Yanmar 4TN84T Troubleshooting
| Engine Model: Yanmar 4TN84T |
| Engine Type: 4-cycle 4-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 116.3 cu.in (1.91 L) |
| Rated Engine Power: 54 Hp (40.3 kW) at 2900 rpm |
| Aspiration Type: Turbocharger |
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| Engine difficult to start or won't start |
Clogged fuel filter - Change filter element.
Air in fuel system - Bleed fuel system.
Fuel injection nozzles are clogged or faulty - Clean or change injection nozzles.
Damaged fuel injection pump - Rebuild or install a new injection pump.
Unadjusted valve timing - Set the valve timing correctly.
Dirt in the fuel lines or hoses - Clean fuel pipes.
Injection timing is wrong - Adjust according to specifications.
Worn piston rings and cylinder - Replace defective parts.
| Engine stalls after starting |
Fuel filter plugged - Change filter element.
Fuel injection pump is not working correctly - Change or repair the pump.
Air filter plugged - Service or replace the air filter.
Improper nozzle opening pressure - Set up as recommended.
| Engine stalls during operation |
Improper fuel injection timing - Set it up as required.
Fuel filter element clogging - Service the filter.
Coolant temperature is low - Warm up to required temperature.
Injection nozzles are jammed or clogged - Repair or change injection nozzles.
Incorrectly adjusted low idle speed - Correct low idle adjustment.
Valve out of adjustment - Check and adjust.
Fuel injection pump is broken - Replace or repair injection pump.
Clogged or burnt injection nozzle - Inspect nozzles and replace if necessary.
Dirt in the fuel lines or hoses - Clean fuel system hoses and lines.
Intake air restriction - Air filter maintenance required.
Cylinder head gasket is blown - Replace cylinder head gasket.
Injection timing is incorrect - Adjust as recommended.
Fuel injection pump is damaged - Rebuild or replace pump.
One of moving engine components is worn - Replace or repair damaged components.
Damaged radiator cap or dirty radiator core - Change cap or clean radiator.
Low engine coolant - Add coolant and check the components of cooling system.
Fan belt is loose or defective - Install new fan belt.
Lack of engine oil - Fill up the oil to required level.
Cylinder-head gasket is broken - Replace the gasket as required.
Injection timing is wrong - Check injection timing adjustment.
| Insufficient oil pressure |
Insufficient engine oil - Fill the crankcase with oil.
Oil pump is defective - Inspect and change as required.
Plugged engine oil filter - Change or clean engine oil filter element.
Relief valve is seized or worn - Relief valve need to be replaced or cleaned.
Excessive oil clearance of crankshaft bearing - Check and change or repair defective parts.
Excessive oil clearance of crankpin bearing - Check and replace or repair defective parts.
| Diesel engine consuming too much oil |
Oil leaking: Damaged seals or gaskets - Install new components.
Crankcase oil too light - Use proper viscosity oil.
Worn or stuck piston rings - Change the piston rings as required.
Valve guides or stems are damaged - Change the valves.
Worn pistons or cylinder liners - Inspect pistons and liners, fit new components as necessary.
| Abnormal engine noise or knocking |
Engine is cold - Normalize the temperature by warming up the engine.
Engine oil insufficient - Checking oil level and add if necessary.
Wrong setting of fuel injection pump timing - Set it up as required.
Pistons are worn or scored - Pistons need to be replaced.
Misaligned or defective connecting rod - Connecting rod needs to be aligned or changed.
Low battery output voltage - Battery is drained, charge it.
Battery is draining quickly - Battery needs to be serviced or replaced.
Bad terminals or disconnected battery cables - Connect wiring properly or install new terminals.
Battery is discharged or worn - Charge or change the battery.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery capacity - Recharge the battery.
Starter motor is damaged - Repair or change starter.
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