Mitsubishi S4Q2 Troubleshooting
| Engine Model: Mitsubishi S4Q2 |
| Engine Type: 4-cycle inline 4-cylinder OHV forced-feed lubrication liquid-cooled diesel |
| Total Displacement: 152.9 cu.in (2.51 L) |
| Rated Engine Power: 46.4-48.5 Hp (34.6-36.2 kW) at 2400 rpm |
| Fuel System Type: Indirect fuel injection |
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| Engine difficult to start or doesn't start |
Dirty fuel filter - Service or replace the filter.
Air in fuel tank - Bleed fuel tank.
Defective injection nozzle - Replace injection nozzles.
Fuel injection pump damage - Replacement or repair required.
Valve timing is wrong - Correct or replace timing gear.
Fuel pipes are clogged - Service fuel pipes.
Injection timing is improper - Adjust according to specifications.
Worn cylinder or piston rings - Replace defective parts.
| Diesel starts but stalls immediately |
Dirty fuel filter - Clean or replace the filter.
Fuel injection pump failure - Install a new pump or rebuild.
Air filter is clogged - Clean or change the filter.
Unadjusted nozzle opening pressure - Adjust as required.
| Engine stalls while running |
Fuel injection timing is not adjusted - Set it up as required.
Fuel filter element is clogged - Service the filter.
Engine not warmed up - Normalize the temperature by warming up the engine.
Injection nozzles are stuck or clogged - Change or repair injection nozzles.
Low idle speed adjustment is incorrect - Adjust low idling as recommended.
Incorrect valve clearance - Correct valve clearance needs to be set.
Fuel injection pump is faulty - Replace injection pump or repair it.
Damaged or dirty injection nozzles - Service or change injection nozzles.
Dirt in the fuel hoses or lines - Fuel hoses and lines must be clean.
Plugged air cleaner - Change air filter element.
Cylinder head gasket is blown - Gasket should be replaced.
Injection timing is incorrect - Adjust according to specifications.
Faulty fuel injection pump - Repair or install new pump.
One of moving engine components has failed - Change or repair damaged parts.
Dirty radiator fins or defective radiator cap - Clean radiator or replace cap.
Coolant level is low - Add coolant and check the components of cooling system.
Damaged or worn fan belt - If necessary, replace the belt.
Engine oil insufficient - Fill up the oil to required level.
Cylinder-head gasket is leaking - Install a new gasket.
Injection timing is improper - Set the injection timing correctly.
| Oil pressure is insufficient |
Low oil level - Check and refill the oil.
Worn oil pump - Inspect and change as required.
Oil filter clogging - Service or replace engine oil filter.
Worn or dirty relief valve - Replace or service relief valve.
Crankshaft bearing clearance is excessive - Test and repair or replace worn parts.
Crankpin bearing clearance is excessive - Check and change or repair defective parts.
| Engine oil consumption is too high |
Oil leaking: Worn gaskets or seals - Replace to repair leaks.
Wrong oil viscosity - Fill up with the correct oil viscosity.
Seized or wear piston rings - Piston rings replacement required.
Damaged valve stems or valve guides - Replace the valves.
Scuffed cylinder liners or pistons - Check liners and pistons, replace as required.
Engine is not preheated - Normalize the temperature by warming up the engine.
Engine oil insufficient - Checking oil level and add if necessary.
Fuel injection pump timing is not adjusted - Adjust fuel injection pump as required.
Pistons are scored or worn - Install new pistons.
Connecting rod is defective or not aligned - Replace or align connecting rod.
Battery capacity is low - Low battery charging, charge as required.
Battery is draining quickly - Service charging system or change battery.
Disconnected wiring or bad battery terminals - Connect wiring properly or install new terminals.
Battery is drained or worn - Battery needs to be recharged or replaced.
Battery cables are disconnected or improperly connected - Inspect cables and connect properly.
Low battery power - Charge the battery.
Starter motor is faulty - Starter needs to be changed.
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