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Cummins/Onan K38 and K50 Engine

Name: Cummins/Onan K38 and K50 Engine
Brand: Cummins/Onan

The Cummins/Onan K38 and K50 is an engine. It powers generator sets from Cummins/Onan, including the K38 and K50.

Also known as: Cummins Engine Company, Inc. K38 and K50

Part of the Cummins/Onan K38 engine family — 2 variants share parts & fitment.

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Procedures

Engine specifications

Generator sets powered by this engine

Cummins/Onan K38 Cummins/Onan K50

How to read your Cummins/Onan engine serial & model number →

Common problems

White Smoke or Rough Running At Idle (After Warmup Period)
Cause: Low Coolant Temperature
Fix: Refer to Coolant Temperature Below Normal chart. Verify by operating engine from a temporary tank that contains good fuel.
Throttle Linkage Adjustment Wrong
Fix: Check throttle linkage adjustment for full opening of throttle lever.
Tachometer Has a Malfunction
Fix: Check with hand or digital tachometer.
Radiator Shutters are not Opening Completely or Cold Weather
Cause: Radiator Cover Closed
Fix: Open yadiator cover
Lubricating Oil Pressure Low
Cause: Incorrect Oil Level, Incorrect Oil Specifications: Oil Diluted With Fuel, Oil Temperature Above Normal (120°C [250°F))
Fix: 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
Lubricating Oil Level Too High
Fix: Check dipstick calibration and oil pan capacity. Refer to Section A.
Intake or Exhaust System Restricted
Fix: Check intake and exhaust systems for restrictions.
Fuel Suction Line Restricted
Fix: Check fuel inlet for restriction.
Fuel Suction Line or Fuel Filter Restricted
Fix: Check fuel line for restriction. Replace fuel filter if necessary.
Fuel is Spongy Throttle is Stuck
Fix: Check for air in fuel, tighten fuel connections and filter, check fuel tank stand pipe.
Fuel Filter Plugged or Fuel Waxing Due to Cold Weather
Fix: Replace fuel filter. Weather conditions can require fuel heater.
Fuel Contaminated
Fix: Verify by operating engine from a temporary supply tank.
Exhaust Smoke Excessive Under Load
Cause: Intake Air System Restricted
Fix: Check intake air system for restrictions.
Engine Will Not Shut Off
Cause: 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
Fix: 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
Engine Will Not Reach Rated Speed When Loaded
Cause: Excessive Load for Engine Horsepower Rating
Fix: Reduce load.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan K38 and K50.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			3375049	6000 hr	Amazon eBay
Fuel filter			3810432	250 hr	Amazon eBay
Oil filter			3375049	250 hr	Amazon eBay
Battery			—	6000 hr
Belt	Install the fan belt idler assembly, the three lock washers and capscrews.		—	6000 hr
Coolant		6.8 L	—	1500 hr
Coolant filter			3822648/3823348	6000 hr	buy
Oil		45.0 L	—	6000 hr
Spark plug			—	6000 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Air cleaner element - restriction	Check	250 hr	6 mo	Replace air cleaner element as required
Air compressor air cleaner element	Replace	250 hr	6 mo	Cummins two-cylinder compressor
All belts	Check	250 hr	6 mo
Belt tension	Check	250 hr	6 mo	Measure in center span of pulleys; fan idler pulley design self-tensions
Belts	Check	250 hr	6 mo	Replace cracked or frayed belts
Coolant filter	Change	250 hr	6 mo	At each oil and filter change interval
Cooling fan	Check	250 hr	6 mo	Check for cracks, loose rivets, bent or loose blades
Cooling system additives (DCA4)	Check	250 hr	6 mo	Check concentration whenever coolant is added between filter changes
Crankcase breather tube/hose	Check	250 hr	6 mo	Remove and check internally for obstructions or sludge; clean or replace
Engine oil	Change	250 hr	6 mo	Whichever occurs first
Engine oil and oil filters	Change	250 hr	6 mo	Whichever occurs first
Fan idler pivot arm	Lubricate	1500 hr	12 mo	Water pump type grease until grease appears
Fuel filter	Replace	250 hr	6 mo	Clean area around fuel filter head first
Hoses	Inspect	1500 hr	12 mo	Check/replace as required
Lubricating oil	Test	250 hr	6 mo	First service — For high horsepower engines with Eliminator™ oil filter option: take oil samples every 250 hours and analyze per Cummins Engine Oil Recommendations Bulletin 3810340; repeat for at least three oil change intervals.
Oil filters	Change	250 hr	6 mo	Change filters with oil
Pulley tensioner	Check	250 hr	6 mo
Batteries	Check	1500 hr	12 mo	Check electrolyte level and state of charge
Cold start aids	Check	1500 hr	12 mo	Seasonal
Crankshaft end clearance	Inspect	1500 hr	12 mo	Measure with dial indicator
Engine (steam clean)	Clean	1500 hr	12 mo	Before conducting any 1500 hour maintenance
Engine mounting bolts and nuts	Check	1500 hr	12 mo	Tighten loose; inspect rubber
Engine protection system	Check	1500 hr	12 mo	Follow manufacturer's recommended procedures
Fan idler pulley tensioner	Adjust	1500 hr	12 mo	Solid control rod engines only; shock absorber engines require no adjustment
Front engine support	Lubricate	1500 hr	12 mo	Lubricate until grease appears at outside of support
Heat exchanger zinc plugs (marine only)	Check	1500 hr	12 mo	Check length of all zinc plugs; replace if 50 percent eroded
Steam clean engine	Clean	1500 hr	12 mo	Before any 1500 hour maintenance
Valves and injectors	Adjust	1500 hr	12 mo	First service — Initial adjustment; then not again before 6000 hour/2 year injector calibration
Air compressor	Inspect	6000 hr	24 mo	Discharge and intake checks
Coolant	Change	6000 hr	24 mo	Clean and flush cooling system
Cooling system	Change	6000 hr	24 mo	Clean system and change antifreeze; whichever comes first
Crankcase breather element	Replace	6000 hr	24 mo	Clean/replace
Engine protection system	Adjust	6000 hr	24 mo	Calibration required
Fan hub	Inspect	6000 hr	24 mo	End clearance and grease leakage
Fan idler pulley assembly	Replace	6000 hr	24 mo	Rebuild or replace as necessary
Fuel pump	Clean	6000 hr	24 mo	Clean and calibrate at a Cummins Authorized Repair Location
Injectors	Clean	6000 hr	24 mo	Clean and calibrate at a Cummins Authorized Repair Location
Thermostats and seals	Replace	6000 hr	24 mo	Discard worn thermostats and seals
Throttle travel/throttle air cylinder	Check	6000 hr	24 mo	Throttle lever breakover 3 to 6 mm
Turbocharger	Inspect	6000 hr	24 mo	Check blades, shaft spin, axial and radial clearance

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Crankshaft end clearance	0.13 MIN / 0.51 MAX	mm
Clearance	Crankshaft end clearance	0.13 to 0.51	mm	engine mounted in unit
Clearance	Fan hub bearing end clearance	0.03 MIN / 0.15 MAX	mm
Clearance	Fan hub bearing end clearance	0.03 to 0.15	mm
Clearance	Thermostat seal installation depth	no more than 0.51	mm	below top of cast edge
Clearance	Turbocharger BB (RR-151) and (RR-153) end clearance	0.09 MIN / 0.13 MAX	mm
Clearance	Turbocharger BB bearing radial clearance - RR-151	0.75 MAX	mm	0.030 in
Clearance	Turbocharger BB bearing radial clearance - RR-153	0.55 MAX	mm	0.021 in
Clearance	Turbocharger axial end play - HC5A	0.05 MIN / 0.13 MAX	mm
Clearance	Turbocharger axial end play - HT7100	0.06 MIN / 0.16 MAX	mm
Clearance	Turbocharger axial end play - T18A	0.10 MIN / 0.23 MAX	mm
Clearance	Turbocharger radial clearance compressor impeller - HC5A	0.15 MIN / 0.45 MAX	mm
Clearance	Turbocharger radial clearance turbine wheel - HC5A	0.20 MIN / 0.55 MAX	mm
Gap	Heat exchanger zinc plug erosion limit A	approximately 19	mm	0.75 in; new 51 mm [2 in]
Gap	Heat exchanger zinc plug erosion limit B	approximately 6.4	mm	0.25 in; new 16 mm [0.625 in]
Other	Air compressor discharge carbon deposit thickness limit	2	mm	1/16 in
Other	Air starting motor minimum air pressure	480	kPa
Other	Alternator belt tension	356	N	Burroughs tension gauge ST-1293
Other	Fan belt tension (20, 22, 24 inch fan center)	2668.9 to 2891.3	N	two pulley fan drive
Other	Fan belt tension verification (28 inch fan center)	2891.3 to 3336.2	N	two pulley fan drive
Other	HVT non-top stop injector travel adjustment	10.234	mm
Other	Maximum intake restriction, clean air filter element	380	mm H2O
Other	Maximum intake restriction, dirty air filter element	635	mm H2O
Other	Maximum vibration damper thickness - Houdaille	66.38	mm	2.574 in
Other	Maximum vibration damper thickness - Made in England Before F-82	65.91	mm	2.595 in
Other	Maximum vibration damper thickness - Made in England F-82 and After	65.66	mm	2.585 in
Other	Minimum cranking speed without starting aid	150	RPM
Other	PTD injector travel limits	7.77 to 7.87	mm
Other	PTD injector travel verification specification	7.80 MIN / 7.82 MAX	mm
Other	PTD non-top stop injector travel adjustment	7.82	mm
Other	PTD non-top stop injector travel limits	7.77 to 7.87	mm
Other	Turbocharger end play - AiResearch T18A	0.10 to 0.23	mm
Other	Turbocharger end play - HT100	0.06 to 0.16	mm
Other	Turbocharger end play - Holset HC5A	0.05 to 0.13	mm
Other	Two pulley fan drive belt tension (set)	2668.9 to 2891.3	N	600 to 650 lbf
Other	Two pulley fan drive belt tension (verify)	2891.3 to 3336.2	N	650 to 750 lbf
Other	Vibration damper maximum thickness - Houdaille	65.38	mm
Other	Vibration damper thickness variation (four readings 90 degrees apart)	must not vary more than 0.25	mm	0.010 in
Other	Vibration damper thickness variation - maximum	0.25	mm	four locations 90 degrees apart
Pressure	Coolant pressure cap minimum	50	kPa	7 psi
Pressure	Exhaust back pressure - maximum	75	mm Hg	at rated speed and load
Pressure	Exhaust back pressure maximum	75	mm Hg	3 in Hg, at rated speed and load
Pressure	Maximum allowable intake restriction - clean filter element	380	mm H2O	15 in H2O
Pressure	Maximum allowable intake restriction - dirty filter element	635	mm H2O	25 in H2O
Pressure	Maximum allowable restriction to fuel pump - clean filter	100	mm Hg	4 in Hg, at rated power
Pressure	Maximum allowable restriction to fuel pump - dirty filter	200	mm Hg	8 in Hg, at rated power
Pressure	Maximum allowable restriction to pump - clean filter	100	mm Hg	at rated power
Pressure	Maximum allowable restriction to pump - dirty filter	200	mm Hg	at rated power
Pressure	Maximum allowable return line restriction	63	mm Hg
Pressure	Maximum allowable return line restriction with check valves and/or overhead tanks	165	mm Hg	6.5 in Hg
Pressure	Oil pressure - minimum at idle RPM	138	kPa
Pressure	Oil pressure, main oil rifle - maximum at rated RPM	483	kPa	15W-40 oil at 107 C [225 F]
Pressure	Oil pressure, main oil rifle - minimum at rated RPM	310	kPa	15W-40 oil at 107 C [225 F]
Pressure	Oil pressure, main oil rifle, maximum at rated RPM	483	kPa	15W-40 oil at 107 C [225 F]
Pressure	Oil pressure, main oil rifle, minimum at idle RPM	138	kPa	15W-40 oil at 107 C [225 F]
Pressure	Oil pressure, main oil rifle, minimum at rated RPM	310	kPa	15W-40 oil at 107 C [225 F]
Pressure	Throttle air cylinder leak test pressure	689	kPa	no leakage allowed
Pressure	Throttle air cylinder test pressure	560	kPa	extension rod retracted
Speed	Engine speed - must not exceed	2400	RPM	any circumstances
Speed	Engine speed must not exceed	2400	RPM	under any circumstances

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Notes
Coolant	50 percent ethylene glycol / 50 percent water	Low-silicate antifreeze meeting ASTM D4985 (less than .10% silicate)		50/50 gives -34 F freeze point and 228 F boiling point; working range 40 to 60 percent antifreeze; use refractometer, not hydrometer; pre-charge 1.5 SCA units per gallon
Coolant	50/50 low-silicate antifreeze and quality water	ASTM D4985 (less than 0.10% silicate as Na2SiO5)		Must be pre-charged with supplemental coolant additives (DCA4) to 1.5 units per gallon; never below 1.2 or above 3 units per gallon. Do not use soluble oils.
Coolant	60 percent ethylene glycol / 40 percent water	Low-silicate antifreeze	-54°C to -32°C	Arctic specification coolant mixture for -32 to -54 C [-25 to -65 F]
Engine oil		Cummins Engine Oil Recommendations Bulletin 3810340		Used to analyze oil samples for high horsepower engines with Eliminator™ oil filter option.
Engine oil	SAE 15W-40	API CE or CF4		Cummins Premium Blue or equivalent; CD or CD/SF acceptable where CE/CF4 not available; sulfated ash must not exceed 1.85 mass percent
Engine oil	SAE 5W-30 synthetic CE/SF	API CE or CF4	below -23°C	For ambient temperatures consistently below -23 C [-10 F] with no provision to keep engine warm
Fuel	ASTM No. 2 diesel	No. 2 D; blends of No. 2 D and No. 1 D below 0 C [32 F]		Viscosity must be kept above 1.3 cSt; maximum cloud and pour points 6 C [10 F] lower than ambient
Fuel	B100 biodiesel	ASTM D6751		Must conform prior to blending; revised to include a cold soak test; stability requirement still in effect.
Fuel	B20 biodiesel blend	ASTM D7467		Applies to biodiesel blends B6–B20; includes oxidation stability requirement; replaces Cummins' previous EMA B20 specification requirement. Must be purchased from a BQ9000 Certified Marketer; B100 must be sourced from a BQ9000 Accredited Producer.
Fuel	B5 biodiesel			All Cummins automotive and industrial engines are compatible with B5 biodiesel.
Fuel	biodiesel (Europe)	EN 14214		Published by CEN, European Committee for Standardization. Equivalent biodiesel specifications required internationally.
Grease	Water pump type grease (Amoco Rykon Premium No. 2 / Chevron SRI / Exxon Unirex N2 / Shell Dolium R / Texaco Premium RB)			Fan idler pivot arm and front engine support lubrication

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Alternator Belt Adjustment adjustment

⚠ Over-tensioning of alternator belts can result in premature accessory drive bushing wear and seal leakage.

Tools: GT-1293 Burroughs Tension Gauge

Loosen the alternator and adjusting link mounting capscrews.
Loosen the jam nuts on the adjusting screw.
Turn the adjusting screw clockwise to tighten the belt tension.
Check the belt tension with a gauge.
Tighten the jam nuts on the adjusting screw to 55 Nm [40 ft-lb].
Tighten the adjusting link and alternator mounting capscrews to 55 Nm [40 ft-lb].
Check the belt tension again.

Crossheads - Adjustment adjustment

Tools: ST-669 Torque Wrench Adapter

Adjust the crossheads on the cylinder that has both valves closed.
Loosen the crosshead adjusting screw locknuts on the intake and exhaust valve crossheads.
Turn the adjusting screw out at least one turn.
Hold the crosshead down against its guide.
Turn the adjusting screw in until it touches the top of the valve stem but does not raise the crosshead.
Hold the adjusting screw and tighten the lock nut to the torque value.

Dipstick Calibration adjustment

⚠ The dipstick will break if the scribe mark is too deep.

Tools: scribe

Drain the oil from the pan.
Install the dipstick in the dipstick tube.
Use clean 15W-40 oil to fill the oil pan to the specified low level.
Remove the dipstick and scribe a mark across the dipstick at the oil level. Mark the low level with an L.
Install the dipstick and add additional oil to the specified full level.
Remove the dipstick and scribe a mark across the dipstick at the oil level. Mark the high oil level with an H.

PT (type D) Injector - Adjustment adjustment

⚠ The injector plunger is under spring tension. Do NOT allow the tool to slip.

Tools: 3822575 adjustment kit, 3822574 rocker lever actuator, ST-669 adapter

Install injector and valve adjustment kit, Part No. 3822575.
Adjust indicator tip to touch top of injector plunger.
Lower indicator 12.25 mm [0.5 inch] and lock support.
Depress rocker lever until injector bottoms two or three times.
Hold plunger bottomed and set indicator to ZERO.
Turn adjusting screw until indicator reads specified travel.
Tighten locknut; verify setting.

Valves - Adjustment adjustment

⚠ Use the correct chart for the engine being serviced or the parts will be damaged.

Tools: 3376592 Inch Pound Torque Wrench, ST-669 Torque Wrench Adapter, feeler gauge

Select a feeler gauge for the correct valve lash specification and insert the gauge between the rocker lever and the crosshead.
Torque wrench method: use Part No. 3376592 inch pound torque wrench and tighten the adjusting screw to 0.68 Nm [6 in-lb].
Feel method: use a screwdriver and turn the adjusting screw only until the lever touches the feeler gauge.
The adjusting screw must not turn when the locknut is tightened.
Tighten the locknut to the value indicated.
The feeler gauge must slide backward and forward with only a slight drag.
Attempt to insert a feeler gauge 0.03 mm [0.001 in] thicker; the lash is not correct when the thicker gauge will fit.
Repeat until clearance is correct on both intake and exhaust valves.

Valves and Injectors - General Checking and Adjustment adjustment

⚠ Use the correct chart for the engine or the parts will be damaged.

⚠ Crosshead adjustment must always be made before adjusting the valves.

Tools: 3376592 inch pound torque wrench, 3822575 injector and valve adjustment kit, 3822574 rocker lever actuator, ST-669 torque wrench adapter

Steam clean engine before removing rocker lever covers.
Remove rocker lever covers and related components.
Align valve set (VS) mark on damper or flywheel with pointer.
Determine cylinder in position; crossheads and valves ready when all valves closed.
Adjust crossheads before adjusting valves.
Adjust valves to lash specification with feeler gauge.
Adjust injectors per PT (type D) or STC/HVT method.
Tighten locknuts and reinstall rocker lever covers.

Air Cleaner Element Replacement - Single Heavy Duty Dry-Type maintenance

⚠ Holes, loose end seals, dented sealing surfaces and other damage require immediate element replacement.

⚠ Pull the cover and element straight out to avoid damage.

Wipe dirt from the cover and upper portion of the air cleaner before disassembly.
Loosen the wing bolt and band clamp securing the dust pan.
Loosen the wing nut and remove the dust shield from the dust pan. Clean the dust pan and shield.
Remove the wing nut securing the primary element and inspect the rubber sealing washer.
Remove the dirty cleaner element and install the new primary element.
Make sure the rubber sealing washer is in place under the wing nut before tightening.
Assemble the dust shield and dust pan and secure with the band clamp.

Coolant Filter Replacement maintenance

⚠ Do NOT remove the radiator cap from a hot engine.

⚠ Do not allow oil to get in the filter; it will adversely affect the DCA.

Remove the coolant system pressure cap and close the shutoff valve(s), if equipped, before removing the coolant filter.
Push in the knob on the filter head or close the gate valve.
Lubricate the seal on the new filter with engine oil.
Install the new coolant filter. Turn the filter until the seal touches the filter head.
Turn the filter an additional 1/2 to 3/4 of a turn after contact.
Pull the knob on the filter head out or open the gate valve.

Cooling System - Cleaning System and Changing Antifreeze maintenance

⚠ Do not use caustic cleaners; aluminum components will be damaged.

⚠ Wait until temperature is below 50 C [120 F] before removing the pressure cap.

Drain the cooling system; do not allow it to dry out.
Add Fleetguard RESTORE or RESTORE PLUS (1 U.S. gallon per 38-57 liters capacity).
Fill system with plain water.
Operate engine at normal temperature (at least 85 C [185 F]) for 1 to 1.5 hours.
Shut off and drain the system.
Fill with clean water and operate at high idle 5 minutes above 85 C.
Shut off and drain; repeat flush if water is still dirty.
Refill with new heavy duty coolant and SCA.

Cooling System Cleaning and Changing Antifreeze maintenance

⚠ Do not use caustic cleaners in the cooling system. Aluminum components will be damaged.

⚠ Wait until the temperature is below 50 C [120 F] before removing the coolant system pressure cap.

Drain the cooling system. Do not allow the cooling system to dry out. Do not remove the coolant filter.
Add 3.8 liters [1 U.S. gallon] of Fleetguard RESTORE (or equivalent) for each 38 to 57 liters [10 to 15 gallons] of cooling system capacity and fill with plain water.
Turn the heater temperature switch to high to allow maximum coolant flow.
Operate the engine at normal operating temperatures (at least 85 C [185 F]) for 1 to 1 1/2 hours.
Shut the engine off and drain the cooling system.
Fill with clean water to flush and operate at high idle for 5 minutes above 85 C [185 F].
Shut the engine off and drain. Repeat flushing if the water is still dirty.
Refill the system with new heavy duty coolant and SCA.

Fan Belt - Removal and Installation (Back Side Idler System) maintenance

⚠ The fan belt idler is under tension. Do NOT allow your hands between the idler and belt or fan hub.

Tools: 8-point socket, breaker bar

Remove the back side idler end of the shock absorber, control rod, or turnbuckle.
Loosen upper capscrew and remove lower capscrew.
Relieve idler spring tension with an 8-point socket and breaker bar.
Remove the fan belt.
Install the belt on crankshaft and fan hub pulley, aligning grooves with pulley ribs.
Rotate idler against spring and install lock washer and capscrew; torque 45 Nm.
Install control rod or shock absorber and tighten capscrews to 60-90 Nm.

Fan Hub Inspection maintenance

Tools: dial indicator

Remove the fan belt.
Rotate the fan hub pulley to check for rough or damaged bearings.
Inspect the pulley grooves for excessive wear.
Check for grease leakage.
Use a dial indicator to check the bearing end clearance.
Replace with a new or rebuilt unit as necessary.
Install the fan belt.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Cummins/Onan K38 family

Part #	Description	Category
3810257	unloader valve cap spring	air_filter
3810347	unloader valve cap spring	air_filter
3377193	Battery Tester	battery_tester
3823875	Belt tension gauge	belt
3305373	Cummins Part No. DCA4 Units	coolant_filter
3315116	Cummins Part No. DCA4 Units	coolant_filter
3315459	Cummins Part No. DCA4 Units	coolant_filter
3317428	Cummins Part No. DCA4 Units	coolant_filter
KTA38-0201	Engine Control Module	ecm
KTA38-0202	Engine Control Unit	ecm
3315844	fuel filter, Cummins Part No. 256837 or Fleetguard® AF-251	fuel_filter
3315847	fuel filter, Cummins Part No. 256837 or Fleetguard® AF-251	fuel_filter
FF105	fuel filter, Fleetguard® Part No. AF-251	fuel_filter
FF105D	fuel filter, Fleetguard® Part No. AF-251	fuel_filter
3318319	Cummins Part No. DCA4 Units	hose
3822575	Injector and valve adjustment kit	injector
3376000	Injector puller	injector_puller
3376497	Injector puller	injector_puller
3379056	Air Equipment Manual, Twin Cylinder, Bulletin No. 3379056.	manual
3379071	PTD injectors rebuild manual	manual
3810235	Exhaust Gas Turbocharger, RR-153, Instructions for Operation and Maintenance or Bulletin No. 3810235.	manual
3810242	Air Equipment Manual, Single Cylinder, Bulletin No. 3810242.	manual
3810313	PT (Type D) STC injector shop manual	manual
3810325	Exhaust-Gas Turbocharger, RR-151-12, Instructions for Operation and Maintenance or Bulletin No. 3810325.	manual
193736	O-ring (3), Part No. 193736, has a green dot or stripe.	o_ring
205216	O-ring (2), Part No. 205216, has no markings.	o_ring
3010510	O-ring (1), Part No. 3010510, has a red dot or stripe.	o_ring
3313279	Full flow oil filter (Cummins Part No. 3313279)	oil_filter
3313283	Bypass oil filter (Cummins Part No. 3313283)	oil_filter
3313287	Full flow oil filter (Cummins Part No. 3313287)	oil_filter
3375049	Oil Filter Wrench	oil_filter
3315115	Cummins Part No. DCA4 Units	other_service
3316053	Cummins Part No. DCA4 Units	other_service
3318157	Cummins Part No. DCA4 Units	other_service
3318201	Battery Cable Group	other_service
3318318	Cummins Part No. DCA4 Units	other_service
33754364	crack detection developer	other_service
3376592	Inch Pound Torque Wrench	other_service
3810304	K38 and K50 Shop Manual	other_service
3810432	K38 and K50 Troubleshooting & Repair Manual	other_service
3822574	Rocker lever actuator	other_service
3822648/3823348	Top Stop Tappet Setting Tool (STC equipped engines only)	other_service
KTA38-0203	Engine Control System	other_service

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

Which generators use the Cummins/Onan K38 and K50 engine?

The Cummins/Onan K38 and K50 powers 2 generator set(s), including Cummins/Onan K38, Cummins/Onan K50.

How often should you change the oil in the Cummins/Onan K38 and K50?

The Cummins/Onan K38 and K50 oil change interval is every 6000 hours.

What is a common problem with the Cummins/Onan K38 and K50 engine?

A commonly reported issue on generators using the Cummins/Onan K38 and K50 is: White Smoke or Rough Running At Idle (After Warmup Period). Cause: Low Coolant Temperature. Fix: Refer to Coolant Temperature Below Normal chart. Verify by operating engine from a temporary tank that contains good fuel..