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
| Oil capacity | 19.4 L |
|---|---|
| Coolant capacity | 30.0 L |
| Displacement | 6.8 L |
| Aspiration | turbocharged |
| Rated speed | 1800 rpm |
Compiled from service & troubleshooting documentation across every generator set that uses the John Deere 6068TFM.
| 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.
| 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 | 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 | 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 | 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 | |
| Pressure | Maximum Pump Inlet Restriction | 100 | inches H20 | |
| Pressure | Maximum Pump Inlet Restriction | 120 | inches H20 | |
| Pressure | Minimum Fuel Inlet Pressure | - 3.5 | psi | |
| Pressure | Minimum Fuel Inlet Pressure with Auxiliary Pump | - 8.5 | psi | |
| Pressure | Recommended Pressure Cap | 10 | psi | |
| Pressure | Recommended Pressure Cap | 70 | kPA |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Fluid | Grade | Standard | Ambient | 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.
| Code | Name | Meaning | Severity | Action |
|---|---|---|---|---|
| 1 | One blink | Shutdown due to high engine temperature | Shutdown | |
| 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 | The e-Series Digital Display will display this if the auxiliary engine shutdown device causes shutdown | Shutdown | See the Operator Manual. |
| 2 | Two blinks | Shutdown due to low oil pressure | Shutdown | |
| 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 |
| 3 | Three blinks | Shutdown that may require service | Warning | See Troubleshooting in the Operator's Manual |
| 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 |
| 4 | Overcrank | Shutdown due to a failure to start within the time allowed for cranking | 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 |
| 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 |
| 5 | Warning Shutdown due to CO | The e-Series Digital Display will display this if the CO detector causes shutdown | Shutdown | See the Operator Manual. |
| 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 | The genset will shut down if exhaust temperature becomes too high | 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 |
| 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 |
| 61 | External Shutdown | The e-Series Digital Display will display this if the external stop device causes shutdown | Shutdown | See the Operator Manual. |
| 7 | Seven blinks | The genset will shut down if water stops flowing | Shutdown | Open sea cock; clean sea water strainer; check hoses; check raw water impeller; check hull through-fitting |
| 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 158, FMI: 17 | Battery Potential, Below Normal | ECU cannot power down | 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: 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: 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: 2000, FMI: 06 | ECU Failure, Cur. Out/Range | ECU failure | Shutdown | 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: 10 | Timing (Crank) Sensor, Abnormal Rt/Chg. | Improper signal pattern | Warning | 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: 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: 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 |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Tools: Separate voltmeter
Tools: Small flat-bladed screwdriver
⚠ Hazardous Voltage! Touching uninsulated live parts can result in severe personal injury or death.
⚠ Hazardous voltage - touching uninsulated live parts can cause severe personal injury or death
Tools: Small flat-bladed screwdriver
⚠ Backflow can cause major engine damage if the cylinders become flooded.
⚠ Sparks can ignite fuel leading to severe personal injury or death. Do not run battery cables and fuel lines together.
Tools: Insulated wrench
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
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.
The John Deere 6068TFM engine has an oil capacity of 19.4 liters.
The John Deere 6068TFM has a displacement of 6.8 liters.
The John Deere 6068TFM powers 1 generator set(s), including Cummins/Onan MDDC.
A commonly reported issue on generators using the John Deere 6068TFM is: Water In Fuel Indicator, Above Normal.