The ablation surface of piston appears to be pear-shaped skin and dark grey,main reason invlove:
Abnormal combustion arising from the cause like improper adjustment between injection advance angle and knocking control system of engine may easily result in the dimpling of piston top or the ablation of ring bank.
Abnormal operation of injector gives rise to knocking of engine and easily results in piston top ablation or craking ,or more seriously breakthrough.
Abnormal operation of injector causes inferior fuel atomization ,secong injection or dropping and results in serious after-burning and overheats ablation of piston .
Bad heat dissipation or over high combustion temperature of engine results in failure emission of heat.
Inferior chemical composition and metallographic structure of piston material.