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Condition Possible cause Correction
Abnormal detonation Abnormal condition in engine
1. Excessive carbon deposit on piston crowns or cylin-
der head
2. Blown cylinder head gasket, resulting in low compres-
sion pressure
3. Improper valve clearance
4. Valves tending to seize
5. Weakened valve springs
Clean
Replace
Adjust
Replace
Replace
Overheating Abnormal condition in ignition system
1. Wrong heat value of spark plugs
Abnormal condition in fuel system
3. Loose inlet manifold
Abnormal condition in cooling system
1. Not enough coolant
2. Loose or broken water pump belt
3. Erratically working thermostat
4. Poor water pump performance
5. Leaky radiator cores
Abnormal condition in lubrication system
1. Clogged oil filter
2. Clogged oil strainer
3. Deteriorated oil pump performance
4. Oil leakage from oil pan or pump
5. Improper engine oil grade
6. Not enough oil in oil pan
Others
1. Dragging brakes
2. Slipping clutch
3. Blown cylinder head gasket
Change heat valve
Retighten
Refill
Adjust or replace
Replace
Replace
Repair or replace
Replace
Clean
Replace
Repair
Replace with proper grade oil
Replenish
Repair or replace
Adjust or replace
Replace