What Causes the Exhaust Valve to Hit the Piston?

1 Answers
TaliaMarie
07/25/25 3:01am
The exhaust valve hitting the piston is caused by increased clearance in bearing and bushing fits. Reasons for bearing wear: After prolonged use, the fitting clearance between the main bearings, connecting rod bearings, and crankshaft journals, as well as between the piston pins and connecting rod bushings, increases due to wear. During the reciprocating motion of the piston in the cylinder liner, the piston crown may exceed its original top dead center position due to inertial forces, leading to collision with the opening valve head. Reasons for loose connecting rod bolts: Loose connecting rod bolts increase the clearance between the connecting rod bearings and crankshaft journals. Under inertial forces, the connecting rod's upward travel height increases, causing the piston to strike the valve head. If not addressed promptly, the connecting rod bolts are highly prone to breaking, resulting in cylinder damage.
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