The Cummins/Onan CCK is a 2-cylinder natural engine rated at 1500 rpm. It powers generator sets from Cummins/Onan, including the 3.5CCK, 4.0CCK and 5.0 CCK. It holds 2.8 L (0.7 gal) of oil.
Also known as: Onan CCK
Part of the Cummins/Onan CCK engine family — 3 variants share parts & fitment.
| Oil capacity | 2.8 L |
|---|---|
| Cylinders | 2 |
| Aspiration | Natural |
| Rated speed | 1500 rpm |
How to read your Cummins/Onan engine serial & model number →
| Symptom | Cause | Remedy |
|---|---|---|
| The speed may remain about the same or increase when the load is applied, resulting in a frequency 1 or 2-cycles Aigker than the no load frequency. | If the rise in frequency is more than 2-cycles, lessen the internal spring tension. If there is a drop in the frequency, increase the booster internal spring tension. To increase the tension, pull out on the spring bracket, and move the pin to a different hole. | |
| Engine will not start when cranked | Battery discharged. Loose connections. Defective starting circuit. Defective switch. | Refill tank. Check fuel system. Clean, adjust, as necessary. Crank few times with spark plugs removed. Drain, refill with fresh fuel. Tighten cylinder heads & spark plugs. Reset breaker points. |
| Engine cranks too stiffly | Too heavy oil in crankcase. | Drain, refill with lighter oil. |
| Hot crank | Lack of fuel or faulty carburetion. | Tighten connections. Clogged fuel screen. Repait or replace as necessary. Cylinders flooded. Replace. Poor fuel. Poor compression. |
| Excessive oil consumption, light blue smoky exhaust | Oil leaks from oil base or connections, This does not cause smoky exhaust. | Check breather valve. |
| Engine misfiring. | Faulty ignition. | Clean, adjust, or replace spark plugs. |
| BLACK, SMOKY EXHAUST, EXCESSIVE FUEL CONSUMPTION, FOUCING OF SPARK PLUG WITH SOOT, POSSIBLE LACK OF POWER UNDER HEAVY LOAD | Fuel mixture too rich. | Adjust carburetor or choke. Install needed carburetor parts. |
| Engine stops unexpectedly. | Fuel tank empty. | Fill with fresh fuel. |
| SHARP METALLIC THUD, ESPECIALLY WHEN COLD ENGINE FIRST STARTED | Low oil supply. | Add oil. |
| Oil badly diluted. | Change oil. | |
| PINGING SOUND WHEN ENGINE IS SUDDENLY OR HEAVILY LOADED! | Wrong spark plug. | Install correct spark plug. |
| Spark plug burned or carboned. | Install new plug. | |
| Fuel stale or low octane. | Use good, fresh fuel. | |
| LEAN FUEL MIXTURE. | Clean or adjust carburetor. Clean intake air line. | |
| LIGHT POUNDING KNOCK | Inspect linkage and setting. | Clean & adjust carburetor. |
| Low air supply. | Add oil. Change oil. | |
| ENGINE MISFIRES AT LIGHT LOAD | Spark plug gap too narrow. | Adjust to correct gap. Tighten or replace manifold and carburetor gaskets. |
| INTAKE AIR LEAK. | Tighten or replace manifold and carburetor gaskets. | |
| FAULTY IGNITION. | Clean, adjust or replace spark plugs. Tighten cylinder head & spark plugs. Grind valves. | |
| LOW COMPRESSION. | Tighten cylinder head & spark plugs. Grind valves. | |
| ENGINE MISFIRES AT HEAVY LOAD | Spark plug gap too wide | Adjust gap |
| CLOGGED CARBURETOR. | Clean, adjust or replace spark plugs. Clean jet and adjust carb. | |
| CLOGGED FUEL SCREEN. | Clean, adjust or replace spark plugs. Clean jet and adjust carb. | |
| ENGINE BACKFIRES | Lean fuel mixture. | Clean or adjust carburetor. |
| ENGINE RACES | Governor not controlling carburetor. | Check governor performance & linkage condition. Refill with good, fresh fuel. |
| LOW OIL PRESSURE | Defective gage. | Replace. |
| Oil too light or diluted from leaking fuel pump diaphragm. | Drain. Refill with proper oil. Repair or replace fuel pump. | |
| Oil taa low. | Add oil. | |
| Sludge on oil cup screen. | Clean screen & air sump. | |
| Badly worn oil pump. | Replace. | |
| HIGH OIL PRESSURE | Defective gage. | Replace. |
| Oil too heavy grade. | Drain. Refill. | |
| Clogged oil passages. | Clean all lines & passages. | |
| Oil relief valve stuck. | Clean by-pass. Replace if needed. | |
| ENGINE OVERHEATING (Approximasely 60°F higher than ambient) | Overloaded. | Reduce load. |
| VOLTAGE LOW AT FAR END OF LINE BUT NORMAL NEAR POWER PLANT | Too small line wire for load and distance. | Install larger or extra wires. Or reduce load. |
| ELECTRIC MOTOR RUNS TOO SLOWLY AND OVERHEATS AT FAR END OF LINE BUT OK IF USED NEAR POWER UNIT | Too small line wire for load and distance. | Install larger or extra wires. Or reduce load. |
| VOLTAGE UNSTEADY BUT ENGINE NOT MISFIRING | Speed too low. | Adjust governor to correct speed. |
| Loose connections. | Tighten connections. | |
| Correct any abnormal load condition causing trouble. | Write a letter to the same address stating the reason for returning the part. |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan CCK.
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | Element, Air Cleaner | 140P837 | Amazon eBay | ||
| Oil filter | Element, Oil Filter | 122-75 | Amazon eBay | ||
| Belt | Belt, Alternator | 511-76 | Amazon eBay | ||
| Fuel | Fuel system and pump | — | |||
| Oil | API SE or SE/CC | 3.79 liters | — | 200 hr | |
| Spark plug | Gasoline engines | — | 30 hr |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Step-by-step procedures compiled from the Cummins/Onan service manual for this engine.
| Part # | Description | Category |
|---|---|---|
| 140B495 | Air Cleaner Element | air_filter |
| 140P837 | Element, Air Cleaner | air_filter |
| 511-76 | Belt, Alternator | belt |
| 514-51 | Belt, Charge Generator Drive | belt |
| 149-0751 | Electric Shutoff Valve | electric_shutoff_valve |
| 149-149 | Filter, Fuel | fuel_filter |
| 149-150 | Bowl, Fuel Filter | fuel_filter |
| 149-0558 | Fuel Strainer | fuel_strainer |
| 101K115 | Gasket Kit, Rear Bearing Plate | gasket |
| 102-0158 | Gasket, Oil Base | gasket |
| 102B158 | Gasket, Oil Base | gasket |
| 103B1 | Gasket, Gear Cover | gasket |
| 103B11 | Gasket, Gear cover | gasket |
| 110A667 | Gasket, Valve Cover | gasket |
| 110A892 | Gasket, Cylinder Head | gasket |
| 110B880 | Gasket, Fuel Pump Hole Cover | gasket |
| 110D883 | Gasket, Cylinder Head Left #1 Hi-Comp | gasket |
| 110D884 | Gasket, Cylinder Head Right #2 Hi-Comp | gasket |
| 110D890 | Gasket, Cylinder Head Right #2 | gasket |
| 110D891 | Gasket, Cylinder Head Left #1 | gasket |
| 120A491 | *Gasket, Diaphragm | gasket |
| 120K161 | Gasket Kit, Oil Pump | gasket |
| 123A104 | Gasket, Oil Fill Tube | gasket |
| 123A191 | Gasket, Oil Fill Cap | gasket |
| 141A78 | Carburetor Flange Gasket | gasket |
| 142-31 | Gasket, Body to Bowl | gasket |
| 142-32 | Gasket, Nozzle | gasket |
| 142-33 | *Gasket Kit, Carburetor | gasket |
| 142-361 | Gasket, Nozzle | gasket |
| 142-49 | *Valve and Seat Assembly, Float - Includes Gasket ........•...•.. | gasket |
| 145B266 | Gasket, Carburetor Adapter to Manifold | gasket |
| 148A17 | @Gasket, Bushing - Float Lock. | gasket |
| 148A22 | Gasket, Adapter Mounting | gasket |
| 149A3 | Gasket, Fuel Pump Mtg. 45 502-3 ! Connector, Fue! Filter | gasket |
| 149A858 | Gasket, Diaphragm | gasket |
| 149A95 | Gasket, Valve | gasket |
| 150A425 | Gasket, Booster to Manifold | gasket |
| 150A668 | Gasket, Diaphragm Plate | gasket |
| 154A13 | Gasket, Intake Manifold | gasket |
| 154A360 | Gasket, Carburetor Mounting | gasket |
| 154C377 | Gasket, Exhaust Manifold or Muffler Mounting | gasket |
| 160A150 | Gasket, Breaker Box Cover | gasket |
| 160A43 | Gasket, Breaker Box Mounting | gasket |
| 160A723 | Gasket, Breaker Box and Spacer Mounting | gasket |
| 168K103 | Gasket Kit, Plant | gasket |
| 168K67 | Gasket Kit, Plant (Repl. 16aK103) | gasket |
| 168K88 | Gasket Kit, Complete Engine | gasket |
| 518-129 | *Gasket, Fuel Pump Mounting | gasket |
| 168K95 | Gasket Kit, Carbon Removal | gasket_kit |
| 501A118 | Line, Flexible Oil | hose |
| 501A9 | Line, Flexible Fuel | hose |
| 503A480 | Hose, Air Cleaner | hose |
| 122-37 | Cartridge, Oil Filter | oil_filter |
| 122-75 | Element, Oil Filter | oil_filter |
| 122C9 | Filter, Oil - Includes Cartridge (Optional) | oil_filter |
| 160A2 | Point Set, Breaker | other_service |
| 160A75 | 160A 150 | other_service |
| 201-1312 | Rotor Assembly, Wound | other_service |
| 222-1675 | Coil Assembly, Field | other_service |
| 312A69 | Condenser | other_service |
| 800-0007 | Plug, Oil Drain | other_service |
| 801-0048 | Screw, Oil By-Pass Valve | other_service |
| 148-0034 | Pressure Reducing | pressure_reducing |
| 120-0413 | Cup, Oil Pump Intake | pump |
| 120-0491 | Pump, Oil | pump |
| 120A187 | Pump - Includes Cup, Screen and Pipe | pump |
| 149D693 | Pump, Fuel - ONAN mfr., with primer lever - Replaces earlier atyle pumps used, of any manufacture | pump |
| 149A404 | Seal, 'O' Ring | seal |
| 509-0040 | Seal, Oil - Crankshaft | seal |
| 509-65 | 149A1042 | seal |
| 509-8 | Seal, Governor Shaft Oil | seal |
| 509-9 | Seal, "O" Ring | seal |
| 509A40 | *Seal, Gear Cover | seal |
| 509A41 | Seal, Bearing Plate | seal |
| 509A97 | Seal, Oil - Gear Cover | seal |
| XA-744AN | Seal, 'O' Ring | seal |
| 193A108 | Element, Oil Pressure | sensor |
| 167-177 | Plug, Spark | spark_plug |
| 167-241 | Plug, Spark | spark_plug |
| 134B660 | Element, Vernatherm | thermostat |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.
The Cummins/Onan CCK engine has an oil capacity of 2.8 liters.
The Cummins/Onan CCK powers 3 generator set(s), including Cummins/Onan 3.5CCK, Cummins/Onan 4.0CCK, Cummins/Onan 5.0 CCK.
The Cummins/Onan CCK oil change interval is every 200 hours.
A commonly reported issue on generators using the Cummins/Onan CCK is: Low or Discharged Battery. Fix: Faulty Starter, Faulty Start Solenoid.