Yanmar 4TNV86CT Troubleshooting
| Engine Model: Yanmar 4TNV86CT |
| Engine Type: 4-cycle vertical 4-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 127.5 cu.in (2.09 L) |
| Rated Engine Power: 59.1 Hp (44 kW) at 3000 rpm |
| Aspiration Type: Turbocharged |
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| Engine starts up hard or won't start |
Fuel filter plugged - Service the filter.
Air in the fuel system - Air bleeding.
Dirty or faulty injection nozzles - Replace injection nozzles.
Fuel injection pump malfunction - Install a new pump or rebuild.
Unadjusted valve timing - Adjust or replace timing gear.
Dirt in the fuel lines or hoses - Clean or change fuel pipes.
Injection timing is incorrect - Set the injection timing correctly.
Piston rings and cylinder are worn - Change defective components.
| Engine starts and immediately shuts off |
Fuel filter element is clogged - Change the filter element.
Defective fuel injection pump - Install a new fuel pump or repair.
Air filter clogged - Service air cleaner.
Improper nozzle opening pressure - Set up as recommended.
| Engine shuts off while running |
Improper fuel injection timing - Adjust the pump as required.
Fuel filter element clogging - Change filter element.
Engine is cold - Normalize the temperature by warming up the engine.
Stuck or clogged injection nozzle - Repair or change injection nozzles.
Low idle speed setting is incorrect - Correct low idle settings.
Incorrect valve clearance - Adjustment procedure required.
Fuel injection pump malfunctioning - Replacement or repair required.
Dirty or damaged injection nozzles - If necessary, replace with a new nozzle.
Dirty fuel hoses or lines - Clean fuel lines and hoses.
Plugged air filter - Service air cleaner.
Blown cylinder head gasket - Replace the gasket as required.
Injection timing is incorrect - Adjust injection timing as required.
Fuel injection pump is damaged - Repair or replace injection pump.
One of moving engine components has failed - Repair or replace defective parts.
Faulty radiator cap or dirty radiator fins - Install new cap or clean radiator.
Coolant level is low - Top up coolant fluid and check system for leaks.
Fan belt slipping or worn - Belt change is required.
Not enough engine oil - Check oil level and add oil as required.
Defective cylinder head gasket - Install new cylinder head gasket.
Improper injection timing - Adjust as recommended.
Low oil level - Check oil level and add oil as required.
Oil pump is damaged - Install a new pump.
Oil filter clogged - Replace or clean engine oil filter element.
Relief valve is stuck or worn - Replace or clean relief valve.
Crankshaft bearing clearance is excessive - Inspect and replace or repair faulty components.
Excessive crankpin bearing clearance - Check and change or repair defective parts.
| High engine oil consumption |
External oil leaks: Gaskets or seals are excessively worn - Change to repair leaks.
Oil viscosity is incorrect - Use correct viscosity oil.
Piston rings are seized or worn - Install new piston rings.
Valve stems or guides are damaged - Install new valves.
Pistons or cylinder liners are damaged - Inspect pistons and liners, change as required.
| Engine knocking sound or abnormal noise |
Coolant temperature is low - Normalize the temperature by warming up the engine.
Engine oil level low - Fill up the engine oil.
Incorrect adjustment of fuel injection pump timing - Use the correct fuel injection pump timing adjustment.
Pistons are worn or broken - Install new pistons.
Faulty or misaligned connecting rod - Align or change connecting rod.
Battery voltage is low - Recharge the battery.
Battery will not hold charge - Service charging system or install new battery.
Disconnected wiring or bad battery terminals - Connect wiring properly or install new terminals.
Battery is drained or worn - Replace or charge as required.
Disconnected or incorrectly connected wires - Inspect battery wires and connect correctly.
Low battery voltage - Recharge the battery.
Defective starter motor - Repair or change starter.
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