Drive Train Vibrations (W123)
 

I am trying to narrow the choices of where to look for some really odd vibrations coming from my 84 300D and I thought I would enlist your collective help.

At idle (750 +/-) the engine is a bit shaky - BUT when the A/C compressor engages the car really starts to do a jig. It feels like the car is gyrating from under the front seats and she moves a bit up and down in a circular motion. Smoothes out to it regular idle shake when the A/C compressor disengages. Ideas?????
:confused:

I have an 83 300D with the exact same problem:
http://www.peachparts.com/shopforum/showthread.php?t=126833

You can see what I've had done to the car (all suggested possible fixes from the research I've done) with some results, especially the valve adjustment, but nothing has fixed the problem thusfar.

Good luck.

Replace both front motor mounts.

Have a great day,

What has already been done
 

Motor Mounts are Newish
Valves Adjusted
New A/C compressor
Belts

What is "Newish?" Have they been changed since the problem started and did the problem go away after replacing them? How long ago were they replaced?

Vibrations are among the most if not THE most difficult problems to troubleshoot via the internet.

Good luck,

They look lioke they are fairly new - perhaps the PO replaced them. I have a pair here I will put on to see if that does the trick.

just read today
 

I don't know if this will help but one of the posts i read this morning was about a guy who had the shakes like you describe and he changed the engine shocks located near/on the motor mounts - usually only for dampening when you shut the engine off but it fixed his problem.

this is the post http://www.peachparts.com/shopforum/showthread.php?t=43751&highlight=engine+shocks

Check the dampeners...
Check the transmission mount

I'd also check the IDLE SPEED. Did you check timing chain stretch when doing the valve adjustment? Does it seem sluggish off idle? Or does it seem peppy? If the timing is off by a good bit, that always seemed to make my cars run rougher- especially when they were less than 1/4 tank.

The chain is good and was checked at valve adjust (last 2000 mi). the car is like a rocket ship off the line! . I will continue to trouble shoot. Thanks!