Yanmar 4TNV84 Troubleshooting
| Engine Model: Yanmar 4TNV84 |
| Engine Type: 4-cycle 4-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 121.7 cu.in (1.99 L) |
| Rated Engine Power: 44.1 Hp (32.9 kW) at 3000 rpm |
| Aspiration Type: Naturally aspirated |
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| Engine hard to start or will not start |
Fuel filter element is clogged - Change the filter element.
Air in the fuel pipes - Bleed the fuel pipes.
Dirty or damaged injection nozzles - If necessary, replace with a new nozzle.
Fuel injection pump is defective - Replace injection pump or repair it.
Unadjusted valve timing - Use correct valve timing adjustment.
Fuel pipes are plugged - Clean or change fuel pipes.
Unadjusted injection timing - Adjust according to specifications.
Damaged piston rings and cylinder - Change defective parts.
| Engine starts and then shuts off |
Fuel filter plugging - Change the filter element.
Fuel injection pump malfunctioning - Change or repair the pump.
Dirty air cleaner - Service air cleaner.
Nozzle opening pressure is not adjusted - Set up as recommended.
| Engine stops unexpectedly during operation |
Fuel injection timing is wrong - Check the fuel injection pump timing adjustment.
Fuel filter element clogging - Change the filter element.
Low coolant temperature - Warm up to required temperature.
Defective or stuck injection nozzles - Change or repair injection nozzles.
Incorrectly set low idle speed - Adjust low idle speed.
Valve clearance is not correct - Need to adjust valve clearance.
Faulty fuel injection pump - Install a new fuel pump or repair.
Fuel injection nozzles are damaged or dirty - Clean or replace injection nozzles.
Fuel lines or hoses clogging - Clean fuel lines and hoses.
Air filter element clogged - Air filter maintenance required.
Worn cylinder head gasket - Change cylinder head gasket.
Improper injection timing - Set the injection timing correctly.
Faulty fuel injection pump - Install a new fuel pump or repair.
Any of moving engine components is faulty - Replace or repair damaged components.
Dirty radiator core or defective radiator cap - Clean radiator or change cap.
Low coolant level - Refill to the correct level and inspect system for leaks.
Fan belt is loose or defective - Fan belt must be replaced.
Engine oil level is low - Checking oil level and add if necessary.
Cylinder head gasket is damaged - Change cylinder head gasket.
Wrong injection timing - Set up as recommended.
Low crankcase oil level - Fill crankcase to proper oil level.
Defective oil pump - Repair or change.
Engine oil filter is plugged - Change or service engine oil filter.
Relief valve is defective or dirty - Replace or clean relief valve.
Crankshaft bearing clearance is excessive - Inspect and replace or repair faulty parts.
Clearance of crankpin bearing is excessive - Check and change or repair defective parts.
| Engine consuming too much oil |
External oil leaks: Gaskets or seals may be damaged - Install new components.
Crankcase oil too light - Fill up with the proper oil viscosity.
Worn or broken piston rings - Change the piston rings as required.
Valve guides or stems are damaged - Valves must be replaced.
Worn cylinder liners or pistons - Check liners and pistons, install new components as required.
| Abnormal engine knocking or noise |
Engine is not preheated - Warm up to required temperature.
Not enough engine oil - Check and refill engine oil.
Timing of fuel injection pump is incorrect - Set it up as required.
Pistons are worn or scored - Have pistons replaced.
Misaligned or faulty connecting rod - Alignment procedure or replacement is required.
Low battery capacity - Battery needs to be recharged.
Battery runs out quickly - Service battery or replace it.
Faulty battery terminals or disconnected cables - Check wire connections and change or service terminals.
Battery is discharged or worn - Battery needs to be recharged or replaced.
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed.
Low battery output - Battery needs to be recharged.
Starter motor is damaged - Starter needs to be changed.
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