John Deere 6068HF120 Troubleshooting
| Engine Model: John Deere 6068HF120 |
| Engine Type: 4-cycle inline 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 415 cu.in (6.8 L) |
| Rated Engine Power: 188-245 Hp (140-183 kW) at 1800 rpm |
| Fuel System Type: Direct fuel injection |
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| Diesel hard to start or doesn't start |
Fuel filter plugged - Service the filter.
Air trapped in fuel system - Bleed air.
Clogged or burnt injection nozzle - Install a new kit of correctly balanced nozzles.
Fuel injection pump is not operating properly - Rebuild or change fuel pump.
Wrong valve timing - Set the valve timing correctly.
Dirt in the fuel lines or hoses - Service or replace fuel pipes.
Injection timing is out of adjustment - Use correct injection timing adjustment.
Worn piston rings and cylinder - Replace defective parts.
| Engine starts but stalls immediately |
Fuel filter plugging - Clean the filter or install new filter element.
Fuel injection pump failure - Install a new fuel pump or repair.
Plugged air cleaner - Air filter maintenance required.
Nozzle opening pressure is incorrect - Adjust as required.
| Engine stalls during operation |
Improper setting of fuel injection pump timing - Adjust according to specifications.
Dirty fuel filter - Filter maintenance required.
Engine not warmed up - Engine is not warmed up to the required temperature.
Injection nozzles sticking or clogged - Check injection nozzles and replace if required.
Incorrect low idle speed adjustment - Need to adjust idle speed.
The valve clearance is incorrect - Check and adjust.
Fuel injection pump damage - Rebuild or change fuel pump.
| Diesel engine loses power |
Fuel injection nozzles are damaged - Clean or replace injection nozzles.
Fuel hoses or lines are dirty - Clean fuel system hoses and lines.
Clogged air filter element - Service air cleaner.
Defective cylinder head gasket - Install new cylinder head gasket.
Injection timing is incorrect - Adjust as recommended.
Fuel injection pump is faulty - Repair or replace injection pump.
One of moving engine components is worn - Repair or replace defective components.
Faulty radiator cap or dirty radiator fins - Install new cap or clean radiator.
Engine coolant is insufficient - Refill to the correct level and inspect system for leaks.
Broken or loose fan belt - Belt replacement is recommended.
Engine oil level is low - Need to add engine oil.
Cylinder head gasket is worn - Gasket should be replaced.
Wrong injection timing - Set up as recommended.
| Insufficient oil pressure |
Oil level is low - Add oil to the engine crankcase.
Worn oil pump - Replace as required.
Clogged oil filter - Service or replace engine oil filter.
Relief valve is stuck or broken - Change or service relief valve.
Clearance of crankshaft bearing is excessive - Test and repair or replace worn parts.
Excessive oil clearance of crankpin bearing - Test and repair or replace worn parts.
| Diesel engine consuming too much oil |
Oil leaking: Defective seals or gaskets - Change to repair leaks.
Oil viscosity is wrong - Use proper viscosity oil.
Piston rings are seized or worn - Change piston rings.
Valve guides or stems are damaged - Replace defective valves.
Scored cylinder liners or pistons - Inspect liners and pistons, change as necessary.
Coolant temperature is low - Engine is not warmed up to the required temperature.
Low engine oil level - Fill up the engine oil.
Improper setting of fuel injection pump timing - Set it up as required.
Broken or worn pistons - Pistons replacement required.
Connecting rod failure or misalignment - Align or change connecting rod.
| Starter motor cranks slow |
Battery voltage is low - Battery is drained, recharge it.
Battery does not hold charge - Service or change the battery.
Bad terminals or disconnected battery cables - Connect wires properly or change terminals.
Battery is low or faulty - Recharge or change battery.
Wiring harness is disconnected or improperly connected - Check wiring harness and connect as required.
Battery power is low - Battery is drained, recharge it.
Defective starter motor - Starter needs to be changed.
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