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Bang noise in transmission

cars's Avatar
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11-12-04, 06:31 AM   #1  
Bang noise in transmission

We just bought a '92 Cadillac Deville. V8-300 4.9L .
When you race the engine (in Park) , and let up, at times you get a bang noise underneath the car . If you hold your hand on the transmission pan , you can feel it . Does anyone have any idea what that can be?

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majakdragon's Avatar

Join Date: Jul 2003
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11-12-04, 06:56 AM   #2  
Are you sure it's in the tranny and not just the engine moving from the "racing"? Could be a motor mount letting the engine twist and when you let off the gas it is causing something to hit against the bottom of the car or the frame. Just a thought. Good luck and watch this post for more answers from the auto pro's.

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Join Date: Apr 2002
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11-12-04, 02:17 PM   #3  
It could be the sprag assembly in the trans and will most likely be fine if you quit reving the engine in park which by the way isn't good for any engine.

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11-12-04, 06:15 PM   #4  
Probably why you are hearing noise in the transmission is when you race the engine you are also turning transmission components such as clutch drums. These drums have ATF behind the pistons. When you race the engine, you are forcing the ATF behind the piston outward which moves the piston and starts to apply that clutch. We call it centrificaly applying the clutch. So in short, the transmission is trying to move the vehicle against the park pawl. I'm with Davo, STOP racing the engine........


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