A couple of concern on my car

[hitbyastick]

Hello,
One of the things my 84 300SD does is shake a whole bunch once it's warmed up at idle. If I put it into neutral of park it get's a little better because the RPMs go up a hair. As soon as I get on the throttle, even if only a little and the RPMs increase, it smoothes out very nicely. The engine shocks have never been renewed, and I'm not sure about the engine mounts either. Could this be the problem?

There's a clunk of the rear suspension when I go over rough road. I'm assuming it's some bushings. The suspension itself seems very good.

There is some vibration from the front of the car at speeds. It is not RPM related or anything, and I doubt it's the drive train. Might it be an imbalance in the wheel? Or something to do with the engine shocks/mounts too?

And last but not least, where can I find
-a manual (for repairing, like chilton or some others), and do you recommend it. I do a ton of work on cars and I'm inclined to do everything myself, but just for references?
-a good mercedes mechanic, just in case, in the san francisco bay area.

Thanks a lot
-Christoph

[darius]

Christoph,

"One of the things my 84 300SD does is shake a whole bunch once it's warmed up at idle... Could this be the problem?"

Shaking in a diesel yields myriad possibilities. A good mechanic familiar with MB diesels will be able to diagnose with ease.

"There's a clunk of the rear suspension when I go over rough road. I'm assuming it's some bushings. The suspension itself seems very good."

Usually a simple fix. Suspension rubber wears out.

"There is some vibration from the front of the car at speeds..."

Could be any of the things you listed...a tie rod end or a pittman arm. A simple check for a trained independent wrench.

"And last but not least, where can I find -a manual (for repairing, like chilton or some others), and do you recommend it..."

Best choice for manual is to buy the factory CDs, which are sold on this website (I think the W126s are in stock). The factory CDs are the definitive manuals for working on these cars. There are even an couple of helpful computer indices out there, made by users, that supplement the CDs, making them easier to use.

"a good mercedes mechanic, just in case, in the san francisco bay area."

Can advise as to SF. However, everything you've described seems like a pretty normal fix for a car that age. Rubber wears out and bushings and mounts go bad. Rather than throw parts at it, why not spend the cash at an independent mechanic and have them disagnose precisely what is wrong. You can do the work yourself with the CD manual. M-Bs can be wallet killers if you just start tossing parts at them...of course, conversely, at this age, replacing all the mounts on the car and llots of the suspension rubber on principle is not a bad idea. If you just get the manual and start replacing, there is a lot of rubber to start renewing. That W126 has 2 motor mounts, a tranny mount, at least one rear subframe mount and a differential mount.


Good Luck,

Darius