Mitsubishi S12A2 Troubleshooting
| Engine Model: Mitsubishi S12A2 |
| Engine Type: 4-cycle 12-cylinder V-block turbocharged liquid-cooled diesel |
| Total Displacement: 2,071 cu.in (33.93 L) |
| Rated Engine Power: 910-1140 Hp (679-850 kW) at 1500-1800 rpm |
| Fuel System Type: Direct injection |
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| Engine hard to start or will not start |
Fuel filter element is clogged - Filter maintenance required.
Air in fuel system - Bleed fuel system.
Fuel injection nozzles are damaged - Replace injection nozzles.
Defective fuel injection pump - Rebuild or change fuel pump.
Wrong valve timing - Adjust or change timing gear.
Dirt in the fuel lines or hoses - Service or replace fuel pipes.
Improper injection timing - Adjust injection timing as required.
Cylinder or piston rings are worn - Replace defective parts.
| Diesel starts but immediately stops |
Fuel filter plugging - Filter maintenance required.
Fuel injection pump malfunctioning - Repair or change injection pump.
Clogged air filter - Install new air filter element.
Nozzle opening pressure is improper - Adjust as required.
| Diesel shuts off while driving |
Incorrect adjustment of fuel injection pump timing - Use the correct fuel injection pump timing adjustment.
Clogged fuel filter - Clean the filter element.
Engine is not preheated - Normalize the temperature by warming up the engine.
Stuck or clogged injection nozzle - Check injection nozzles and replace if required.
Incorrect low idle speed adjustment - Adjust as required.
Valve out of adjustment - Adjustment procedure required.
Fuel injection pump malfunction - Install a new pump or rebuild.
Fuel injection nozzles are damaged - Change fuel injection nozzles.
Fuel lines or hoses are clogged - Service fuel lines and hoses.
Restricted intake air - Clean or change the filter.
Cylinder-head gasket is broken - Install a new gasket.
Injection timing is incorrect - Check injection timing adjustment.
Faulty fuel injection pump - Change or repair the pump.
One of moving engine parts has broken - Repair or replace defective components.
Radiator fins are clogged or radiator cap is faulty - Clean radiator or replace cap.
Engine coolant is insufficient - Add coolant fluid and inspect the cooling system for leaks.
Fan belt is broken or worn - Install new fan belt.
Lack of engine oil - Fill up the oil to required level.
Defective cylinder head gasket - Install a new gasket.
Injection timing is wrong - Set the injection timing correctly.
| Insufficient oil pressure |
Lack of oil - Fill the crankcase with oil.
Defective oil pump - Remove and inspect oil pump.
Clogged oil filter element - Clean or replace engine oil filter element.
Relief valve is defective or dirty - Replace or service relief valve.
Excessive oil clearance of crankshaft bearing - Test and repair or replace worn parts.
Clearance of crankpin bearing is excessive - Test and replace or repair worn components.
| Diesel engine consuming too much oil |
Oil leaks: Worn seals or gaskets - To repair leaks, replace worn parts.
Oil viscosity is wrong - Use correct viscosity oil.
Stuck or defective piston rings - Piston rings replacement required.
Valve stems and guides are worn - Need to replace the valves.
Pistons or cylinder liners are scored - Inspect pistons and liners, replace as required.
| Abnormal engine knocking or noise |
Engine is cold - Normalize the temperature by warming up the engine.
Low engine oil level - Checking oil level and add if necessary.
Incorrect adjustment of fuel injection pump timing - Set up as recommended.
Broken or worn pistons - Replace the pistons as required.
Misaligned or defective connecting rod - Connecting rod needs to be replaced or aligned.
Low battery capacity - Low battery charging, charge as required.
Battery does not hold charge - Battery needs service or replacement.
Disconnected cables or faulty battery terminals - Connect wiring correctly or install new terminals.
Battery is low or faulty - Recharge or replace battery.
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed.
Low battery output voltage - Charge the battery.
Starter motor failure - Starter needs to be replaced.
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