Specifications
Ratings spec sheet not in our library yet — see the documents below.
Filters & service parts
model family| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | unloader valves | 3375049 | 6000 hr | PartsGeek | |
| Fuel filter | 3810432 | 6000 hr | PartsGeek | ||
| Oil filter | Apply grease to both of the cylinder extension rods (6) and (10). Apply grease to the side of the roller tappets (8) to lubricate the tappets and the bushings. | 3375049 | 6000 hr | PartsGeek | |
| Belt | Install the fan belt idler assembly, the three lock washers and capscrews. | — | 6000 hr | find | |
| Coolant | 6.8 L | — | 1500 hr | ||
| Coolant filter | 3822648/3823348 | 6000 hr | PartsGeek | ||
| Oil | Military Specification MIL-L-644, Type P-9 | 45.0 L | — | 6000 hr |
Compiled from this model's family documentation — may include parts for closely-related variants. Confirm the exact part for your serial number.
Common questions
What oil filter does the Cummins/Onan K38 use?
The Cummins/Onan K38 uses oil filter part number 3375049.
What fuel filter does the Cummins/Onan K38 use?
The Cummins/Onan K38 uses fuel filter part number 3810432.
What air filter does the Cummins/Onan K38 use?
The Cummins/Onan K38 uses air filter part number 3375049.
Troubleshooting
25Symptoms & remedies
| Symptom | Cause | Remedy |
|---|---|---|
| Engine Will Not Crank or Cranks Slowly (Air Starter) | Incorrect Oil For Operating Conditions, Oil Temperature Too Low, Insufficient Air Pressure, Starter Malfunction or Incorrect Starter, External or Internal Conditions Affecting Engine Crankshaft Rotation | Change oil and filters. Use recommended type (15W-40), Install oil pan heater, Increase pressure using external air supply, Refer to manufacturer's instructions, Check engine for ease of crankshaft rotation |
| Engine Will Not Crank or Cranks Slowly (Electric Starter) | External or Internal Conditions Affecting Engine Crankshaft Rotation, Battery Connections. Broken, Loose or Corroded, Incorrect Oil, Oil Temperature Low, Battery Rating Too Low, Battery Temperature Too Low, Battery Charge Low, Starting Circuit Component Malfunction | Check engine for ease of crankshaft rotation, Check battery connections, Refer to Section A, Change oil and filters. Use recommended type (15W-40), Install oil pan heater, Replace with correct rating, Check battery heater operation, Check starting circuit components |
| Engine Hard to Start or Will Not Start (Exhaust Smoke Present) | Engine Cranking Speed Low (Below 150 RPM), Engine Driven Units Engaged, Cold Start Aid Needed or Not Working Correctly, Fuel Filter Plugged, Air in the Fuel System, Fuel Suction Line Restricted, Intake Air System Restricted, Fuel Contaminated | Check engine cranking RPM, Disengage engine driven units, Install cold start aid. Check, repair, or replace if necessary, Replace fuel filter, Check for air in fuel, tighten fuel connections and filter, check fuel tank stand pipe, Check fuel line for restrictions, Check intake air system for restrictions |
| Engine Cranks But Will Not Start (No Smoke From Exhaust) | No Fuel In Tank, Shut-off Valve Closed, No Fuel To Injectors, Air In The Fuel System, Engine Driven Units Engaged, Fuel Filter Plugged or Suction Line Restricted, Fuel Contaminated, Intake or Exhaust System Restricted | Add fuel, Use manual override. Repair electrics, Check for fuel, Tighten all fuel filter fittings and connections from fuel tank to fuel pump, Replace fuel filter, Inspect fuel hose for restriction, Verify by operating engine from a temporary supply tank, Check intake and exhaust system for restrictions |
| Engine Starts But Will Not Keep Running | Air In The Fuel System, Engine Driven Units Engaged, Fuel Filter Plugged or Fuel Waxing Due to Cold Weather, Fuel Suction Line Restricted, Fuel Contaminated, Intake or Exhaust System Restricted | Check for air in fuel, tighten fuel connections, tighten filter, check fuel tank stand pipe, Disengage engine driven units, Replace fuel filter. Weather conditions can require fuel heater, Inspect fuel line for restriction, Verify by operating engine from a temporary supply tank, Check intake and exhaust system for restrictions |
| Engine Will Not Shut Off | Fuel Pump Manual Override Open, Fuel Pump Shut-off Valve Disc Stuck, Fuel Tank Vents Plugged, Fuel Drain Line Restricted, Engine Running on Fumes Drawn into Air Intake | Check to make sure manual override screw is out to maximum travel, Check opening and closing of electrics, Remove, clean, or replace vents, Check fuel drain line for loops, crimps, clamped points, Locate and isolate the source of fumes |
| Lubricating Oil Pressure Low | Incorrect Oil Level, Incorrect Oil Specifications: Oil Diluted With Fuel, Oil Temperature Above Normal (120°C [250°F)) | Check for oil leaks. Add or drain engine oil. Refer to Section 5.: Check dipstick calibration. Refer to Section A, Change oil and check oil specifications, Refer to Coolant Temperature Above Normal Chart |
| Coolant Temperature Above Normal | Low Coolant Level | Add coolant |
| Radiator Shutters are not Opening Completely or Cold Weather | Radiator Cover Closed | Open yadiator cover |
| Coolant Temperature Below Normal | Radiator Shutters Stuck in Open Position or Opening Early | Inspect the shutters. Repair or replace if necessary. |
| Exhaust Smoke Excessive Under Load | Intake Air System Restricted | Check intake air system for restrictions. |
| Engine Power Output Low | Excessive Load for Engine Horsepower Rating | Reduce vehicle load. |
| Fuel Suction Line or Fuel Filter Restricted | Check fuel line for restriction. Replace fuel filter if necessary. | |
| Lubricating Oil Level Too High | Check dipstick calibration and oil pan capacity. Refer to Section A. | |
| Throttle Linkage Adjustment Wrong | Check throttle linkage adjustment for full opening of throttle lever. | |
| Intake or Exhaust System Restricted | Check intake and exhaust systems for restrictions. | |
| Fuel is Spongy Throttle is Stuck | Check for air in fuel, tighten fuel connections and filter, check fuel tank stand pipe. | |
| White Smoke or Rough Running At Idle (After Warmup Period) | Low Coolant Temperature | Refer to Coolant Temperature Below Normal chart. Verify by operating engine from a temporary tank that contains good fuel. |
| Engine Will Not Reach Rated Speed When Loaded | Excessive Load for Engine Horsepower Rating | Reduce load. |
| Tachometer Has a Malfunction | Check with hand or digital tachometer. | |
| Fuel Suction Line Restricted | Check fuel inlet for restriction. | |
| Engine Driven Units Engaged | Disengage engine driven units. | |
| Fuel Filter Plugged or Fuel Waxing Due to Cold Weather | Replace fuel filter. Weather conditions can require fuel heater. | |
| Fuel Contaminated | Verify by operating engine from a temporary supply tank. | |
| Air in Fuel - Spongy Throttle is Symptom | Check for air in fuel, tighten fuel connections and filter, check fuel tank stand pipe. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Parts
32| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 193736 | O-ring (3), Part No. 193736, has a green dot or stripe. | 1 | O ring | PartsGeek |
| 205216 | O-ring (2), Part No. 205216, has no markings. | 1 | O ring | PartsGeek |
| 3010510 | O-ring (1), Part No. 3010510, has a red dot or stripe. | 1 | O ring | PartsGeek |
| 3313279 | Full flow oil filter (Cummins Part No. 3313279) | 4 | Oil filter | Amazon eBay PartsGeek FridayParts $26.68 |
| 3313283 | Bypass oil filter (Cummins Part No. 3313283) | 2 | Oil filter | PartsGeek |
| 3315844 | fuel filter, Cummins Part No. 256837 or Fleetguard® AF-251 | 1 | Fuel filter | PartsGeek FridayParts $16.66 |
| 3315847 | fuel filter, Cummins Part No. 256837 or Fleetguard® AF-251 | 1 | Fuel filter | PartsGeek |
| 3375049 | Oil Filter Wrench | 1 | Oil filter | PartsGeek |
| 3376000 | Injector puller | 1 | Injector puller | PartsGeek |
| 3376497 | Injector puller | 1 | Injector puller | PartsGeek |
| 3377193 | Battery Tester | 1 | Battery tester | PartsGeek |
| 3379056 | Air Equipment Manual, Twin Cylinder, Bulletin No. 3379056. | Manual | PartsGeek | |
| 3379071 | PTD injectors rebuild manual | Manual | PartsGeek | |
| 3810235 | Exhaust Gas Turbocharger, RR-153, Instructions for Operation and Maintenance or Bulletin No. 3810235. | Manual | PartsGeek | |
| 3810242 | Air Equipment Manual, Single Cylinder, Bulletin No. 3810242. | Manual | PartsGeek | |
| 3810257 | unloader valve cap spring | Air filter | PartsGeek | |
| 3810313 | PT (Type D) STC injector shop manual | Manual | PartsGeek | |
| 3810325 | Exhaust-Gas Turbocharger, RR-151-12, Instructions for Operation and Maintenance or Bulletin No. 3810325. | Manual | PartsGeek | |
| 3810347 | unloader valve cap spring | Air filter | PartsGeek | |
| 3822574 | Rocker lever actuator | 1 | Actuator | PartsGeek |
| 3822575 | Injector and valve adjustment kit | 1 | Injector | PartsGeek FridayParts $96.36 |
| 3823875 | Belt tension gauge | Belt | PartsGeek | |
| FF105 | fuel filter, Fleetguard® Part No. AF-251 | 1 | Fuel filter | Amazon eBay $5.99 PartsGeek |
| FF105D | fuel filter, Fleetguard® Part No. AF-251 | 1 | Fuel filter | Amazon eBay $14.50 PartsGeek |
| KTA38-0201 | Engine Control Module | 1 | ECM / ECU | PartsGeek |
| KTA38-0202 | Engine Control Unit | 1 | ECM / ECU | PartsGeek |
| 33754364 | crack detection developer | Service part / kit | PartsGeek | |
| 3376592 | Inch Pound Torque Wrench | 1 | Service part / kit | PartsGeek |
| 3810304 | K38 and K50 Shop Manual | 1 | Service part / kit | PartsGeek |
| 3810432 | K38 and K50 Troubleshooting & Repair Manual | 1 | Service part / kit | PartsGeek |
| 3822648/3823348 | Top Stop Tappet Setting Tool (STC equipped engines only) | 1 | Service part / kit | PartsGeek |
| KTA38-0203 | Engine Control System | 1 | Service part / kit | PartsGeek |
Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.
Fuel consumption
| Rating | Load | L/h | gal/h |
|---|---|---|---|
| Prime | |||
| Standby |
Available documents
Engine spec — 0042660 (Cummins/Onan)Engine spec — 0043063 (Cummins/Onan)Spec sheet — K38-CP complete (Cummins/Onan)Reference — B20BiodieselFAQJan2009Reference — Schedule Technical2012 (Cummins/Onan)Service manual — Cummins Diesel K38-50 Manual 1993 (Cummins/Onan)Service manual — Cummins Diesel K38-50 Manual 1993 (2) (Cummins/Onan)