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John Deere 6068TFM Engine

The John Deere 6068TFM is a 6.8 L turbocharged engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the MDDC. It holds 19.4 L (5.1 gal) of oil and 30 L (7.9 gal) of coolant.

Also known as: John Deere 6068TFM

Part of the John Deere 6068 engine family — 92 variants share parts & fitment.

6.8 L

Displacement

1800 rpm

Rated speed

19.4 L

Oil capacity

On this pageSpecs Generator sets FAQ Service intervals Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Oil capacity	19.4 L
Coolant capacity	30.0 L
Displacement	6.8 L
Aspiration	turbocharged
Rated speed	1800 rpm

Generator sets powered by this engine

Cummins/Onan MDDC

How to read your John Deere engine serial & model number →

Common problems

Engine Coolant Temperature, Above Normal SPN: 110, FMI: 0
Water In Fuel Indicator, Above Normal SPN: 97, FMI: 0
Fuel Temperature, Volt. Out/Range SPN: 174, FMI: 3
Fuel Injection Pump Valve, Cur. Out/Range SPN: 1076, FMI: 5
Engine Oil Pressure, Below Normal SPN: 100, FMI: 1
Engine Coolant Temperature, Volt. Out/Range SPN: 110, FMI: 3
Service Check 3
Fuel Injection Pump Valve, Above Normal SPN: 1076, FMI: 0
Cause: Closure too long
Fix: See an authorized Cummins Onan service representative
Engine Speed, Above Normal SPN: 190, FMI: 0
Unknown Shutdown 36
Starting Fault 32
Speed Sense Lost 45
Overprime 57
Overcrank 4
Oil Level High or Low 6

Compiled from service & troubleshooting documentation across every generator set that uses the John Deere 6068TFM.

Service intervals

Item	Action	Hours	Months	Notes
Engine Oil Level	Check	8 hr		Before first start of day and after every 8 hours of operation
Exhaust system	Inspect	8 hr		Inspect for exhaust leaks at every startup and after every eight hours of operation
General Inspection	Inspect	8 hr		Before first start of day and after every 8 hours of operation; includes oil level, coolant level, fuel system, exhaust system, batteries
General Inspection (Oil Level, Coolant Level, Fuel System, Exhaust System, Battery, Sea Water Strainer)	Check	8 hr		Every day, all models (MDKBH, MDKBJ, MDKBW, MDKB & MDKD, MDDCX)
Battery	Check	100 hr	1 mo	Monthly, 100 Hrs, all models; see battery manufacturer recommendations
Brushes & Slip Rings	Check	200 hr		Yearly, 200 Hrs (MDKBH, MDKBJ, MDKBW only); must be performed by trained mechanic; not applicable to other listed models (—)
Oil and Filter	Change	350 hr		First service — Change oil and filter after first 50 hours, then at scheduled intervals
Serpentine Belt and Tensioner	Inspect	350 hr		Check for slippage, cracking, and wear
Pump Impeller	Replace	500 hr		Yearly, 500 Hrs, all models
Air Filter	Check	700 hr		Yearly, 700 Hrs (MDDCX only)
Air Filter	Inspect	700 hr		Clean and oil if restriction is greater than 25 inches (635 mm) WC
CCV Filter	Replace	700 hr		Shut down engine for 2 minutes every 24 hours to allow auto drainage of crankcase oil
Fuel Filters	Change	700 hr
Zinc Anode	Inspect	700 hr
Raw Water Pump Impeller	Replace	1050 hr		Replace every 1050 hours
Generator Bearing(s) & Drive Belt	Change	2000 hr	60 mo	5 Yrs, 2000 Hrs, all models; must be performed by a trained and experienced mechanic
Fuel Injectors	Replace	2100 hr		Must be performed by a qualified mechanic (authorized Cummins Onan Dealer)
Valve Lash	Adjust	2100 hr		Must be performed by a qualified mechanic (authorized Cummins Onan Dealer)
Battery and Battery Connections	Check		1 mo	See battery manufacturer's recommendations
Coolant, Pressure Cap & Thermostat	Change		24 mo	2 Yrs, all models
Coolant, Pressure Cap, and Thermostat	Replace		24 mo	Replace every 2 years
Generator Bearing	Inspect		60 mo	Replace every 5 years; must be performed by a qualified mechanic
Oil / Oil Filter	Change			First service — First 50 Hrs - Yearly, 200 Hrs (MDKBH, MDKBJ, MDKBW, MDKB & MDKD Models K,L,M,N,P,R,V); First 50 Hrs - Yearly, 350 Hrs (MDKB & MDKD Models S,T,U; MDDCX)

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	Clearance - air inlet and outlet openings	127	mm	5 inches
Clearance	Clearance - engine end (serpentine belt replacement)	305	mm	12 inches
Clearance	Clearance - non-service sides	50	mm	2 inches
Clearance	Exhaust piping clearance from combustible construction	229	mm	9 inches
Clearance	Siphon break above highest marked water line (min)	152	mm	6 inches
Other	10% Overload Engine Power	107 hp (80 kW)
Other	10% Overload Engine Power	131 hp (98 kW)		50 Hz
Other	10% Overload Engine Power	162 hp (121 kW)
Other	10% Overload Engine Power	82 hp (61 kW)		50 Hz
Other	Battery Charging Output - Iso Gnd	12V - 70 Amps / 24V - 45 Amps
Other	Battery Charging Output - Neg Gnd	12V - 60 Amps / 24V - 40 Amps
Other	Compression Ratio	17.0 : 1		6-cylinder
Other	Compression Ratio	17.6 : 1		4-cylinder
Other	Coolant Flow Rate	14 gal/min (53 L/min)		50 Hz
Other	Coolant Flow Rate	25 gal/min (94 L/min)
Other	Coolant Flow Rate	31 gal/min (116 L/min)		50 Hz
Other	Coolant Flow Rate	33 gal/min (125 L/min)
Other	Coolant flow rate	53	L/min	50 Hz ratings
Other	Coolant flow rate	94	L/min	60 Hz ratings
Other	Coolant flow rate (50 Hz ratings)	53	L/min	50 Hz ratings
Other	Coolant flow rate (60 Hz ratings)	94	L/min	60 Hz ratings
Other	Displacement	275 in3 (4.5 L)		4-cylinder
Other	Displacement	415 in3 (6.8 L)		6-cylinder
Other	Exhaust Gas Flow	463 ft3/min (13.1 m3/min)
Other	Exhaust Gas Flow	848 ft3/min (24 m3/min)
Other	Exhaust hose/pipe slope (min, without sagging)	1/2 inch per foot (42 mm/meter)
Other	Frequency Regulation	Isochronous
Other	Fuel Supply and Return Connection Size	1/4 - 18 NPTF
Other	Heat Rejection to Coolant	2681 Btu/min (47 kW)		50 Hz
Other	Heat Rejection to Coolant	3523 Btu/min (62 kW)
Other	Heat Rejection to Coolant	4554 Btu/min (80 kW)		50 Hz
Other	Heat Rejection to Coolant	5863 Btu/min (103 kW)
Other	Lube Oil Drain Connection	3/8 inch NPT
Other	Max fuel lift	3	m
Other	Maximum Angularity, any direction	30	Degrees
Other	Maximum Fuel Height above Inj. Pump	10	ft
Other	Maximum Leak-off Return Height	8	ft
Other	Maximum Pump Suction Lift	10	ft
Other	Minimum Required Fuel Line ID	0.25	inch
Other	Raw Water Inlet Connection Size (OD)	1.25	in
Other	Recommended Battery Capacity @ 32 F (0 C)	12V - 640 CCA / 24V - 570 CCA
Other	Recommended Battery Capacity @ 32 F (0 C)	12V - 800 CCA / 24V - 570 CCA
Other	Sea Water Pump Flow	18 gal/min (70 L/min)		50 Hz
Other	Sea Water Pump Flow	22 gal/min (84 L/min)
Other	Starter Rolling Current @ 32 F (0 C)	12V - 780 Amps / 24V - 600 Amps
Other	Starter Rolling Current @ 32 F (0 C)	12V - 920 Amps / 24V - 600 Amps
Other	Total Fuel Flow	29 gal/hr (109 L/hr)
Other	Total Fuel Flow	30 gal/hr (113 L/hr)
Pressure	Engine oil pressure (low - fault SPN 100 FMI 1)	24 to 51	psi (165 to 350 kPa)	depending on engine speed
Pressure	Max. Fuel transfer suction with Auxiliary Pump	18	in Hg
Pressure	Max. Pressure Drop Across Keel Cooler	3	psi
Pressure	Max. Pressure Drop Across Keel Cooler	4	psi
Pressure	Maximum Air Intake Restriction - Clean Element	12	inches H20
Pressure	Maximum Air Intake Restriction - Dirty Element	25	inches H20
Pressure	Maximum Back Pressure	30	inches H20
Pressure	Maximum Exhaust Back Pressure	2.2	in Hg
Pressure	Maximum Fuel Return Pressure (Restriction)	3	psi
Pressure	Maximum Fuel transfer pump suction	8	in Hg
Pressure	Maximum Leak-off Line Pressure	3	psi
Pressure	Maximum Outlet Pressure	20	psi

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	Capacity	Notes
Coolant		Fleetguard - ES Compleat and EG Premix		Ethylene glycol based coolant (also known as summer coolant, coolant additive).
Coolant	50/50 mixture water/ethylene glycol (protection to -37 C); 60/40 recommended in warmer climates and sea water environments	ASTM D6210		Capacity 14 L (15 qt) for 4-cylinder models; 30 L (32 qt) for 6-cylinder models
Coolant	50/50 water/ethylene glycol		2.1 L	MDKBH; also stated as 2.2 Qt
Engine oil	15W40	Premium Blue E 15W40		Lubricant oil; used in engine lubricant oil systems, sump pan and filters.
Engine oil	SAE 15W-40 (multi-grade recommended year round); choose viscosity per ambient temperature	API CF, CF-4, CG-4, CH-4, or CI-4 (break-in: API CE, CD, or CC)		Capacity 12.6 L (13.3 qt) for 4-cylinder models; 19.4 L (20.5 qt) for 6-cylinder models
Fuel		ASTM D975		Bio-diesel meeting ASTM D6751 or EN14214, blended with ASTM D975 diesel up to B20. Bio-diesel compatible fuel water separator required.
Fuel	Grade 2-D diesel fuel (Grade 1-D where ambient below 5 C/40 F); cetane not less than 45; sulfur not more than 0.5% by weight	EN 590 or ASTM D975; lubricity per ASTM D6078 (min 3100 g) or ASTM D6079/ISO 12156-1 (max scar 0.45 mm)		B5 bio-diesel suitable; B5-B20 per model Spec C compatibility; bio-diesel meeting ASTM D6751 or EN14214
Fuel	No. 2 Diesel	EN 590 or ASTM D975

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

Fault codes

Code	Name	Meaning	Severity	Action
1	One blink	Shutdown due to high engine temperature	Shutdown
2	Two blinks	Shutdown due to low oil pressure	Shutdown
3	Three blinks	Shutdown that may require service	Shutdown	See Troubleshooting in the Operator's Manual
4	Overcrank	Cranking time exceeded 20 to 60 seconds, depending on engine temperature	Shutdown	Disconnect PTO; check fuel level; open fuel valves; prime fuel system; service battery; remove air/exhaust blockages; replace fuel filters; check air filter; change engine oil viscosity
5	Warning Shutdown due to CO	Dangerous levels of Carbon Monoxide in vessel	Shutdown	Get everyone into fresh air immediately and seek medical attention
6	Oil Level High or Low	Engine oil level is too low or too high	Shutdown	Add or drain oil; check for leaks; contact authorized service rep if oil contains water/coolant
7	Loss of Raw Water Flow	Low raw water pressure in heat exchanger	Shutdown	Open sea cock; clean sea water strainer; check hoses; check raw water impeller; check hull through-fitting
12	High AC Voltage	Output voltage jumped to more than 125% of rated for 75 ms or more than 115% of rated for 3 seconds	Shutdown	Does not apply with PMG excitation; check/reset circuit breaker and run fewer loads; check fuel fittings/filters; prime fuel system; isolate external circuits
13	Low AC Voltage	Output voltage fell to less than 90% of rated for 5 seconds	Shutdown	Does not apply with PMG excitation; disconnect PTO and reduce loads; check fuel level; remove blockages; prime fuel system; check fuel fittings; replace fuel filters
14	High AC Frequency	Frequency jumped to more than 70 Hz for 40 ms or more than 2% over nominal for 6 seconds	Shutdown	Check/reset circuit breaker and run fewer loads; check fuel fittings and filters for leaks
15	Low AC Frequency	Frequency fell to less than 90% of nominal for more than 8 seconds	Shutdown	Disconnect PTO and reduce loads; check fuel level; remove blockages; prime fuel system; check fuel fittings; replace fuel filters; check air filter
16	Engine Fault	Engine fault; press INFO for FAULT INFO screen with SPN/FMI codes	Shutdown	See engine fault code SPN/FMI tables
27	Loss of AC Voltage Sense	Controller lost VAC sensing during normal voltage regulation	Shutdown	See an authorized Cummins Onan Service Representative
29	High Battery Voltage	Battery voltage greater than 19.2 V (12 VDC system) or 32.2 V (24 V system)	Shutdown	Check battery bank connections; select lower battery booster charge rate
32	Starting Fault	Controller could not detect cranking speed for 3 seconds	Shutdown	Disconnect PTO; have propulsion engines running; service battery; change engine oil viscosity
35	Control Card Failure - EE	Controller detected an EE memory error	Shutdown	See an authorized Cummins Onan Service Representative
36	Unknown Shutdown	Engine speed fell below 1000 RPM for 0.5 seconds	Shutdown	Check for mechanical damage; reduce loads; check fuel; prime fuel system; remove blockages; check fuel fittings; replace fuel filters; check air filter
37	Invalid Generator Set Configuration	Controller not configured properly for the generator set	Shutdown	See an authorized Cummins Onan service representative
43	Control Card Failure - RAM	Controller detected a RAM memory error	Shutdown	See an authorized Cummins Onan Service Representative
45	Speed Sense Lost	After start disconnect controller lost speed sense for 0.25 seconds	Shutdown	See an authorized Cummins Onan Service Representative
46	Generator Set Overload	Engine load exceeded 135 percent of rating for 10 seconds	Shutdown	Reduce the number of electrical and mechanical (PTO) loads
57	Overprime	A local or remote control switch was held in the prime position for more than 5 minutes	Warning	Remove any object holding a control switch in the prime position
58	High Exhaust Temperature	Exhaust temperature exceeded design limits due to lack of water to the exhaust/water mixer	Shutdown	Open sea cock; check hoses; clean sea water strainer; inspect siphon break; check raw water impeller; clean heat exchanger
59	Low Coolant Level	Engine coolant level fell below the optional coolant level sensor	Shutdown	Add coolant as necessary and repair leaks
61	External Shutdown	Generator set shut down by a fire suppression system or other external control	Shutdown	Make necessary repairs; reset the external control
72	Lost NIM Communications	Controller lost communication with the NIM for 15 seconds	Shutdown	See an authorized Cummins Onan service representative
SPN: 1, FMI: 0	Engine Fault, Above Normal	Engine controller not in communication with NIM	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 97, FMI: 0	Water In Fuel Indicator, Above Normal	Water is present in the fuel separator	Shutdown	Drain the water from the fuel separator
SPN: 97, FMI: 16	Water In Fuel Indicator, Above Normal	Water is present in the fuel separator	Warning	Drain the water from the fuel separator
SPN: 100, FMI: 1	Engine Oil Pressure, Below Normal	Engine oil pressure below 24 to 51 psi (165 to 350 kPa) depending on engine speed	Shutdown	Check engine oil level and add or drain as necessary; repair oil leaks
SPN: 100, FMI: 3	Engine Oil Pressure, Voltage Out of Range	Sensor or wiring is shorted or open	Warning	See an authorized Cummins Onan service representative
SPN: 100, FMI: 4	Engine Oil Pressure, Volt. Out/Range	Engine oil pressure sensor or wiring is open or grounded	Warning	See an authorized Cummins Onan service representative
SPN: 100, FMI: 18	Engine Oil Pressure, Below Normal	Engine oil pressure below 165 to 350 kPa (24 to 51 PSI) depending on engine speed	Warning	Check engine oil level and add or drain as necessary; repair oil leaks
SPN: 105, FMI: 3	Intake Manifold Temperature, Volt. Out/Range	Sensor or wiring is shorted or open	Warning	See an authorized Cummins Onan service representative
SPN: 105, FMI: 16	Intake Manifold Temperature, Above Normal	Intake manifold temperature is above 150 C (302 F)	Warning	See an authorized Cummins Onan service representative
SPN: 110, FMI: 0	Engine Coolant Temperature, Above Normal	Engine coolant temperature above 244 F (118 C)	Shutdown	Clean sea water strainer; check coolant level; check hoses; inspect siphon break; check raw water impeller; check hull through-fitting
SPN: 110, FMI: 3	Engine Coolant Temperature, Volt. Out/Range	Sensor or wiring is shorted or open	Warning	See an authorized Cummins Onan service representative
SPN: 110, FMI: 4	Engine Coolant Temperature, Volt. Out/Range	Sensor or wiring is shorted to ground	Warning	See an authorized Cummins Onan service representative
SPN: 110, FMI: 15	Engine Coolant Temperature, Above Normal	Engine coolant temperature above 226 F (108 C)	Warning	Clean sea water strainer; check coolant level; check hoses; inspect siphon break; check raw water impeller; check hull through-fitting
SPN: 110, FMI: 16	Engine Coolant Temperature, Above Normal	Engine coolant temperature above 235 F (113 C)	Warning	Clean sea water strainer; check coolant level; check hoses; inspect siphon break; check raw water impeller; check hull through-fitting
SPN: 158, FMI: 17	Battery Potential, Below Normal	ECU cannot power down	Warning	See an authorized Cummins Onan service representative
SPN: 174, FMI: 3	Fuel Temperature, Volt. Out/Range	Sensor or wiring shorted or open	Warning	See an authorized Cummins Onan service representative
SPN: 174, FMI: 4	Fuel Temperature, Volt. Out/Range	Sensor or wiring shorted or open	Warning	See an authorized Cummins Onan service representative
SPN: 174, FMI: 16	Fuel Temperature, Above Normal	Return fuel temperature above 248 F (120 C)	Warning	See an authorized Cummins Onan service representative
SPN: 190, FMI: 0	Engine Speed, Above Normal	Engine speed exceeded 3400 rpm	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 190, FMI: 16	Engine Speed, Above Normal	Engine speed exceeded 3000 rpm	Warning	See an authorized Cummins Onan service representative
SPN: 620, FMI: 3	5 Volts DC Supply, Volt. Out/Range	5 V supply shorted to battery voltage	Warning	See an authorized Cummins Onan service representative
SPN: 620, FMI: 4	5 Volts DC Supply, Volt. Out/Range	5 V supply shorted to ground	Warning	See an authorized Cummins Onan service representative
SPN: 629, FMI: 13	Controller #1, Out of Calib.	The engine controller requires recalibration	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 637, FMI: 2	Timing (Crank) Sensor, Data Erratic	Excessive signal noise	Warning	See an authorized Cummins Onan service representative
SPN: 637, FMI: 10	Timing (Crank) Sensor, Abnormal Rt/Chg.	Improper signal pattern	Warning	See an authorized Cummins Onan service representative
SPN: 970, FMI: 31	Auxiliary Engine Shutdown Switch	An external controller sent a shutdown signal to the engine controller	Shutdown	Investigate cause of shutdown; make necessary repairs; reset the external controller
SPN: 971, FMI: 31	Engine Derate Switch	An external derate input has been activated	Warning	See an authorized Cummins Onan service representative
SPN: 1076, FMI: 0	Fuel Injection Pump Valve, Above Normal	Closure too long	Warning	See an authorized Cummins Onan service representative
SPN: 1076, FMI: 1	Fuel Injection Pump Valve, Above Normal	Closure too short	Warning	See an authorized Cummins Onan service representative
SPN: 1076, FMI: 3	Fuel Injection Pump Valve, Volt. Out/Range	Sensor or wiring shorted or open	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 1076, FMI: 5	Fuel Injection Pump Valve, Cur. Out/Range	Fuel injection pump fuel control valve open	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 1076, FMI: 6	Fuel Injection Pump Valve, Cur. Out/Range	Fuel injection pump fuel control valve open or grounded	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 1076, FMI: 7	Fuel Injection Pump Valve, Above Normal	ECU failed to detect closure	Warning	See an authorized Cummins Onan service representative
SPN: 1076, FMI: 10	Fuel Injection Pump Valve, Abnormal Rt/Chg	Fuel injection pump fuel control valve circuit resistance	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 1076, FMI: 13	Fuel Injection Pump Valve, Out of Calib.	Fuel injection pump fuel control valve circuit resistance due to connector	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 1109, FMI: 31	Approaching Shutdown	Engine controller protection circuit approaching shutdown (30 seconds)	Warning	See an authorized Cummins Onan Service Representative
SPN: 1110, FMI: 31	Engine Has Shut Down	Engine controller protection circuit has shut down	Shutdown	See an authorized Cummins Onan Service Representative
SPN: 1569, FMI: 31	Engine Torque Derate	A derate condition exists - check coolant temperature, oil pressure, fuel temperature	Warning	See an authorized Cummins Onan Service Representative
SPN: 2000, FMI: 06	ECU Failure, Cur. Out/Range	ECU failure	Shutdown	See an authorized Cummins Onan Service Representative

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

Procedures

Adjusting AC Output Voltage (Non-PMG) Using Control Switch adjustment

Start genset, let voltage and frequency stabilize 5 to 10 seconds; disconnect all loads.
Rapidly press START 6 times during the first minute to enter voltage adjust mode; amber lamp blinks.
Press and quickly release START to raise voltage about 0.6 volts.
Press and hold START about 2 seconds to lower voltage about 0.6 volts.
Wait about 20 seconds for the amber lamp to stop blinking, then press STOP to save.
Restart the genset and check voltage.

Adjusting AC Output Voltage (Non-PMG) Using Digital Display adjustment

Tools: Separate voltmeter

Start genset, let voltage and frequency stabilize 5 to 10 seconds; disconnect all loads.
Rapidly press START 6 times during the first minute after startup to enter voltage adjust mode.
Press and quickly release START to raise voltage about 0.6 volts per press.
Press and hold START about 1 second to lower voltage about 0.6 volts per press.
Wait about 20 seconds for display to return to Running, then press STOP to save.
Restart the genset and check voltage.

Adjusting PMG Excited Generator Voltage Using Voltage Regulator Trimmer adjustment

Tools: Small flat-bladed screwdriver

If the generator set has a sound shield enclosure, remove the front access panel below the control box.
Remove the voltage regulator access cover.
Push the SINGLE (PARALLEL) operation switch up to SINGLE.
Start the generator set and let voltage and frequency stabilize; disconnect all loads.
Using a small flat-bladed screwdriver, turn the voltage trimmer clockwise to increase voltage or counterclockwise to decrease voltage.

Adjusting Quad Winding Generator Voltage Using Control Switch adjustment

Start the generator set and let voltage and frequency stabilize for 5 to 10 seconds; disconnect all loads.
Rapidly press START 6 times during the first minute after start up to enter voltage adjust mode.
To adjust voltage up, press and quickly release START (approx. 0.6 volts per press).
To adjust voltage down, press and hold START for about 1 second.
Wait about 20 seconds for the amber lamp to stop blinking, then press STOP to save.
Restart the generator set and check voltage.

Adjusting Quad Winding Generator Voltage Using Digital Display adjustment

⚠ Hazardous Voltage! Touching uninsulated live parts can result in severe personal injury or death.

Start the generator set and let voltage and frequency stabilize for 5 to 10 seconds; disconnect all loads.
Rapidly press START 6 times during the first minute after startup to enter voltage adjust mode.
To adjust voltage up, press and quickly release START (approx. 0.6 volts per press).
To adjust voltage down, press and hold START for about 1 second.
Wait about 20 seconds for status change from Volt Adj to Running, then press STOP to save.
Restart the generator set and check voltage.
Recalibrate AC voltage on the digital display as instructed in the Operator Manual.

Adjusting Reactive Droop Compensation adjustment

Check for correct droop CT connections and polarity, especially if the generator has been reconnected.
Adjust voltage in accordance with the preceding procedure.
Push the SINGLE (PARALLEL) operation switch down to PARALLEL.
Start the generator set and connect at least 1/2 rated load.
Measure voltage at the voltage regulator terminals to which the droop CT leads are connected; expect less than 5 VAC.
Multiply the reciprocal of the measured voltage by 100 to get percentage of full rotation required of the droop trimmer.
Turn the voltage droop trimmer fully counterclockwise to zero, then clockwise the approximate percentage of full rotation.

Adjusting Voltage (PMG Excited Alternators) adjustment

⚠ Hazardous voltage - touching uninsulated live parts can cause severe personal injury or death

Tools: Small flat-bladed screwdriver

If fitted with a sound shield enclosure, remove the front access panel below the control box.
Remove the voltage regulator access cover.
Push the Single/Parallel Operation Switch up to SINGLE.
Start the genset, let voltage and frequency stabilize and disconnect all loads.
Turn the Voltage Trimmer clockwise to increase or counterclockwise to decrease voltage.

Changing the Wet Exhaust Elbow Orientation adjustment

Remove the formed raw water hose.
Loosen the support bracket.
Turn the elbow in the desired direction.
Retighten the bracket screw.
Select and install the proper formed hose from among the three provided.
Discard the unused hoses.

Exhaust Water Separator Backflow Test diagnostic

⚠ Backflow can cause major engine damage if the cylinders become flooded.

Prepare by closing the drain hose sea cock and disconnecting the hose from the water separator.
Open the sea cock while keeping the hose raised to its fitting on the water separator.
Operate the boat throughout its speed range and verify there is no backflow.

Raw Water Pickup Test diagnostic

Close the sea cock and disconnect the raw water pickup hose from the generator set. Alternatively, connect a clear plastic hose to the strainer or sea cock.
Raise the end of the hose above expected water level and open the sea cock. Mark the water line on the generator set or enclosure while docked.
Operate the boat through its speed range in forward and reverse; have someone monitor and mark the highest water level.

Changing Wet Exhaust Elbow Orientation installation

Remove the formed raw water hose.
Loosen the support bracket.
Turn the elbow to point 45 degrees forward or 45 degrees rearward.
Retighten the support bracket screw.
Install the proper formed hose from among the three provided and discard the unused hoses.

Connecting Battery Cables installation

⚠ Sparks can ignite fuel leading to severe personal injury or death. Do not run battery cables and fuel lines together.

Tools: Insulated wrench

Bolt the cables to the engine starter solenoid and engine block using an insulated wrench.
Provide an insulating boot for the positive (+) terminal to protect against accidental contact.
Route battery cables through holes in the sides and bottom of the base.
Use the rubber grommets provided to protect the cables from chaffing and seal noise.
Make sure all unused hose and cable entrance/exit holes around the base are capped or sealed.

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

Voltage reconnection

Voltage	Phase	Connection	Notes
220/208	3	12 Lead Reconnectable	Applies to MDKDP (60 Hz), MDKDR (60 Hz), MDKDS
220/380	3	12 Lead Reconnectable	Applies to MDKDP, MDKDR, MDKDT, MDKDU
3-phase	3	12 Lead Reconnectable	Applies to MDDCW, MDDCU, MDDCY, MDDCS, MDDCT

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 John Deere 6068 family

300

Part #	Description	Category
100-001	Air Filter	Air filter
24-21000	Air Filter	Air filter
60205	MOUNT, CONTROL BOX - COMMON	Air filter
85400737	OUTER AIR FILTER	Air filter
85400786	INNER AIR FILTER	Air filter
85403921	AIR FILTER HEAVY DUTY	Air filter
C03327	Air Cleaner	Air filter
C03396	AIR FILTER	Air filter
G030077	Air Cleaner Element (Engine) Primary	Air filter
G030078	Air Cleaner Element (Engine) Secondary	Air filter
GM100703	Element, Primary	Air filter
GM100704	Element, Safety	Air filter
GM90735	Air Cleaner	Air filter
GM91358	Element, Air Cleaner	Air filter
GM92823	Element, Air Cleaner Safety	Air filter
GM94203	Heavy Duty Air Cleaner	Air filter
MQ-125-AIR-FILTER	Air Filter	Air filter
DZ114956	ALTERNATOR	Alternator
DZ117503	ALTERNATOR	Alternator
DZ123153	ALTERNATOR	Alternator
LSA462M3	Alternator	Alternator
RE505895	ALTERNATOR (12V, 75A)	Alternator
RE506196	Alternator 12 Volt 55 Amp	Alternator
RE533516	ALTERNATOR	Alternator
RE533653	ALTERNATOR	Alternator
RE533654	ALTERNATOR	Alternator
RE537146	ALTERNATOR (28V, 50A) (3142)	Alternator
RE537507	ALTERNATOR (12V, 90 A) (31AE)	Alternator
RE537508	ALTERNATOR	Alternator
RE550906	ALTERNATOR	Alternator
RE555751	ALTERNATOR	Alternator
RE558675	ALTERNATOR	Alternator
RE558676	ALTERNATOR	Alternator
RE558678	ALTERNATOR	Alternator
RM100224	ALTERNATOR (REMAN FOR RE505895) (12V, 75A) (3135)	Alternator
SE501341	(REMAN FOR AT161324, DZ114957) (3142)	Alternator
SE502560	(3164)	Alternator
SE502628	ALTERNATOR (REMAN FOR RE533654) (12V, 120A) (3141)	Alternator
85402451	VOLTAGE REGULATOR	Avr
8972824026	Battery Acid charge Pb-Ca maintenance free, 24V - 1100 CCA	Battery
MQ-125-BATTERY	Battery	Battery
85425460	BELT	Belt
DZ114929	FAN BELT (LGTH = 1655 mm)	Belt
DZ115455	FAN BELT (LGTH = 1550 mm)	Belt
DZ115812	FAN BELT (LGTH = 1680 mm)	Belt
DZ117267	FAN BELT (LGTH = 1690 mm)	Belt
DZ117268	FAN BELT (LGTH = 1530 mm)	Belt
DZ118556	FAN BELT	Belt
DZ118557	FAN BELT	Belt
DZ118558	FAN BELT	Belt
DZ118559	FAN BELT	Belt
DZ118560	FAN BELT	Belt
DZ118561	FAN BELT; LGTH = 1750 mm (24JX)	Belt
DZ118764	FAN BELT (LGTH = 1525 mm)	Belt
DZ118781	FAN BELT (LGTH = 1700 mm)	Belt
DZ118786	FAN BELT	Belt
DZ118815	FAN BELT (LGTH = 1725 mm)	Belt
DZ119018	FAN BELT	Belt
DZ119059	FAN BELT	Belt
DZ119060	FAN BELT (LGTH = 1555 mm)	Belt
DZ119061	FAN BELT (LGTH = 1540 mm)	Belt
DZ119062	FAN BELT	Belt
DZ119063	FAN BELT	Belt
DZ119416	FAN BELT	Belt
DZ119477	FAN BELT (LGTH = 1565 mm)	Belt
DZ119478	FAN BELT (LGTH = 1570 mm)	Belt
DZ119515	FAN BELT	Belt
DZ119516	FAN BELT	Belt
DZ119520	FAN BELT	Belt
DZ119521	FAN BELT	Belt
DZ119522	FAN BELT	Belt
DZ119530	FAN BELT (LGTH = 1675 mm)	Belt
DZ119531	FAN BELT	Belt
DZ119533	FAN BELT	Belt
DZ119715	FAN BELT	Belt
DZ121128	FAN BELT; LGTH = 1725 mm (24JW)	Belt
DZ121129	FAN BELT	Belt
DZ121133	FAN BELT	Belt
GM70424-1	Fan Belt (12V)	Belt
GM70424-2	Fan Belt (24V)	Belt
GM70798-1	Fan Belt	Belt
GM70798-2	Fan Belt	Belt
GM70798-3	Fan Belt	Belt
GM70798-4	Fan Belt	Belt
GM84749	Fan Belt	Belt
L114292	FAN BELT	Belt
MQ-125-BELT	V-Belt	Belt
R123308	Drive Belt, L1066H Late Production and M1066H all	Belt
R123437	Drive Belt, LP-MP668T-H (with turbo)	Belt
R123439	Drive Belt, LP-MP445D (non-turbo)	Belt
R123457	Drive Belt LP-MP668T-H (with turbo, formerly #R123464)	Belt
R123464	Drive Belt, LP668D (non-turbo, replaces R123463)	Belt
R134625	FAN BELT (LGTH = 1645 mm)	Belt
R500277	FAN BELT	Belt
RE518097	Belt Tensioner	Belt
T282795	FAN BELT	Belt
T428692	FAN BELT (LGTH = 1665 mm)	Belt
T428724	FAN BELT (LGTH = 1575 mm)	Belt
T428725	FAN BELT	Belt
T428818	FAN BELT	Belt
T428820	FAN BELT (LGTH = 1580 mm)	Belt
T428822	FAN BELT	Belt
T428823	FAN BELT	Belt
T428825	FAN BELT	Belt
T428863	FAN BELT	Belt
VP64S17	Pump Belt	Belt
011064	Cold Weather Operation	Cold weather operation
RM100100	CONTROLLER	Controller
RM100131	CONTROLLER	Controller
SE502800	CONTROLLER	Controller
SE502801	CONTROLLER (REMAN FOR RE520953) (8498) (8420) (8414)	Controller
362140-S	Main controller circuit board	Controller board
950-1682	Coolant filter	Coolant filter
MOOOOO-20001Q	Auto START/STOP Engine Controller (ECU)	ECM / ECU
RE522680	Short Block Assembly (L-M1066H and NL1066H4)	Engine
5990101	Power switching device (contactor)	Exerciser switch
950-1683	Pilot Hydraulic Filter	Filter
950-2002	Secondary Fuel Filter	Filter
MQ-125-FUEL-FILTER	Fuel Filter	Filter
MQ-125-OIL-FILTER	Oil Filter	Filter
85403756	BATTERY ELECTROLYTE	Fluid
G122208	Clarke Eng Fluid - 5 gal	Fluid
G122209	Clarke Eng Fluid -1 gal	Fluid
MQ-125-COOLANT	Coolant	Fluid
MQ-125-OIL	Engine Oil	Fluid
TY22041	John Deere ENGINE BREAK-IN OIL (SAE 10W-30)	Fluid
24-51003	Fuel Filter without Drain Valve	Fuel filter
24-51005	Fuel Filter with Metal Drain Valve	Fuel filter
85400976	FUEL FILTER	Fuel filter
85403525	FUEL FILTER SEPARATOR	Fuel filter
85431120	FUEL FILTER	Fuel filter
950-2001	Fuel Filter	Fuel filter
CO2775	Element, Fuel Water Separator	Fuel filter
CO2776	Element, Fuel Filter Primary	Fuel filter
DZ112918	SECONDARY FUEL FILTER	Fuel filter
DZ115392	Secondary Fuel Filter	Fuel filter
DZ122688	SECONDARY FILTER ELEMENT (35E6)	Fuel filter
DZ128543	PRIMARY FUEL FILTER	Fuel filter
GM50006	Fuel Filter	Fuel filter
GM50074	Fuel Filter (primary)	Fuel filter
P-205-003	Fuel Filter	Fuel filter
RE509031	Filter Element	Fuel filter
RE5090362	Fuel filter	Fuel filter
RE509208	Filter Element (also order R113565)	Fuel filter
RE520906	PRIMARY FUEL FILTER	Fuel filter
RE522878	Fuel filter	Fuel filter
RE541578	CRANKSHAFT PULLEY AND DAMPER; OD = 190 mm (1343)	Fuel filter
RE541922	PRIMARY FUEL FILTER	Fuel filter
RE60021	FINAL FUEL FILTER	Fuel filter
RE62419	FUEL FILTER	Fuel filter
SE501934	(16CB)	Fuel injection nozzle
11-11013	Gasket, Thermostat Cover Mounting	Gasket
11-11023	Gasket, Manifold to Expansion Tank	Gasket
11-11043	Gasket	Gasket
11-21011	Gasket	Gasket
11-31031	Gasket, Turbo Oil Return	Gasket
11-31615	Gasket	Gasket
11-31635	Gasket, Turbo Exhaust (K27)	Gasket
33702	GASKET KIT	Gasket
36476	GASKET KIT	Gasket
85401131	ROCKER COVER GASKET	Gasket
DZ123559	COMPLETE BLOCK ASSEMBLY INCLUDES CYLINDER HEAD WITH VALVES AND ROCKER ARM ASSEMBLY, COMPLETE GASKET KIT WITH FRONT AND REAR SEALS	Gasket
R116516	Engine Cylinder Head Gasket	Gasket
R123226	Gasket, Water By-pass Tube	Gasket
R123345	Gasket, Thermostat Housing	Gasket
R123354	Gasket, Engine Oil Pan	Gasket
R123417	Gasket, Water Pump	Gasket
R123501	Gasket	Gasket
R123504	Gasket, Remote Oil Filter Adapter	Gasket
R123525	Gasket	Gasket
R123543	Gasket, Rocker Arm Cover	Gasket
R123570	Gasket	Gasket
R123572	Gasket	Gasket
R135896	Gasket	Gasket
R500374	Gasket	Gasket
R504882	Gasket, Rocker Arm Cover Mounting	Gasket
R53108	Gasket, Starting Motor	Gasket
R90658	Gasket, Exhaust Manifold	Gasket
10000037182	Clamp, hose - spring type CTB-27ST	Hose
18-19501	Hose 1-1/4" ID x 3-1/2" 3 Ply Silicone	Hose
18-21016	Hose, 2" I.D. x 1-3/4" 3 Ply Silicone	Hose
18-31605	Hose, 1-1/4 x 32" Wire Reinforced	Hose
50332	Hose, fuel .750 ID 35 PSI SAE 30R7	Hose
60316	Clamp, hose - SAE 032 (1.56-2.50)	Hose
85401289	RADIATOR TOP HOSE	Hose
85426005	RADIATOR BOTTOM HOSE	Hose
GM62396	Hose, Reducer	Hose
GM91647	Hose, Hump	Hose
R128455	Hose, Radiator Inlet	Hose
R128456	Hose, Radiator Outlet	Hose
25-11011	Impeller with Gasket	Impeller
25-15704	Impeller	Impeller
35104	NOZZLE CLAMP ASSEMBLY	Injector
85400893	INJECTOR	Injector
RE48786	Fuel Injector (with turbocharger, includes keys 2-3)	Injector
RE519730	Fuel Injector	Injector
RE60062	Fuel Injector (without turbocharger, includes keys 2-3)	Injector
Y5020	DEF Dosing Injector	Injector
Y5021	Fuel Injector Harness	Injector
223673	Filter, oil	Oil filter
24-01002	Oil Filter	Oil filter
352793	Oil Filter	Oil filter
36881696	ELEMENT, ENGINE OIL FILTER	Oil filter
950-1681	Engine Oil Filter	Oil filter
C04521	Element, Oil Filter	Oil filter
DZ118286	OIL FILTER	Oil filter
GM32809	FILTER, OIL	Oil filter
GM64496	Oil Filter	Oil filter
GM77161	Oil Filter	Oil filter
GM86400	Oil Filter	Oil filter
LF3703	Lube, Spin-On	Oil filter
P-175-002	Oil Filter	Oil filter
RE504836	OIL FILTER	Oil filter
RE539279	ENGINE OIL FILTER	Oil filter
SE501813	(REMAN FOR DZ100021) (5024)	Oil pump
011068	Status: Generator at Rest, Stop Mode, 22:31	Service part / kit
011136	DANGER Electrocution. Do not disable or modify the connection box door safety switch.	Service part / kit
05-79650	Soundshield	Service part / kit
100REOZJ4	Stationary non-emergency gen-sets	Service part / kit
12547	Assembly, cam lock, qrtr turn	Service part / kit
12632	Lug Door Safety Swtiches(2)	Service part / kit
14203	Block, terminal - 10 pos.	Service part / kit
14204	Kit, ground bar	Service part / kit
17776	THROTTLE SHAFT BUSHING REPLACEMENT	Service part / kit
18556	Regulator, voltage - SE 350	Service part / kit
18893	Handle, lug door	Service part / kit
18934	Guard, potentiometer	Service part / kit
20-29601-1	Element, Intake Aftercooler	Service part / kit
21-10000	Zinc Plug	Service part / kit
21-10010	Zinc Anode	Service part / kit
22018	Hinge, continuous - 10.25	Service part / kit
22208	Hinge, control panel - 28”	Service part / kit
23025	Light, interior control panel	Service part / kit
23093	Governor linkage gap kit	Service part / kit
24-20015	Crankcase Breather Filter, Left hand	Service part / kit
24540	Holder, manual	Service part / kit
25-19511	Wear Plate	Service part / kit
25077	Switch, toggle - 20A VAC	Service part / kit
26229	Kit, voltage adjustment pot w/wires	Service part / kit
26431	ESO MOUNTING AND GROUNDING KIT	Service part / kit
26888	PROTECTIVE SHIPPING CAP	Service part / kit
26891	PROTECTIVE SHIPPING CAP	Service part / kit
27828	Panel, lug box glastic	Service part / kit
28561W	Box, lug enclosure	Service part / kit
28564W	Panel, control left	Service part / kit
28567	Bus, main breaker out	Service part / kit
28569W	Panel, lug box outlet	Service part / kit
28570W	Door, lug box	Service part / kit
28583W	Angle, top lug box	Service part / kit
28584	Bus, lug extension	Service part / kit
28653B	Weldment, control box	Service part / kit
28910	SPRING, pressure adjusting	Service part / kit
29893	Bracket, control board wire guide	Service part / kit
2x594	Ampere rating	Service part / kit
30175	Decal, UN31A tank caution	Service part / kit
30246W	Panel, digital control	Service part / kit
32966	O.S. METERING VALVE AND ARM ASSEMBLY	Service part / kit
33002	SEAT, spring	Service part / kit
34195	VALVE BODY	Service part / kit
34270	COIL ASSEMBLY	Service part / kit
34488	HOUSING AND ADVANCE PISTON KIT	Service part / kit
36493	HEAD AND ROTOR KIT	Service part / kit
37055	CSA SOLENOID KIT 12V NON-DELAY	Service part / kit
38411	CONNECTOR, back-leakage	Service part / kit
51551	Decal set, safety	Service part / kit
51552	Decal, high temp	Service part / kit
54-51006	Drain Valve, Metal	Service part / kit
54005	CAP, DEF FILL	Service part / kit
55104	CAP, FUEL FILL 3.50 - GREEN	Service part / kit
60020	Nut, M8-1.25 sflg lock	Service part / kit
60062	Screw, 10-32 x .750 pan phil, G2	Service part / kit
60068	Screw, 10-24X.500 pan phil	Service part / kit
60145	Nut, .375-16 ser flg lock	Service part / kit
60161	Nut, .250-20 hx ser flg	Service part / kit
60168	Screw, .312-18X.750 hx hd	Service part / kit
60175	Screw, .250-20X.500 sflg hex	Service part / kit
60252	Washer, #10 split lock	Service part / kit
60268	Rivet, .188 dia. x .126 to .250 grip, SS	Service part / kit
60270	Nut, 8-32 nylock, G6	Service part / kit
60398	Screw, 10-32 x .500 pan phil, SS	Service part / kit
60452	Washer, .313 flat 1.125/1.0 bonded rubber, SS	Service part / kit
60473	Rivet, 3/16	Service part / kit
60478	Screw, .375-16X2.000 hx hd	Service part / kit
60505	Nut, .312-18 U-clip - long type	Service part / kit
60507	Screw, .312-18x1.0 std hex, SS	Service part / kit
60525	Screw, 8-32X1.500 pan phil	Service part / kit
6068HF120-183	Engine	Service part / kit
60749	Plug, hole .500 dia. white	Service part / kit
61045	Nut, 10-32 sflg	Service part / kit
65309	Connector, 21 pin, deutsch	Service part / kit
65444	Transformer, current	Service part / kit
655K	Ground Contact Area	Service part / kit
65890	Lug, terminal dual #6-350mcm	Service part / kit
66191	Controller, eng/gen - prog.	Service part / kit
66455	Relay, 12V/70A NC/80A NO w/diode	Service part / kit
80REOZJ4	Stationary non-emergency gen-sets	Service part / kit
85401081	COOLANT HEATER RESISTANCE 1000W 240V	Service part / kit
85403616	ELECTRONIC ACTUATOR	Service part / kit
85403731	STARTING BATTERY 12V 100Ah 450A	Service part / kit
85404267	AIR HEATER RESISTANCE 1200W 12V	Service part / kit

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

Also used in

John Deere 200LC — Excavator
John Deere 360DC — Skid Steer Loader
John Deere 360DG — Skid Steer Loader
John Deere 460DG — Skidder
John Deere 540G II — Skidder
John Deere 540G III — Skidder
John Deere 548G — Skidder
John Deere 548G II — Skid Steer Loader
John Deere 640D — Skid Steer Loader
John Deere 648D — Skidder
John Deere 790E LC — Excavator
John Deere 9400 — Combine

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.

Common questions

What is the oil capacity of the John Deere 6068TFM?

The John Deere 6068TFM engine has an oil capacity of 19.4 liters.

What is the displacement of the John Deere 6068TFM?

The John Deere 6068TFM has a displacement of 6.8 liters.

Which generators use the John Deere 6068TFM engine?

The John Deere 6068TFM powers 1 generator set(s), including Cummins/Onan MDDC.

What is a common problem with the John Deere 6068TFM engine?

A commonly reported issue on generators using the John Deere 6068TFM is: Engine Coolant Temperature, Above Normal.