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Kubota D640 Troubleshooting
| Engine Model: Kubota D640 |
| Engine Type: 4-cycle vertical 3-cylinder water-cooled diesel engine |
| Total Displacement: 38.9 cu.in (0.65 L) |
| Rated Engine Power: 16 Hp (11.8 kW) at 3200 rpm |
| Fuel System: Fuel injection pump |
| Engine starts up hard or doesn't start |
Clogged fuel filter - Clean or change the filter.
Air in the fuel lines - Bleed the fuel lines.
Defective or clogged injection nozzle - Test injection nozzles and change if necessary.
Fuel injection pump is faulty - Replace injection pump or repair it.
Valve timing is incorrect - Set the valve timing correctly.
Dirt in the fuel lines or hoses - Clean or replace fuel pipes.
Incorrect injection timing - Check injection timing adjustment.
Worn cylinder or piston rings - Replace faulty components.
| Diesel starts and suddenly stops |
Clogged fuel filter - Service the filter.
Fuel injection pump malfunctioning - Repair or change injection pump.
Dirty air cleaner - Service air cleaner.
Nozzle opening pressure is incorrect - Adjust as recommended.
| Engine stalls during operation |
Improper setting of fuel injection pump timing - Use the correct fuel injection pump timing adjustment.
Fuel filter plugging - Install new filter element.
Engine is not preheated - Warm up the engine.
Stuck or clogged injection nozzle - Repair or replace injection nozzles.
Incorrect low idle speed adjustment - Adjust low idling as recommended.
Valve out of adjustment - Adjust valve clearance.
Fuel injection pump is broken - Change pump or rebuild it.
| Engine power is insufficient |
Damaged or dirty injection nozzles - Clean or change injection nozzles.
Clogged fuel lines or hoses - Fuel hoses and lines must be clean.
Air filter clogged - Carry out maintenance on air filter.
Blown cylinder head gasket - Replace cylinder head gasket.
Wrong injection timing - Set up as recommended.
Fuel injection pump is defective - Install a new pump or rebuild.
One of moving engine parts has broken - Replace or repair damaged components.
Defective radiator cap or clogged radiator core - Clean radiator or change cap.
Engine coolant is insufficient - Add coolant fluid and inspect the cooling system for leaks.
Broken or loose fan belt - Replace as required.
Lack of engine oil - Checking oil level and add if necessary.
Cylinder head gasket is defective - Replace the gasket as required.
Incorrect injection timing - Set the injection timing correctly.
Lack of oil - Fill the crankcase with oil.
Worn oil pump - Remove and inspect oil pump.
Clogged oil filter - Change or clean engine oil filter element.
Worn or dirty relief valve - Change or service relief valve.
Crankshaft bearing clearance is excessive - Inspect and replace or repair faulty parts.
Clearance of crankpin bearing is excessive - Test and replace or repair worn components.
| Excessive engine oil consumption |
Oil leaking: Defective seals or gaskets - Worn parts need to be replaced.
Incorrect oil viscosity - Use oil of proper viscosity.
Worn or broken piston rings - Piston rings need to be replaced.
Worn valve stems and valve guides - Change the valves.
Worn cylinder liners or pistons - Check pistons and liners, change as required.
| Engine knocking sound or abnormal noise |
Engine is cold - Engine is not warmed up to the required temperature.
Engine oil level is low - Checking oil level and add if necessary.
Wrong setting of fuel injection pump timing - Adjust as recommended.
Worn or scored pistons - Pistons replacement required.
Connecting rod is misaligned or defective - Alignment procedure or replacement is required.
Low battery voltage - Battery is drained, charge it.
Battery does not hold charge - Battery needs service or replacement.
Wires are disconnected or battery terminals are corroded - Check wiring connections and replace or clean terminals.
Battery is drained or worn - Recharge or replace battery.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery output voltage - Charge the battery.
Starter motor is faulty - Repair or change starter.
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