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post #1 of 3 (permalink) Old 02-26-2012, 06:00 PM Thread Starter
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Engine Making Odd Noise While in Drive

06 LS 2.2 automatic no mods, engine is making a loud sort of "knocking/shuddering" noise while the brake pedal is held while in drive and the noise is louder with the a/c on. Once I let off the brake pedal, or shift into neutral with the brake pedal still held, the noise stops. Not sure exactly what part of the motor the noise is coming from either. Thanks for the help
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post #2 of 3 (permalink) Old 02-27-2012, 07:17 AM
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I know you'll get some great feedback from technically savvy posters on the forum; I just wanted to offer my assistance if you should choose to work with a dealership on getting this diagnosed.

All the best,
GM Customer Service
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post #3 of 3 (permalink) Old 02-27-2012, 12:56 PM
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Sounds like something is going on with your transmission/flywheel/torque converter, not a mechanic but sounds like somethings slipping inside.

I gather that since it only happens when its in gear and your applying the brake.

You should apply your parking break, put your car in gear, then carefully check the engine and try to find exactly where this sound is coming from. Just make sure your car does not roll away, or have someone be inside while you check, you may or may not hear the knocking sound with the parking brake vs the pedal brake, if the noise only occurs when applying the pedal brake, you will have to get someone to press it for you, or prop it down with something while you check.

Old Car: Chevy Cobalt 2006 LS Sedan base (Automatic)

New Car: Chevy Impala 2011 LT Fully Loaded (Automatic)
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