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911pcars 911pcars is offline
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Join Date: Jul 2000
Location: So. Calif.
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At that idle speed, short out each cylinder in turn (R&R spark plug wire). It the knocking goes away, usually indicates a con rod bearing issue (excessive clearance). If knock is constant and louder, could be main bearing issues.

Localized hearing with screwdriver, hose, stethoscope, etc. as Phil suggests is also a good idea.

Sherwood
Old 01-08-2021, 02:57 PM
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