Engine Repair (A1)第 4 / 120 题
On an overhead-cam engine, excessive valve lash (clearance) most commonly produces which symptom?
a.Blue exhaust smoke
b.Loss of coolant
c.Low oil pressure
d.A clicking or tapping noise from the valvetrain
解析
Too much clearance in the valvetrain lets components hammer against one another, producing a rhythmic tapping that changes with engine speed. Insufficient lash, by contrast, can hold valves open and burn them. Proper adjustment restores quiet operation and correct valve timing.
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