Yanmar 4TNV84T Troubleshooting
| Engine Model: Yanmar 4TNV84T |
| Engine Type: 4-cycle 4-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 121.7 cu.in (1.99 L) |
| Rated Engine Power: 55.2 Hp (41.3 kW) at 3000 rpm |
| Aspiration Type: Turbocharged |
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| Engine starts hard or doesn't start |
Dirty fuel filter - Service or replace the filter.
There is air in the fuel system - Bleed the system.
Clogged or defective injection nozzles - Check injection nozzles and replace if required.
Damaged fuel injection pump - Change or repair the pump.
Incorrect valve timing - Correct or replace timing gear.
Restricted fuel pipes - Service or replace fuel pipes.
Injection timing is wrong - Set up as recommended.
Cylinder or piston rings are worn - Replace faulty components.
| Diesel starts and then shuts off |
Clogged fuel filter - Replace the filter element.
Fuel injection pump is defective - Rebuild or replace pump.
Dirty air cleaner - Clean or change the filter.
Nozzle opening pressure is not adjusted - Set up as recommended.
| Engine stalls after running |
Improper fuel injection timing - Adjust according to specifications.
Clogged fuel filter - Install new filter element.
Engine is not fully warmed up - Engine is not warmed up to the required temperature.
Stuck or clogged injection nozzle - Clean or change injection nozzles.
Low idle speed setting is not correct - Adjust the low idle speed.
The valve clearance is not adjusted - Adjust valve clearance according to specifications.
Fuel injection pump malfunctioning - Repair or install a new fuel pump.
Faulty fuel injection nozzles - Replace injection nozzles.
Restricted fuel lines or hoses - Fuel lines and hoses need to be cleaned.
Air filter is clogged - Clean air cleaner element.
Damaged cylinder-head gasket - Cylinder-head gasket replacement required.
Unadjusted injection timing - Adjust as recommended.
Fuel injection pump is defective - Replacement or repair required.
One of moving engine parts has broken - Change or repair damaged parts.
Radiator fins are dirty or radiator cap is defective - Clean radiator or replace cap.
Insufficient coolant - Add coolant fluid to cooling system and also check it for leaks.
Loose or defective fan belt - Change as required.
Engine oil insufficient - Need to add engine oil.
Cylinder head gasket is damaged - Gasket should be replaced.
Injection timing is incorrect - Adjust according to specifications.
Lack of oil - Fill crankcase to proper oil level.
Oil pump is defective - Install a new pump.
Oil filter clogged - Replace or clean engine oil filter element.
Relief valve is stuck or worn - Replace or service relief valve.
Excessive oil clearance of crankshaft bearing - Inspect and replace or repair faulty parts.
Crankpin bearing clearance is excessive - Test and replace or repair worn components.
| Excessive engine oil consumption |
Oil leaking: Gaskets or seals can be faulty - Install new components.
Incorrect oil viscosity - Fill up with the proper oil viscosity.
Seized or wear piston rings - Change piston rings.
Damaged valve guides or valve stems - Need to replace the valves.
Scuffed cylinder liners or pistons - Inspect liners and pistons, replace as necessary.
Low coolant temperature - Warm up to required temperature.
Engine oil level low - Add oil to the engine crankcase.
Fuel injection pump timing is not adjusted - Set up as recommended.
Pistons are worn or scored - Have pistons replaced.
Connecting rod is worn or not aligned - Alignment procedure or replacement is required.
Battery voltage is low - Recharge the battery.
Battery won’t hold charge - Service or change the battery.
Disconnected cables or faulty battery terminals - Connect wires properly or change terminals.
Battery is discharged or worn - Replace or charge as required.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Low battery capacity - Battery is drained, charge it.
Starter motor failing - Repair or install a new starter.
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