Engine Repair (A1)Question 14 of 120
A rhythmic knocking noise that is loudest under load and disappears when one cylinder is disabled most likely indicates:
a.A loose accessory belt
b.An exhaust leak
c.A sticking valve
d.A worn connecting-rod bearing on that cylinder
Explanation
A rod bearing knock is load-sensitive and typically quiets when that cylinder's contribution is removed by disabling its injector or spark. Loose belts and exhaust leaks make different noises unrelated to individual cylinders. Excessive rod bearing clearance is confirmed with Plastigage during disassembly.
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