SL320 VIBRATION IN COLD IDLE & GEAR IN 'D'

[detailas]

Greetings everybody,

I am new to the forum and I would appreciate some help with a problem I have with my 1995 W129 SL320 (abt 100,000 miles).

Last week I had the catalytic converter and the muffler changed - all was done in official MB dealer.

Since then, whenever I start the car, lock the gear in 'D' to drive away, engine idling and I am still on the brakes, I feel a vibration / buzzing, which goes away after I rev up and drive away.

The vibr / buzz is bit embarassing so after I drive away from the house and I stop at the 1st/2nd red traffic light (while engine is still cold) I prefer to shift in 'N' (no vibration then) and wait for the green light, than to feel the uncomfortable vibration. After the engine is warmed up (2-3 miles driving) - no unpleasant sounds, etc - all is normal.

Above symptoms disappear when:

-the car is either warmed up (no problem when idling in 'D' plus brakes) -or-
-when although still cold, the revs exceed abt 1200.

This happens only in 'D' position and not in 'P' or 'N', 'R' (as one would expect) - and only when the car is cold.

Any ideas please?

++

[BENZ TEK]

Check for proper exhaust clearance. I bet a heat shield is rubbing the cat. The reason you probally only hear it in drive is because the motor rocks in opposite directions from drive to reverse. So in drive it leans toward the shield and in reverse it leans away.