Q: What will cause a motor to knock?

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How do I fix this knocking noise?

My car has 18000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. Engine knock is typically caused by excessive clearance in the lower engine bearings (rod and main). Of course, to know for certain, a professional would need to listen to the noise firsthand. Spark knock, which is the result of abnormal combustion, can also result in a knocking or pinging noise. Loose torque converter bolts or a cracked flex plate can also do the same. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

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