sticking nozzle, not electronics. Water pump seal leaks and turbocharger oil seals are common wear points on high-hour units — watch for coolant weep holes and blue exhaust smoke. Valve lash drifts with age since there's no electronic timing to compensate, so recheck clearance whenever performance softens. Head gasket seepage around liner O-rings is a frequent oil-in-coolant culprit.
Overhaul & Rebuild Points
With no chassis or undercarriage of its own, 3306 rebuild work centers on the block: wet cylinder liners, pistons, and main/rod bearings are the core in-frame overhaul items, and liner protrusion and bore taper should be checked at every teardown. Recondition the cylinder head's valves, guides, and seats as a set rather than one at a time. Send the turbocharger out for bearing and seal rebuild alongside the injection pump and nozzles, and replace water pump and thermostat housings if pitted before closing up the cooling circuit.
Seasonal & Environment Servicing
Cold starts on a mechanically governed 3306 rely on intake-heating aids and correct coolant antifreeze concentration — check both before winter duty. In marine and coastal installs, inspect raw-water pump impellers and heat-exchanger tubes for salt buildup and galvanic corrosion each season. Dusty industrial or quarry sites call for shorter air-filter and oil-sample intervals than the standard chart. Standby gensets that sit idle need periodic exercise runs so fuel doesn't gum the injection pump and seals don't dry out.
3306 common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 1P-2299 | Filter As-Fuel | Fuel system service | Check fitment → |
| 2Y-8670 | Filter As-Fuel | Fuel system service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
3306 fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| Low Oil Pressure Shutdown | Engine oil pressure switch trips and energizes the fuel shutoff solenoid, moving the fuel rack to the stop position and killing the engine because pressure has fallen below the safe minimum. | Worn main or rod bearings, worn oil pump, plugged suction screen, low oil level, or a faulty pressure switch/sender. | Check oil level and condition first, then verify pressure at the block with a mechanical test gauge (normal is roughly 345-550 kPa / 50-80 psi at rated speed and 140-275 kPa / 20-40 psi at idle) before condemning the switch. |
| High Coolant Temperature Shutdown | A thermal sensing element in the water temperature regulator housing trips a microswitch when coolant overheats, energizing the same fuel shutoff solenoid and stopping the engine. | Low coolant level, plugged radiator core, slipping or failed fan drive, stuck thermostat, or water pump failure. | Check coolant level and look for external leaks, inspect the fan drive and radiator core, then confirm the sending unit/switch operation before replacing it. |
| Engine Overspeed Shutdown | A mechanical overspeed contactor switch mounted on the tachometer drive senses excess engine speed and energizes the fuel shutoff solenoid; it requires a manual reset push button before the engine can be restarted. | Governor linkage binding or misadjustment, a runaway condition from turbocharger oil ingestion, or a faulty overspeed switch. | Do not restart until the cause of the overspeed event is found. Check governor linkage and turbocharger seals, then reset the switch only after inspection. |
| Low Oil Pressure Warning (gauge) | Dash oil pressure gauge reads below the normal operating band, an early warning ahead of the automatic shutdown point. | Same root causes as the shutdown event caught earlier: worn oil pump, wrong oil viscosity, or a failing gauge sender. | Reduce load, verify gauge accuracy against a mechanical test gauge, and shut down for inspection before the automatic cutoff engages. |
| High Coolant Temperature Warning (gauge) | Dash water temperature gauge shows a rising reading above the normal operating range before the thermal switch trips a shutdown. | Cooling system airflow restriction, low coolant level, or a sticking thermostat. | Reduce load and let the engine idle to cool, inspect the cooling system, and avoid running repeatedly to the automatic shutdown point. |
| Genset control panel alarm/shutdown lamp (oil pressure, coolant temperature, overspeed, fail-to-start) | On generator-set packages built around this engine, a separate control/monitoring panel repeats these same fault conditions as lit alarm or shutdown lamps rather than as a numeric engine fault code, since the engine itself has no control module. | Same mechanical faults as above (oil pressure, coolant temperature, overspeed); the panel is only relaying the engine's switch inputs plus its own crank/start logic. | Diagnose from the engine side first (oil pressure, coolant, governor/overspeed switch) since the panel has no engine-level self-diagnostics to narrow the fault further. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
3306 attachments & work tools
Flywheel housing / SAE coupling interface
The 3306 uses a standard SAE No. 1 flywheel housing as its universal mounting face. Packagers bolt driven equipment straight to this housing - a generator end, a marine reverse/reduction gear, or a stationary pump/compressor drive - without engine-side modification.
Generator-set (genset) packages
Diesel 3306 gensets were built mainly in the 150-250 ekW standby class (naturally aspirated through turbocharged-aftercooled ratings); natural-gas G3306 sets ran lower, roughly 85-150 ekW continuous at 1800 rpm. Typical package: engine plus a matched generator end on a common skid base with an analog or digital control panel; open-skid, radiator-cooled arrangements were the standard industrial configuration.
Marine propulsion arrangement
For propulsion duty the 3306 (DIT/DITA ratings) couples through its flywheel housing to a separate marine reverse/reduction gear (e.g. Twin Disc). Reduction ratio depends on the gear model and the boat's propeller/hull requirement - commonly in the 2.5:1 to 3:1 range on recorded installations - so confirm the exact ratio with the gear builder for a given vessel rather than assuming one figure.
Marine/genset cooling arrangement
Marine-duty packages built on this engine family offered raw-water heat-exchanger cooling (engine-mounted heat exchanger with a gear-driven raw-water pump) or keel cooling as alternatives to a radiator, letting the engine run enclosed in an engine room. Radiator cooling remained the standard arrangement for land-based industrial and genset builds. Cooling-option specifics are best confirmed against the exact marine arrangement/rating plate, since published marine literature covering this detail sits mostly at the 3306 engine-family level rather than one universal spec.
Industrial stationary/pump-drive arrangement
As a bare industrial power unit the 3306 was commonly supplied as a stationary driver for irrigation, dewatering, or general belt/shaft-driven pump and compressor loads. There is no dedicated Cat quick-coupler for this class of engine - the driven pump, or an aftermarket front-mount PTO clutch, bolts directly to the SAE flywheel housing or front crankshaft pulley.
Front accessory drive
Belt- and gear-driven front-end accessories - cooling fan, alternator/charging generator, and (on marine and some industrial builds) a raw-water or auxiliary pump - are taken off the crankshaft pulley and accessory drive gear train. Which accessories are fitted varies by whether the engine is built up as an industrial, marine, or genset arrangement.
Guarding
Packaged genset and industrial arrangements carry a fan guard and a coupling/vibration-damper guard as standard equipment. Belt guards and shaft/coupling guards for driven equipment are added at the installation level to match the specific pump, generator, or marine-gear coupling and local safety code.
All 3306 assemblies by section
Every catalogued assembly group for the Caterpillar 3306. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Air Inlet And Exhaust System
7s6748 Air Cleaner Group
| 7S***48 | Air Cleaner Group | 1 |
7s6748 Air Cleaner Gp
| 7S***48 | Air Cleaner Group | 1 |
4n9586 Fastener Gp-Exhaust Manifold
| 4N***86 | Fastener Group-Exhaust Manifold; Exhaust Manifold Fastener Group | 1 |
2p6838 Air Lines Group
| 2P***38 | Lines Group-Air; Air Lines Group | 1 |
2p6572 Exhaust Manifold Group
| 2P***72 | Manifold Group-Exhaust; Exhaust Manifold Group | 1 |
1p1241 Muffler Group
| 1P***41 | Muffler Group | 1 |
2p7351 Exhaust Pipe Group
| 2P***51 | Pipe Group-Exhaust; Exhaust Pipe Group | 1 |
Basic Engine
1n4406 Camshaft Gp
| 1N***06 | Camshaft Group-Single; Camshaft Group--Single | 1 |
2y5174 Cylinder Block Cover Group
| 2Y***74 | Cover Group-Cylinder Block | 1 |
2p6530 Cover Gp-Cylinder Head
| 2P***30 | Cover Group-Cylinder Head; Cylinder Head Cover Group | 1 |
2y5248 Front Housing Cover Group
| 2Y***48 | Cover Group-Front Housing; Front Housing Cover Group | 1 |
2p6516 Cover Gp-Valve Mechanism
| 2P***16 | Cover Group-Valve Mechanism; Valve Mechanism Cover Group | 1 |
Crankshaft Bearing Replacements
| 8N***25 | Bearing (1.25mm Undersize) | 7 |
| 8N***26 | Bearing (0.51mm Undersize) | 7 |
| 8N***27 | Bearing (0.76mm Undersize) | 7 |
2y5206 Crankshaft Gp
| 2Y***06 | Crankshaft Group; Crankshaft Group | 1 |
2y5235 Cylinder Block As
| 2Y***35 | Cylinder Block As | 1 |
7n6550 Cylinder Block As
| 7N***50 | Cylinder Block As | 1 |
8n3021 Cylinder Block Gp
| 8N***21 | Cylinder Block Group; Cylinder Block Group | 1 |
1n3576 Cylinder Block Gp
| 1N***76 | Cylinder Block Group | 1 |
2y9363 Cylinder Block Gp
| 2Y***63 | Cylinder Block Group | 1 |
2y9518 Cylinder Head Gp
| 2Y***18 | Cylinder Head Group | 1 |
2p6476 Cylinder Head Gp*R
| 2P***76 | Cylinder Head Group; Cylinder Head Group | 1 |
8n1187 Cylinder Head Gp
| 8N***87 | Cylinder Head Group | 1 |
2p7838 Damper Group
| 2P***38 | Damper Group; Damper Group | 1 |
2p7831 Fan Drive Group
| 2P***31 | Drive Group-Fan; Fan Drive Group | 1 |
2y9484 Engine Ar-Part 1 Of 2
| 1N***06 | Camshaft Group-Single; Camshaft Group--Single | 1 |
| 1P***44 | Breather Group | 1 |
| 2P***29 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
2y9484 Engine Ar-Part 2 Of 2
| 2P***26 | Valve-Mechanism Group; Valve Mechanism Group | 1 |
| 2P***37 | Pump Group-Oil; Engine Oil Pump Group | 1 |
| 2P***72 | Manifold Group-Exhaust; Exhaust Manifold Group | 1 |
7n9536 Fastener Gp-Cylinder Head
| 7N***36 | Fastener Group-Cylinder Head; Cylindetr Head Fastener Group | 1 |
2p6546 Fastener Gp-Cylinder Head
| 2P***46 | Fastener Group-Cylinder Head; Cylinder Head Fastener Group | 1 |
5y0376 Fastener Gp-Cylinder Head
| 5Y***76 | Fastener Group-Cylinder Head | 1 |
2y5717 Front Housing Fastener Group
| 2Y***17 | Fastener Group-Front Housing; Front Housing Fastener Group | 1 |
5s3451 Flywheel Group
| 5S***51 | Flywheel Group; Flywheel Group | 1 |
2y5707 Front Timing Gear Group
| 2Y***07 | Gear Group-Front; Gear Gp-Front Timing | 1 |
2p6129 Flywheel Housing Group
| 2P***29 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
2y5250 Housing Gp-Front-Timing Gear
| 2Y***50 | Housing Group-Front; Front Housing Group | 1 |
2y8429 Housing Gp-Front
| 2Y***29 | Housing Group-Front | 1 |
6n8326 Lifting Eye Gp-Engine
| 6N***26 | Lifting Group; Lifting Eye Gp-Engine | 1 |
2y7719 Lifting Eye Gp-Engine
| 2Y***19 | Lifting Group-Engine; Lifting Eye Gp-Engine | 1 |
2s6981 Parts Gp-Miscellaneous
| 0S***09 | Bolt (3/4") Filler Tube Assembly To Transfer Drive Case | 1 |
| 1A***37 | Bolt Clutch Assembly To Bracket (Fan Support) | 4 |
| 1D***17 | Nut-Plate And Angle Assembly To Hydraulic And Fuel Tanks; Nut Plate And Angle Assembly To Hydraulic And Fuel Tanks | 1 |
4n4028 Rod & Piston Gp-6 Required
| 4N***28 | Piston & Rod Group; Connecting Rod And Piston Group | 1 |
2y2943 Pulley Group
| 2Y***43 | Pulley Group; Pulley Group | 1 |
6n0220 Crankshaft Seal Group
| 6N***20 | Seal Group-Crankshaft | 1 |
2p7751 Support Gp-Engine
| 2P***51 | Support Group-Engine; Engine Support Group | 1 |
7n9589 Trunnion Gp
| 7N***89 | Trunnion Group-Engine | 1 |
2p6526 Valve Mechanism Gp
| 2P***26 | Valve-Mechanism Group; Valve Mechanism Group | 1 |
Blade Controls, Hydraulic/Steering System
1g1305 Control Gp-Power-Front View-Part 1 Of 3
| 1G***05 | Control Group-Power | 1 |
1g1305 Control Gp-Power-Side View-Part 2 Of 3
| 1G***05 | Control Group-Power | 1 |
1g1305 Control Gp-Power-Side View-Part 2 Of 2
| 1G***05 | Control Group-Power | 1 |
1g1305 Control Gp-Power-Front View-Part 1 Of 2
| 1G***05 | Control Group-Power | 1 |
1g1305 Control Gp-Power-Side View-Part 3 Of 3
| 1G***05 | Control Group-Power | 1 |
2y8488 Cylinder Gp-Blade Side Shift
| 2Y***88 | Cylinder Group | 1 |
6g4415 Cylinder Gp-Blade Side Shift
| 6G***15 | Cylinder Group | 1 |
4j4115 Steering Cylinder Group
| 4J***15 | Cylinder Group-Steer | 1 |
2y4314 Power Control Drive Shaft Group
| 2Y***14 | Drive Shaft Group-Power Control | 1 |
2d2150 Filter Gp
| 2D***50 | Filter Group | 1 |
2y2160 Hydrostatic Gp-Steering-Part 1 Of 2
| 2Y***60 | Hydrostatic Group-Steering | 1 |
2y2160 Hydrostatic Gp-Steering-Part 2 Of 2
| 2Y***60 | Hydrostatic Group-Steering | 1 |
2y5394 Joint As
| 2Y***94 | Joint As | 1 |
2y7205 Joint As-Universal
| 2Y***05 | Joint As | 1 |
2y5396 Joint As
| 2Y***96 | Joint As | 1 |
2y7207 Joint As-Universal
| 2Y***07 | Joint As | 1 |
2d7836 Lift Gp-Blade-Part 1 Of 2
| 2D***36 | Lift Group-Blade | 1 |
2d7836 Lift Gp-Blade-Part 2 Of 2
| 2D***36 | Lift Group-Blade | 1 |
3g9801 Metering Pump Group
| 3G***01 | Pump Group-Metering | 1 |
2y3734 Pump Gp-Vane
| 2Y***34 | Pump Group-Vane | 1 |
4b8580 Shaft Gp-Control
| 4B***80 | Shaft Group-Control; Control Shaft Group | 1 |
2d4125 Shaft Gp-Leaning Wheel Control
| 2D***25 | Shaft Group-Leaning Wheel Control | 1 |
1g0642 Steering Gear Tank Group
| 1G***42 | Steering Gear Tank Group | 1 |
1g0643 Tank And Pump Group
| 1G***43 | Tank And Pump Group | 1 |
2y2250 Valve & Lines Gp
| 2Y***50 | Valve & Lines Group | 1 |
2y1947 Valve As
| 2Y***47 | Valve As | 1 |
2y3697 Valve Gp
| 2Y***97 | Valve Group | 1 |
2y2175 Valve Gp-Relief
| 2Y***75 | Valve Group-Relief | 1 |
Brakes
4b8759 Brake As-Cylinder
| 4B***59 | Brake As-Cylinder | 1 |
1g2298 Brake As-L.H.
| 1G***98 | Brake As-Lh | 1 |
1g2299 Brake As-R.H.
| 1G***99 | Brake As-Rh | 1 |
3d9200 Brake Gp-Hydraulic Rear Wheel
| 3D***00 | Brake Group-Hydraulic | 1 |
4d4170 Control Gp-Clutch & Brake-Side View
| 4D***70 | Control Group-Brake & Clutch | 1 |
4d4170 Control Gp-Clutch & Brake-Front View
| 4D***70 | Control Group-Brake & Clutch | 1 |
2y4902 Control Gp-Hydraulic Brake
| 2Y***02 | Control Group-Hydraulic Brake | 1 |
3d2219 Cylinder As
| 3D***19 | Cylinder As | 1 |
5t7161 Cylinder Gp-Wheel
| 5T***61 | Cylinder Group-Wheel | 1 |
2y1040 Tandem Drive Housing Group
| 2Y***40 | Housing Group-Tandum Drive | 1 |
2y5565 Lever As-Brake
| 2Y***65 | Lever As-Brake | 1 |
Cab, Gauges And Accessories
2y2000 Cab Door Gp
| 2Y***00 | Cab Door Group | 1 |
2y2020 Cab Gp
| 0T***42 | Bolt | 5 |
| 2D***34 | Glass (Untinted) | 1 |
| 2P***52 | Spring | 1 |
2y1270 Cab Gp
| 2Y***70 | Cab Group | 1 |
2y1982 Door Gp-Lh
| 2Y***82 | Door Group-Lh | 1 |
2y1981 Door Gp-Rh
| 2Y***81 | Door Group-Rh | 1 |
2y7633 Gauge Gp
| 2Y***33 | Gauge Group | 1 |
2y6835 Gauge Gp
| 2Y***35 | Gauge Group | 1 |
8d8175 Gauge Gp
| 8D***75 | Gauge Group | 1 |
8f9866 Grease Gun Gp
| 8F***66 | Grease Gun As | 1 |
2y7212 Hardware Gp-Cab
| 0T***24 | Bolt 9.525 mm(.375 In.) Dia. N. C. | 4 |
| 1B***03 | Nut Exhaust Pipe To Starting Engine Cylinder Block | 8 |
| 1D***17 | Nut-Plate And Angle Assembly To Hydraulic And Fuel Tanks; Nut Plate And Angle Assembly To Hydraulic And Fuel Tanks | 18 |
1g1553 Platform Gp-Seat Frame & Fuel Tank
| 1G***53 | Platform Group | 1 |
2y5468 Seat Belt Group
| 2Y***68 | Seat Belt Group | 1 |
2y2232 Seat Frame Assembly
| 2Y***32 | Seat Frame As | 1 |
6g2090 Seat Group
| 6G***90 | Seat Group | 1 |
2y2576 Tool Gp
| 2Y***76 | Tool Group-Hand | 1 |
2y1995 Windshield Gp
| 2Y***95 | Windshield Group | 1 |
Chassis
2d4140 Axle Gp-Front-Part 2 Of 3
| 2D***40 | Axle Group-Front | 1 |
2d4140 Axle Gp-Front-Part 1 Of 3
| 2D***40 | Axle Group-Front | 1 |
2d4140 Axle Gp-Front-Part 3 Of 3
| 2D***40 | Axle Group-Front | 1 |
3d2329 Hub Cap Assembly
| 3D***29 | Cap Group-Hub | 1 |
2d6400 Centershift Gp
| 2D***00 | Centershift Group; Centershift Group | 1 |
2d7900 Circle Gp-Part 2 Of 2
| 2D***00 | Circle Group | 1 |
2d7900 Circle Gp
| 2D***00 | Circle Group | 1 |
2y1760 Circle Gp-Part 2 Of 2
| 2Y***60 | Circle Group | 1 |
2y1760 Circle Gp-Part 1 Of 2
| 2Y***60 | Circle Group | 1 |
2d7900 Circle Gp-Part 1 Of 2
| 2D***00 | Circle Group | 1 |
Circle Reversing Mechanism
2y2280 Frame Gp
| 2Y***80 | Frame Group | 1 |
2y2875 Hood & Dash Gp
| 2Y***75 | Hood & Dash Group | 1 |
6d4430 Radiator Support Group
| 6D***30 | Support Group-Radiator | 1 |
1g1655 Front Wheels And Tires Group
| 1G***55 | Wheel & Tire Group-Front | 1 |
Cooling System
8n4457 Base Gp-Oil Filter
| 8N***57 | Base Group-Oil Filter; Base Group-Engine Oil Filter | 1 |
8n4457 Base Gp-Engine Oil Filter
| 8N***57 | Base Group-Oil Filter; Base Group-Engine Oil Filter | 1 |
2p6215 Cooler Gp-Engine Oil
| 2P***15 | Cooler Group-Engine Oil; Oil Cooler Group Engine | 1 |
2y8054 Cooler Gp-Filter & Engine Oil
| 2Y***54 | Cooler Group-Filter & Engine Oil | 1 |
2w6953 Cooler Gp-Filter Base & Engine Oil
| 2W***53 | Cooler Group-Filter Base & Eng Oil | 1 |
2w6954 Cooler Gp-Filter Base & Engine Oil
| 2W***54 | Cooler Group-Filter Base & Eng Oil | 1 |
2y8053 Cooler Gp-Filter Base & Engine Oil
| 2Y***53 | Cooler Group-Filter Base & Eng Oil; Cooler Gp-Filter Base & Engine Oil | 1 |
7s3739 Fan & Guard Gp-Blower
| 7S***39 | Fan Group-Blower | 1 |
2p8172 Housing & Regulator Gp
| 2P***72 | Housing & Regulator Group; Regulator And Housing Group | 1 |
7n7211 Lines Gp-Water
| 7N***11 | Lines Group-Water; Water Lines Group | 1 |
8n4112 Lines Gp-Water
| 8N***12 | Lines Group-Water; -Bypass Relief | 1 |
2p7740 Lines Gp-Water
| 2P***40 | Lines Group-Water; Water Lines Group--Elbow | 1 |
2y8079 Lines Gp-Water
| 2Y***79 | Lines Group-Water; Water Lines Group | 1 |
7n5909 Water Pump Group
| 7N***09 | Pump Group-Water; Water Pump Group | 1 |
7n5909 Pump Gp-Water
| 7N***09 | Pump Group-Water; Water Pump Group | 1 |
2w8001 Pump Gp-Water*R
| 2W***01 | Pump Group-Water | 1 |
2p8195 Radiator Gp-Rear View-Part 2 Of 2
| 2P***95 | Radiator Group | 1 |
2p8195 Radiator Gp-Side View-Part 1 Of 2
| 2P***95 | Radiator Group | 1 |
Engine Arrangement
2y5175 Engine Ar-Part 2 Of 2
| 1P***44 | Breather Group | 1 |
| 2P***15 | Cooler Group-Engine Oil; Oil Cooler Group Engine | 1 |
| 2P***75 | Filter Group-Engine Oil; Oil Filter Group (10z1 ~ 10z7023) | 1 |
2y5175 Engine Ar-Part 1 Of 2
| 1N***06 | Camshaft Group-Single; Camshaft Group--Single | 1 |
| 2P***29 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
| 2P***99 | Fastener Group-Oil Pan; Oil Pan Fastener Group | 1 |
Fuel System And Governor
2y5993 Control Gp-Governor
| 2Y***93 | Control Group-Governor | 1 |
2y9252 Cover As
| 2Y***52 | Cover As | 1 |
2y6115 Cover Gp-Governor
| 2Y***15 | Cover Group-Governor | 1 |
2y8982 Cover Gp-Governor & Detent
| 2Y***82 | Cover Group-Governor & Detent | 1 |
1p2299 Filter As-Fuel
| 1P***99 | Filter As-Fuel; (Advanced Efficiency)(Secondary) | 1 |
2y8670 Filter As
| 2Y***70 | Filter As-Fuel | 1 |
2y5711 Filter Gp-Fuel
| 2Y***11 | Filter Group-Fuel; Fuel Filter Group | 1 |
2y8980 Flyweight Gp
| 2Y***80 | Flyweight Group | 1 |
2y6518 Flyweight Gp
| 2Y***18 | Flyweight Group | 1 |
2y6160 Governor Gp-Part 2 Of 2
| 2Y***60 | Governor Group | 1 |
2y6160 Governor Gp-Part 1 Of 2
| 2Y***60 | Governor Group | 1 |
5y1157 Governor Gp-Part 1 Of 2
| 5Y***57 | Governor Group | 1 |
2y6160 Governor Gp- Part 2 Of 2
| 2Y***60 | Governor Group | 1 |
2y8993 Governor Gp-Part 2 Of 2
| 2Y***93 | Governor Group | 1 |
2y8993 Governor Gp-Part 1 Of 2
| 2Y***93 | Governor Group | 1 |
5y1157 Governor Gp-Part 2 Of 2
| 5Y***57 | Governor Group | 1 |
2y6105 Governor Gp
| 2Y***05 | Governor Group | 1 |
2y5709 Fuel Injection Lines Group
| 2Y***09 | Lines Group | 1 |
2y5907 Lines Gp-Fuel
| 2Y***07 | Lines Group-Fuel | 1 |
2y5708 Lines Gp-Fuel Injection
| 2Y***08 | Lines Group-Fuel Injection; Fuel Injection Lines & Mounting Gp | 1 |
2y5708 Fuel Injection Lines & Mounting Gp
| 2Y***08 | Lines Group-Fuel Injection; Fuel Injection Lines & Mounting Gp | 1 |
2y5712 Lines Gp-Injection Pump Lube Oil
| 2Y***12 | Lines Group-Lube Oil; Injection Pump Lubrication Oil Lines Grp | 1 |
2y5800 Pump Gp-Fuel Injection-Part 2 Of 2
2y5800 Governor & Fuel Injection Pump Gp-Part 2 Of 2
| 2Y***00 | Pump Group-Fuel Injection | 1 |
2y5800 Governor & Fuel Injection Pump Gp-Part 1 Of 2
| 2Y***00 | Pump Group-Fuel Injection | 1 |
2y5800 Pump Gp-Fuel Injection-Part 1 Of 2
| 2Y***00 | Pump Group-Fuel Injection | 1 |
2y5787 Pump Gp-Fuel Transfer
| 2Y***87 | Pump Group-Fuel Transfer | 1 |
2y8994 Governor & Fuel Injection Pump Gp
| 2Y***94 | Pump Group-Gov & Fuel Inj; Governor & Fuel Injection Pump Gp | 1 |
2y5716 Governor And Fuel Injection Pump Gp
| 2Y***16 | Pump Group-Gov & Fuel Inj; Governor And Fuel Injection Pump Group | 1 |
5y1156 Governor,Fuel Injection & Fuel Transer Pump Gp
| 5Y***56 | Pump Group-Gov, Fuel Inj & Tfr; Governor & Fuel Injection Pump Gp | 1 |
2y6133 Rack Gpoup
| 2Y***33 | Rack Setting Group | 1 |
2y9250 Setting Gp
| 2Y***50 | Setting Group | 1 |
2y6158 Shim Group-Calibration Set
| 2Y***83 | Shim--10 mm (0.40 In. Thick) | 6 |
| 2Y***84 | Shim--11 mm (0.45 In. Thick) | 6 |
| 2Y***85 | Shim--13 mm (0.50 In. Thick) | 6 |
Implements
2y2260 Blade Ar-Power-Type 2
| 2Y***60 | Circle Group | 1 |
| 2Y***50 | Valve & Lines Group | 1 |
| 2Y***60 | Blade Ar-Power | 1 |
2y2260 Blade Ar-Power-Type 1
| 2Y***56 | Boss Group | 1 |
| 2Y***60 | Circle Group | 1 |
| 2Y***50 | Valve & Lines Group | 1 |
5d4790 Blade Gp
| 5D***90 | Blade Group; Blade Group | 1 |
1g2227 Blade Gp-Type 1
| 1G***27 | Blade Group | 1 |
1g2227 Blade Gp-Type 2
| 1G***27 | Blade Group | 1 |
1g2227 Blade Gp
| 1G***27 | Blade Group | 1 |
6d3300 Scarifier Gp-Part 2 Of 3
| 6D***00 | Scarifier Group | 1 |
6d3300 Scarifier Gp-Part 1 Of 3
| 6D***00 | Scarifier Group | 1 |
6d3300 Scarifier Gp-Part 3 Of 3
| 6D***00 | Scarifier Group | 1 |
4d8510 Support Gp-Blade Bracket
| 4D***10 | Support Group-Blade Bracket | 1 |
Lubrication System
1p4244 Breather Group
| 1P***44 | Breather Group | 1 |
2p6199 Fastener Gp-Oil Pan
| 2P***99 | Fastener Group-Oil Pan; Oil Pan Fastener Group | 1 |
2p6855 Filler Gp-Engine Oil
| 2P***55 | Filler Group-Oil | 1 |
2p6475 Filter Gp-Oil
| 2P***75 | Filter Group-Engine Oil; Oil Filter Group (10z1 ~ 10z7023) | 1 |
2y6278 Fumes Disposal Group
| 2Y***78 | Fumes Disposal Group; Fumes Disposal Group | 1 |
2y8416 Gauge Gp-Oil Level (Dipstick)
| 2Y***16 | Gauge Group-Oil Level (Dipstick) | 1 |
2p6493 Gauge Gp-Oil Level (Dipstick)
| 2P***93 | Gauge Group-Oil Level (Dipstick); -Engine | 1 |
2p6861 Lines Gp-Engine Oil
| 2P***61 | Lines Group-Engine Oil; Engine Oil Lines Group | 1 |
2y5231 Oil Pan Group
| 2Y***31 | Pan Group-Oil | 1 |
2p7830 Gear Pump Group
| 2P***30 | Pump Group-Gear | 1 |
2p6537 Pump Gp-Oil
| 2P***37 | Pump Group-Oil; Engine Oil Pump Group | 1 |
Power Train-Power Transmission Unit
7d7630 Rear Axle Group
| 7D***30 | Axle Group-Rear | 1 |
4d2150 Transmission Brake Group
| 4D***50 | Brake Group-Transmission | 1 |
5d3400 Transmission Case And Covers Group-Side View
| 5D***00 | Case & Covers Group-Tmsn | 1 |
5d3400 Transmission Case And Covers Group-End View
| 5D***00 | Case & Covers Group-Tmsn | 1 |
6d1590 Clutch Gp-Flywheel
| 6D***90 | Clutch Group-Flywheel | 1 |
7d5460 Filter Gp-Oil
| 7D***60 | Filter Group-Oil | 1 |
7d9550 Transmission Lubrication System Group
| 7D***50 | Lubrication Group-Transmission | 1 |
4d2790 Shift Gp-Gear
| 4D***90 | Shift Group-Gear | 1 |
4d3300 Transmission Gp-Part 2 Of 4
| 4D***00 | Transmission Group | 1 |
4d3300 Transmission Gp-Part 3 Of 4
| 4D***00 | Transmission Group | 1 |
4d3300 Transmission Gp-Part 1 Of 4
| 4D***00 | Transmission Group | 1 |
4d3300 Transmission Gp-Part 4 Of 4
| 4D***00 | Transmission Group | 1 |
1g1660 Wheel & Tire Gp-Rear
| 1G***60 | Wheel & Tire Group-Rear | 1 |
Service Equipment And Supplies
Gasket Kits
| 5P***68 | Kit-Gasket; (Single Cylinder Liner)(Single Cylinder Liner) | 0 |
| 5P***98 | Valve Grinding; - Serial No. 3n55880 To 3n79762 Inclusive | 0 |
| 5P***02 | 8n***60, 8n***61, 8n***15, 8n***16; 1w***78, 1w***79, 1w***86, 1w***87 | 0 |
Name Plates And Transfers
| 1G***08 | Plate-Instruction-On Instrument Panel | 1 |
| 1G***47 | Plate-Gearshift-Under Instrument Panel | 1 |
| 1G***83 | Cap-Grease | 74 |
Starting And Electrical System
2y8310 Alternator Gp
| 2Y***10 | Alternator Group-Charging | 1 |
2y4212 Alternator Gp
| 2Y***12 | Alternator Group-Charging | 1 |
2y8945 Alternator Gp
| 2Y***45 | Alternator Group-Charging | 1 |
2y2935 Alternator Gp
| 2Y***35 | Alternator Group-Charging | 1 |
2y1955 Battery & Wiring Gp-Part 3 Of 5
| 2Y***55 | Battery & Wiring Group | 1 |
2y1955 Battery & Wiring Gp-Part 1 Of 5
| 2Y***55 | Battery & Wiring Group | 1 |
2y1955 Battery & Wiring Gp-Part 5 Of 5
| 2Y***55 | Battery & Wiring Group | 1 |
2y1955 Battery & Wiring Gp-Part 2 Of 5
| 2Y***55 | Battery & Wiring Group | 1 |
2y1955 Battery & Wiring Gp-Part 4 Of 5
| 2Y***55 | Battery & Wiring Group | 1 |
5s8501 Glow Plug Group
| 5S***01 | Glow Plug Group; Glow Plug And Wiring Group | 1 |
2y2074 Harness Assembly
| 2Y***74 | Harness As | 1 |
7m7147 Lamp As-Stop & Tail
| 7M***47 | Lamp As-Stop & Tail | 1 |
1m3387 Dash Lamp Assembly-24 Volt
| 1M***87 | Lamp Group | 1 |
1m6052 Head Lamp Assembly-24 Volt
| 1M***52 | Lamp Group | 1 |
2y1780 Lamp Gp-Head
| 2Y***80 | Lamp Group-Head | 1 |
2y2930 Regulator As
| 2Y***30 | Regulator As; (Separate Illustration) | 1 |
2y1921 Starting Motor Gp-Electric
| 2Y***21 | Starting Motor Group-Electric | 1 |
2y1920 Starting Motor Gp-Electric
| 2Y***20 | Starting Motor Group-Electric | 1 |
2y8441 Switch As-Disconnect
| 2Y***41 | Switch As-Disconnect | 1 |
7n0718 Switch As-Disconnect
| 7N***18 | Switch As-Disconnect; -Battery-Ground Level | 1 |
7n4160 Switch Gp
| 7N***60 | Switch Group | 1 |
3306 serial number reference
The 3306 serial/PIN plate is a stamped metal tag mounted on the engine block, usually on the right side near the flywheel housing or valve cover; if the plate is missing or damaged, the number is also stamped directly into the block in that same area. Read it as a 3-character prefix (letters and numbers) followed by a sequential number - the prefix pins down the specific engine arrangement (generator set, industrial power unit, marine, truck, or machine-fit) rather than a model year, so match it against Cat arrangement records or a dealer to confirm the exact configuration and approximate build era.
| Prefix | Identifies | Notes |
|---|---|---|
| 2ZC | 3306 generator set engine | Prefix for a 3306 diesel engine built for generator-set duty. |
| 5JC | 3306 generator set engine | Prefix for a 3306 diesel engine built for generator-set duty. |
| 7HB | 3306 generator set engine | Prefix for a 3306 diesel engine built for generator-set duty. |
| 7KF | 3306 generator set engine | Prefix for a 3306 diesel engine built for generator-set duty. |
| 85Z | 3306 generator set engine | Prefix for a 3306 diesel engine built for generator-set duty. |
| 23C | 3306 industrial engine | Industrial power-unit application (driving pumps, compressors, or similar equipment), not mounted in a Cat wheeled or tracked machine. |
| 4WB | 3306 industrial engine | Industrial power-unit application, not mounted in a Cat wheeled or tracked machine. |
| 64Z | 3306 industrial / machine-fit engine | Shows up on both the industrial power-unit list and the Cat machine engine-fit list for the 3306; exact host not specified. |
| 66D | 3306 industrial engine | Pure industrial power unit; documented as never fitted to a wheeled or tracked Cat machine. |
| 70R | 3306 industrial engine | Industrial power-unit application, not mounted in a Cat wheeled or tracked machine. |
| 67D | 3306 marine engine | Marine propulsion application. |
| 84Z | 3306 marine engine | Marine propulsion application. |
| 63Z | 3306 truck (on-highway) engine | On-highway truck vehicular engine application. |
| 69D | 3306 truck (on-highway) engine | On-highway truck vehicular engine application. |
| 76R | 3306 truck (on-highway) engine | On-highway truck vehicular engine application. |
| 3CF | 3306 natural gas engine variant | Dealer serial-prefix charts list this prefix as a 3306 gas engine, but a separate manual title ties the same prefix to the G3306 gas engine, a distinct natural-gas model built off the same block. Confirm which gas variant applies with your dealer before ordering parts. |
| 03N | 3306 machine-fit engine | Cat 3306 vehicular engine serial prefix (also shown as 3N). This engine-serial range covers several different machine hosts through different engine arrangement numbers, with documented ties to the Cat 12G motor grader, D5/D6/D6C track-type tractors, and 235 hydraulic excavator. Confirm the arrangement number with your dealer to pin the exact host. |
| 08Z | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented in available references - confirm with dealer. |
| 10Z | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 13Z | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 1AF | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 1TF | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 2JG | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 2KJ | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 3CK | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 44V | 3306 machine-fit engine | Grouped with the Cat 235 excavator engine option in a parts listing; confirm with dealer. |
| 47V | 3306 machine-fit engine | Grouped with the Cat 235 excavator engine option in a parts listing; confirm with dealer. |
| 49V | 3306 machine-fit engine | Engine arrangement fitted to the Cat 235 hydraulic excavator, serial 49V12554 and up. |
| 5SF | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 60Z | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 62Z | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| 6NC | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; a single source loosely tied it to the Cat D7F track-type tractor but that could not be independently confirmed, and the D7F's own serial number chart references a different prefix for its engine range. Treat host as undocumented - confirm with dealer. |
| 8TD | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
| R6J | 3306 machine-fit engine | Listed on a Cat machine engine-prefix reference under the 3306; specific host machine model not documented - confirm with dealer. |
Frequently asked questions
What engine is the Caterpillar 3306?
It's Caterpillar's own design: a mechanically governed, 10.5-liter (638 cu in) inline six-cylinder diesel with a 121 mm bore and 152 mm stroke. Caterpillar built it as a bare industrial, marine, and generator-set engine in naturally aspirated, turbocharged, and turbocharged-aftercooled versions — it has no chassis or undercarriage of its own, and no electronic control module; fuel delivery and governing are fully mechanical.
What does a Caterpillar 3306 weigh?
Dry weight runs roughly 1,020-1,400 kg (2,250-3,090 lb), depending on configuration. Aftercooler, marine gear, cooling package, and flywheel housing all add to the base engine weight, so check the accessory list on your specific unit rather than assuming one figure.
What replaced the Caterpillar 3306?
Caterpillar moved industrial and generator-set customers to its electronically controlled C9 and C7 engines as emissions standards tightened, with some on-highway roles shifting earlier to the 3126 family. Exact timing varies by application and market — the 3306 stayed in marine and stationary catalogs well after electronic engines took over mobile equipment.
What 3306 owners discuss
What causes a 3306 to be hard to start after sitting idle for a few days?
The recurring complaint is 30+ seconds of cranking with a no-fuel feel on first start. Root cause is usually a weak fuel transfer pump letting pressure bleed down overnight, air pulled in past a leaking fuel filter housing seal, or a fuel shutoff solenoid not fully retracting. Some owners add an inline lift pump to restore priming pressure rather than replace the injection pump outright. Check fuel lines and the filter housing for air ingress before condemning the pump. Have your dealer verify fuel system pressure and solenoid operation.
Why does a 3306 PC injection pump go out of time so easily, and how is it retimed?
Two pump styles are in the field and they time differently. The early scroll-type PC pump has no timing marks on the pump body itself; it must be set with a timing fixture referenced off the crank and cam marks. The later sleeve metering pump, identified by a large plate on its side, can be pin-timed using a 6.35 mm (1/4 in.) drill bit as the pin. Owners repeatedly trace hard starting and rough running after pump service back to timing slip, especially if oil got onto the tapered mounting surface during reassembly. Have your dealer verify final timing with the correct fixture for your pump style.
Does turbo or aftercooler configuration change what fails on a 3306, and does the power rating matter?
The 3306 was built naturally aspirated, turbocharged, and turbo-aftercooled, with the same basic block rated anywhere from roughly 110-220 kW (150-300 hp) depending on configuration and application; treat any single number as varying by series. On T/TA versions, the turbo itself rarely fails outright; most reported turbo problems trace back to a torn charge-air boot or loose clamp leaking boost rather than worn bearings, though bearing noise or shaft play is worth checking around 7,000-7,500 hours. On water-to-air aftercooled versions, scale buildup inside the aftercooler core from poor coolant maintenance is the most repeated failure, cutting intake cooling before the turbo itself wears out. On power rating, a 3306 running around 150 kW (200 hp) is regarded as very durable for industrial and genset duty, while the same block pushed toward the top of its rating band in some mobile applications has a history of piston failures, so treat the upper end of the range as less forgiving of sustained full load. Have your dealer verify boost pressure and aftercooler flow if power feels down, and confirm the rating plate matches your duty cycle before repowering.
What engine wear pattern typically shows up as high oil consumption on a 3306?
Owners describe visible smoke on acceleration and deceleration along with oil disappearing faster than expected, usually tied to worn valve guides, glazed liners, or a partial repair that replaced only the rings or only the liners instead of doing both together. The standard diagnostic is pulling the valve cover to look for soot staining around the guides, and pressurizing the intake manifold to check for blowby past the intake valve seals. A rebuild that skips one half of the liner/ring/guide set is repeatedly flagged as the reason oil consumption returns soon after. Have your dealer verify compression and blowby volume before committing to an inframe overhaul.
What electrical or sensor issues come up most often on the 3306?
The most repeated complaint is a fuel shutoff solenoid that sticks or drops out intermittently, and in most cases the coil itself is fine; corroded terminal connections or brittle wire insulation shorting to ground is the actual fault. On rack and timing sensor circuits, wiring routed near the keyswitch harness is called out as prone to chafing, producing an intermittent no-start or random shutdown that mimics a fuel problem. The standard field check is to listen for the solenoid click at key-on, then try starting with the solenoid unplugged or pulled; if it starts, the fault is in the solenoid or its wiring, not the injection pump. Have your dealer verify wiring continuity and solenoid voltage before replacing fuel system components.
What is the common overheating complaint on marine 3306 installations?
In heat-exchanger-cooled marine installs, the recurring cause is reduced raw water flow: a collapsed suction hose, growth or debris fouling the strainer, a worn raw water pump impeller, or a heat exchanger core clogged with old zinc fragments and scale. Rodding out the heat exchanger tubes and replacing the impeller and zincs on a set interval is the most repeated preventive step. Owners also note that removing the thermostat to cure overheating backfires, since the thermostat closing is what forces coolant through the exchanger; pulling it makes overheating worse, not better. This applies to heat-exchanger/keel-cooled marine setups specifically and does not carry over to radiator-cooled industrial installs. Have your dealer verify raw water flow rate and heat exchanger condition rather than adjusting coolant mix alone.
What should I check before buying a used 3306?
Get full hours and service records rather than trust the hour meter alone, and for gensets ask for documentation of a completed load test. Inspect the control panel and wiring for corrosion, and confirm the correct radiator or heat exchanger package is fitted and functional for the application. Verify the aspiration configuration, naturally aspirated, turbocharged, or turbo-aftercooled, off the rating plate rather than assuming it from the machine it is pulled from, since power ratings vary widely across configurations on the same block. Budget for injection pump service through a Cat dealer, since that work is not generally DIY-friendly. Have your dealer verify compression, blowby, and injection pump condition with a proper inspection before you buy.
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 3306. Related factory variants of the same model family:
3306330633063306
Need a specific 3306 part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.