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Q: Knocking when driving

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My car knocking when slowing down and changing gear

My car has 81000 miles.
My car has a manual transmission.

A: An engine can ping (or knock) due to an imp...

An engine can ping (or knock) due to an improper combustion process. An ignition knock is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). In extreme cases, engine knock can be the result of a connecting rod failing which is a much larger problem that often times requires the removal of the engine to replace these bearings. I would recommend having an expert from YourMechanic come to your location to diagnose your engine knock.

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