Vibration when shifting into Drive/Reverse

[white02]

Do any of you guys have a rumbling vibration happen sometimes when you shift from park into drive or reverse? Stops when you get going and dosen't happen all the time. I would imagine it to be a consequence of the transmission tunnel and do not believe it to be a defect in the transmission itself since shifting and all other aspects of performance are smooth. Just wondering if anyone else has felt this.

 

[AZMike]

I have the same problem. Been to the dealer twice about it. The first time, they replaced the tensioner pulley and mechanism, the second, they replacted the vibration damper. Neither of these has fixed it.

I notice it's more pronounced with the A/C on. It does not appear that RPM's are dropping too low, but that's the only thing I can think of. I've just sort of resigned myself to living with it as the dealer near me has not actually fixed any of the things I have brought the car in for.

 

[yellow_2002_germany]

Are your cars automatics or manuals? The manual trannys do have a "buzzing" sound when moving from a standing start or accelerating from a very slow speed.

With manuals this noise is normal according to the driver's orientation video included with the car. c4c5specialist stated in another post what the exact reason for the noise was.

 

[AZMike]

Mine's an auto.

 

[yellow_2002_germany]

I can't help you with the auto trannys.

Sounds like a question for c4c5specialist.

 

[JCR]

This was a common problem that was thought to be rectified by redesigning the alternator. This new design would eliminate the rumble for a time. The rumble will come back. I noticed however that my Idle is around 525 when the rumble ocurrs. When I increase idle up to 550/575. the rumble disappears. I wish I knew someone who could re-program my PCM to raise up the idle. This is a sure fix at least in my case (automatic trans.)

 

[wrrvette]

This has been a problem that Chevy has known about since 1997.
If you go to the NHSTA web site you will see a Chevy Service Bulletin on a rumble noise when making parking moves. The cure is to have the belt tensioner and generator replaced. I had this problem but was way passed warranty and Chevy would not replace it. It doesn't hurt anything and my rumble finally went away.

 

[AZMike]

The funny thing is that the dealer did replace the tensioner assembly and pulley on mine, and it still does it. It seems a little less extreme after the fix.

I'm thinking it has to do more with engine idle speed as it only really is noticable with the A/C on. I guess I'll really have to watch the tach when it happens again to see if the idle drops too low.

 

[wrrvette]

The tensioner alone is not the cure.