Rattle

[JMI]

1989 535i Automatic

This has been happening off and on for a year or so. If I stop the car and leave it in drive (D) holding it stopped with the foot brake, as for example while waiting in a long line, sometimes as I pull away I get a metallic sort of rythmic rattle that sounds like it is coming from the drive train. It increases with the car speed. If I stop and shut off the engine and restart it goes away. It only happens after a long idle in gear with the brake on.

Any ideas what the source could be?

TIA

Jim

[ahlem]

Center bearing getting preloaded and unloading? Had an Audi once that did something similar until I changed the center bearing. Check the guibo also. Motor mounts in good shape?

[Dave M]

Hmm, good question. Best of luck.

[JMI]

Center bearing getting preloaded and unloading? Had an Audi once that did something similar until I changed the center bearing. Check the guibo also. Motor mounts in good shape?
Don't believe the car has a "guibo". The fact that the noise is so intermittent has me baffled. I usually drive the car alone and the noise does not happen at idle speed but I have to start moving from a stop before I hear it. so it is kind of hard to check it on the fly.
Thanks for the reply.

Jim

[whiskychaser]

Exhaust touching something or a loose mounting?

[JMI]

Exhaust touching something or a loose mounting?

That sounds plausible, thanks.

[JMI]

To close out the thread...

The noise come more often and louder. Don't know the order of failure but the forward joint of the drive shaft that attaches to tranny output was very stiff, the center bearing was totally shot as well as the tranny mounts.
Replaced them all a few weeks ago.

Car runs much smoother ;)

Jim