PeachParts Mercedes-Benz Forum - View Single Post - need help from my diesel support group.....

JimSmith · #9 03-13-2002, 11:06 PM

Ryan,

Don't get discouraged, and pick the jobs to work on one at a time, in the order of how important they are to you. Of all the things you described, the idle control issue and the sagging rear are the only ones that sound like out of the ordinary, and the sagging rear is not really that much out of the ordinary. But it should be fixed.

All the cars I have actually torn into had a pretty much manually adjustable idle control means, with a knob on the dash. My new
Diesel does not have this feature and I suppose yours doesn't either. So, I am not too clued in on how the idle is regulated on your car, so I won't volunteer any advice on that matter.

The rear shock replacement job is pretty simple and straightforward. I jack the car up and put it on jack stands, and use a hydraulic jack to manipulate the position of the trailing arm/suspension. On a W123 model, the rear seat should be taken out to get access to the top of the shock. This is likely the same on the car you have.

Before I start taking the old shocks out, I make sure the suspension is not hanging all the way down. To do this I use the hydraulic jack on the side I am working to push the wheel a few inches up against the springs. This keeps the load of the springs pushing against the suspension off the nuts at the top of the shock.

The upper connection has two, 17mm nuts (that is what they were last time I did this), one that locks the other. Once these are off, a large washer and rubber donut should come off. The lower end has two similar sized nuts or on some models, bolts, that fasten the lower end of the shock to the suspension. Once the fasteners are off, I jack up the suspension a few inches further, then hold the shock with my hand in that position while I let the hydraulic jack down until the top of the shock comes out of its mounting hole. Then you may have to compress it completely to fish it out of the location.

A worn out shock will not be hard to hold in the compressed position or compress it more by hand. The worn shock has relatively little force left to push the shock out to its full length since the gas pressure has bled off as the shock failed.

This is not the case with the new shock. They come with a tie wrap holding them in the compressed position so you don't have to do it yourself. I have tried taking the tie wrap off before I put the shock into the space in the suspension, and this is not the way to do it.

You are better off getting it in there, and, as the last thing before you locate the top connection in its final position, take the tie wrap off.

I use the hydraulic jack to locate the suspension where I want it for the installation sequence as well. I extend the suspension to its maximum travel while putting the shock into position and installing the lower fasteners. I also try to get the most available space for pulling the tie wrap off, but with the tip of the shock in the mount hole so it goes through once the tie wrap is off. This means you jack the suspension up a little to get things lined up for success, and pull the tie wrap off.

Before you put the new shock in, you will want to install the lower rubber donut and washer on it, then go through the steps of feeding it into position and pulling the tie wrap off. Once located the rest of the job is putting the outer rubber donut on, the last washer, and then tightening the fasteners. I have always tightened the upper ones down until they do not go any further, but I have read on one of these forum threads that this is not always correct.

Depending on how long you have gone without a shock change the lower fasteners may be frozen by corrosion. I would recommend a good soak in a penetrating fluid of your choice as I have had to drill out the existing fasteners and install a bolt and nut making the job a long pain in the rear.

I hope all this helps, and is applicable to your vehicle. Good Luck, Jim