Mitsubishi S4S Troubleshooting
| Engine Model: Mitsubishi S4S |
| Engine Type: 4-cycle inline 4-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 203.3 cu.in (3.33 L) |
| Rated Engine Power: 63 Hp (47 kW) at 2500 rpm |
| Fuel System Type: Indirect fuel injection |
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| Diesel engine hard to start or doesn't start |
Dirty fuel filter - Clean or replace the filter.
Air in the fuel lines - Bleed the fuel lines.
Clogged or defective injection nozzles - Check and replace nozzles if required.
Fuel injection pump is not operating properly - Change pump or rebuild it.
Incorrect valve timing - Set the valve timing correctly.
Fuel pipes are plugged - Service or change fuel pipes.
Unadjusted injection timing - Adjust injection timing as required.
Cylinder or piston rings are worn - Change defective parts.
| Engine starts but then stops |
Fuel filter element is clogged - Service or replace the filter.
Fuel injection pump is not operating properly - Replace or repair injection pump.
Dirty air cleaner - Clean or replace element.
Incorrect nozzle opening pressure - Set it correctly.
| Engine stalls during operation |
Fuel injection timing is not adjusted - Use the correct fuel injection pump timing adjustment.
Fuel filter plugged - Service or replace the filter.
Engine is not preheated - Warm up engine as required.
Stuck or burnt injection nozzle - Repair or replace injection nozzles.
Low idle speed adjustment is incorrect - Adjustment required.
Valve clearance is wrong - Correct valve clearance.
Fuel injection pump is broken - Repair or install new pump.
| Diesel engine is losing power |
Clogged or defective injection nozzles - Service or change injection nozzles.
Restricted fuel hoses or lines - Clean fuel hoses and lines.
Plugged air cleaner - Change air filter element.
Worn cylinder head gasket - Gasket should be replaced.
Improper injection timing - Adjust injection timing as required.
Fuel injection pump malfunctioning - Replace or repair injection pump.
One of moving engine components has failed - Replace or repair damaged components.
Defective radiator cap or clogged radiator fins - Replace cap or clean radiator.
Low engine coolant - Add coolant fluid to cooling system and also check it for leaks.
Fan belt is loose or defective - Fan belt must be replaced.
Engine oil level is low - Add oil to the engine crankcase.
Damaged cylinder-head gasket - Replace cylinder head gasket.
Injection timing is wrong - Adjust according to specifications.
Engine oil level low - Add oil to the engine crankcase.
Oil pump failure - Inspect and change as required.
Oil filter element is dirty - Replace or service engine oil filter.
Worn or dirty relief valve - Replace or service relief valve.
Clearance of crankshaft bearing is excessive - Check and replace or repair defective parts.
Clearance of crankpin bearing is excessive - Test and replace or repair worn components.
| Engine oil consumption is too high |
Oil leakage: Defective seals or gaskets - Change worn parts according to specifications.
Oil viscosity is incorrect - Use oil of proper viscosity.
Piston rings are defective or worn - Piston rings need to be replaced.
Valve guides and stems are worn - Need to replace the valves.
Scuffed pistons or cylinder liners - Inspect pistons and liners, fit new components as necessary.
| Abnormal engine noise or knocking |
Engine is not preheated - Warm up the engine.
Lack of engine oil - Fill up the engine oil.
Incorrect adjustment of fuel injection pump timing - Check the fuel injection pump timing adjustment.
Worn or broken pistons - Have pistons replaced.
Connecting rod is not aligned or defective - Connecting rod must be aligned or replaced.
Low battery power - Low battery charging, charge as required.
Battery discharges quickly - Service or change the battery.
Bad battery terminals or disconnected wiring - Check cable connections and replace or service terminals.
Battery is low or faulty - Recharge or change battery.
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required.
Low battery voltage - Recharge the battery.
Starter motor is damaged - Starter needs to be changed.
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