Yanmar 3TN84 Troubleshooting
| Engine Model: Yanmar 3TN84 |
| Engine Type: 4-cycle 3-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 87.2 cu.in (1.43 L) |
| Rated Engine Power: 33.5 Hp (24.9 kW) at 3400 rpm |
| Aspiration Type: Naturally aspirated |
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| Engine difficult to start or doesn't start |
Fuel filter plugged - Service or replace the filter.
Air in fuel system - Bleed fuel system.
Damaged or dirty injection nozzles - Change fuel injection nozzles.
Fuel injection pump is not working correctly - Install a new fuel pump or repair.
Wrong valve timing - Adjust or replace timing gear.
Fuel pipes are plugged - Service or change fuel pipes.
Improper injection timing - Adjust injection timing as required.
Worn cylinder or piston rings - Replace defective parts.
| Diesel starts but stalls suddenly |
Clogged fuel filter - Filter maintenance required.
Fuel injection pump is faulty - Replacement or repair required.
Plugged air cleaner - Clean or change the filter.
Nozzle opening pressure is incorrect - Adjust as recommended.
| Engine stops suddenly during operation |
Fuel injection timing is not adjusted - Adjust as recommended.
Fuel filter element is clogged - Clean or change the filter.
Engine is not fully warmed up - Warm up the engine.
Stuck or burnt injection nozzle - Repair or replace injection nozzles.
Too low idle RPM - Adjustment required.
Valve clearance is not correct - Check and adjust.
Fuel injection pump is damaged - Replacement or repair required.
Fuel injection nozzles fault - Check and replace nozzles if required.
Fuel hoses or lines are dirty - Service fuel lines and hoses.
Restricted intake air - Replace air filter element.
Cylinder head gasket defective - Cylinder-head gasket replacement required.
Injection timing is improper - Set up as recommended.
Fuel injection pump is defective - Rebuild or replace pump.
Any of moving engine components is faulty - Change or repair damaged parts.
Radiator core is clogged or radiator cap is leaking - Change cap or clean radiator.
Low coolant level - Add coolant and check the components of cooling system.
Loose or damaged fan belt - Replace the fan belt.
Engine oil insufficient - Check and refill engine oil.
Cylinder head gasket defective - Install a new gasket.
Injection timing is incorrect - Set the injection timing correctly.
Low oil level - Need to add oil.
Defective oil pump - Install a new pump.
Oil filter clogged - Clean or replace engine oil filter element.
Worn or dirty relief valve - Change or service relief valve.
Excessive oil clearance of crankshaft bearing - Check and change or repair defective parts.
Excessive crankpin bearing clearance - Inspect and replace or repair faulty components.
| Excessive oil consumption |
External oil leaks: Defective seals or gaskets - Replace worn parts to avoid leaks.
Crankcase oil too light - Fill up with the correct oil viscosity.
Worn or stuck piston rings - Piston rings need to be replaced.
Worn valve stems and valve guides - Replace the valves.
Cylinder liners or pistons are scuffed - Inspect pistons and liners, replace as required.
Engine is not warmed up to the required temperature - Warm up the engine.
Engine oil insufficient - Need to add engine oil.
Fuel injection pump timing is not adjusted - Check the fuel injection pump timing adjustment.
Scored or worn pistons - Install new pistons.
Connecting rod is defective or not aligned - Need to align or replace the connecting rod.
| Starter motor cranks slow |
Low battery output - Battery is drained, charge it.
Battery won’t hold charge - Battery needs to be serviced or replaced.
Disconnected wiring or bad battery terminals - Check wiring connections and replace or clean terminals.
Battery is low or faulty - Recharge or change battery.
Disconnected or incorrectly connected wires - Inspect battery wires and connect correctly.
Battery power is low - Low battery charging, charge as required.
Defective starter motor - Repair or change starter.
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