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Q: Loud Knock

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Knocking noise under car after start up, didn't start until put I drive and slightly driven up the hill in my driveway then put in reverse when I notice and came back down. Now at idle loud knocking noise and car barely stays on. After pressing on the gas, the knock dies down but starts back up at idle. Any clues?

My car has 110000 miles.
My car has an automatic transmission.

A: Hi there: In most cases a knocking sound a...

Hi there:

In most cases a knocking sound at idle is caused by metal to metal wear. Some of the common causes of this condition include low oil pressure or low oil levels inside the motor or transmission, damage to suspension or driveline components due to striking a curb, pothole or other object or loose pulley's that power the serpentine belt or the belt itself that is causing this noise to occur. To know for sure, you should have a professional mechanic complete a car is making a noise inspection; so they can pinpoint the source of this noise and recommend the right repairs.

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