Yanmar 3TNM68 Troubleshooting
| Engine Model: Yanmar 3TNM68 |
| Engine Type: 4-cycle vertical 3-cylinder indirect injection liquid-cooled diesel |
| Total Displacement: 47.8 cu.in (0.78 L) |
| Rated Engine Power: 18.9 Hp (14.1 kW) at 3600 rpm |
| Aspiration Type: Naturally aspirated |
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| Engine starts hard or won't start |
Fuel filter plugged - Clean the filter element.
Air in fuel tank - Bleed fuel tank.
Dirty or faulty injection nozzles - If necessary, replace with a new nozzle.
Fuel injection pump failure - Repair or replace injection pump.
Wrong valve timing - Adjust or replace timing gear.
Restricted fuel pipes - Service fuel pipes.
Incorrect injection timing - Adjust as recommended.
Piston rings and cylinder are worn - Replace faulty components.
| Diesel starts but then stops |
Fuel filter element is dirty - Change filter element.
Defective fuel injection pump - Replace injection pump or repair it.
Air filter clogged - Replace air filter element.
Nozzle opening pressure is incorrect - Adjust according to specifications.
| Engine shuts off while running |
Wrong setting of fuel injection pump timing - Adjust as recommended.
Fuel filter element is clogged - Filter maintenance required.
Engine is not warmed up to the required temperature - Warm up engine as required.
Injection nozzles are burnt or jammed - Repair or replace injection nozzles.
| Engine stalls at low idle speed |
Low idle speed setting is not correct - Test and adjust.
Improper valve clearance - Check and adjust.
Damaged fuel injection pump - Change pump or rebuild it.
Fuel injection nozzles fault - Change fuel injection nozzles.
Dirty fuel lines or hoses - Fuel lines and hoses need to be cleaned.
Restricted intake air - Change air filter element.
Cylinder-head gasket is leaking - Replace cylinder head gasket.
Incorrect injection timing - Use correct injection timing adjustment.
Faulty fuel injection pump - Install a new pump or rebuild.
One of moving engine components is worn - Repair or replace defective components.
Defective radiator cap or clogged radiator fins - Replace cap or clean radiator.
Low coolant level - The cooling system needs to be refilled and checked for faults.
Broken or loose fan belt - Belt change is required.
Engine oil insufficient - Check and refill engine oil.
Defective cylinder head gasket - Change cylinder head gasket.
Injection timing is out of adjustment - Set the injection timing correctly.
Engine oil insufficient - Need to add oil.
Oil pump failure - Repair or change.
Oil filter element clogged - Change or clean engine oil filter element.
Relief valve is defective or dirty - Replace or service relief valve.
Excessive crankshaft bearing clearance - Test and replace or repair worn components.
Crankpin bearing clearance is excessive - Check and replace or repair defective parts.
| High engine oil consumption |
Oil leakage: Damaged gaskets or seals - To repair leaks, replace worn parts.
Oil viscosity is wrong - Use oil of correct viscosity.
Piston rings are seized or worn - Piston rings replacement required.
Damaged valve stems or valve guides - Valves need to be changed.
Pistons or cylinder liners are damaged - Check pistons and liners, replace as required.
| Abnormal engine noise or knocking |
Engine is not warmed up to the required temperature - Warm up engine as required.
Engine oil level is insufficient - Check and refill engine oil.
Timing of fuel injection pump is incorrect - Adjust according to specifications.
Pistons are scored or worn - Replace the pistons.
Connecting rod is not aligned or defective - Connecting rod must be aligned or replaced.
Battery power is low - Recharge the battery.
Battery will not hold charge - Service or change the battery.
Wires are disconnected or battery terminals are corroded - Check cables and service or change terminals.
Battery is low or faulty - Recharge or change battery.
Disconnected or incorrectly connected wires - Inspect battery wires and connect correctly.
Low battery output voltage - Recharge the battery.
Faulty starter motor - Starter needs to be changed.
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