PISTON FAILURE

PISTON - BURNT OUT
This is where the outer edge of the crown of the piston is severely eroded. The damage has the appearance of being burnt or exploded away. This damage is the direct result of severe detonation over a long period. In petrol engines the causes for detonation are usually, over advanced ignition timing (base or total advance), compression too high or incorrect octane rating of the fuel.

Excessive deposits of carbon or hot spots in the combustion chambers (sharp edges that are thin enough to glow red-hot and cause pre ignition). Incorrect spark plugs, spark cross firing and incorrect air/ fuel ratio can also result in pre ignition.

Diesel engines suffer the same type of damage and is usually caused by faulty injectors, injector pump or pump timing.

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Piston Crown Burnt
due to detonation