Frame Rust at Thrust Rod Mounts - Advice / Parts Needed
 

My 1991 350SD was making clunking sounds when I turned the wheel, I looked underneath and juggled things around and didn't see anything. I took it to a shop and they found nothing. I had them check the alignment and it was OK.

Then it started making clunking sounds when I slowed down to stop and released the brakes. I got underneath and took off all of the under engine cover panels. The damage was hidden by the under engine covers.

I was horrified when with what I saw. I think it is the thust rod mounts on the drivers side (the bar goes underneath the engine and has a bar that goes forward to the control arm are broken in two places.

There is a lot of rust and when I inspected the other side it isn't yet broken, but there is some rust there too, and it should be repaired.

Some pictures are attached.

Obviously it is going to require some welding to fix it, but I need some advice here.

Have any of you run across this before? How did you fix it?

BTW: Other than this the car is in excellent condition. The engine has 30K miles on a rebuild with updated rods, new turbo, looks new, etc..

:(

Are you sure you are speaking of where the Swaybar Mounts?
The pictures show the Thrust Rod.

If there is no special repair panels made it would be nice if you were able to go to a Junk Yard and cut oversized sections of what you need so they could be welded in.

But, that brings up the issues of dimensions.

Body Shops have books that have points of measurement and dimensions so that can try to restore things back to normal. Without Having another Car to take measurements from I am not sure how that could be done.

Wow. Horrified is what I would be as well. That is some serious damage in an important and hard to repair place. I would seek out a reputable shop with good insurance to get it repaired. If you cannot find a shop with good insurance and a good rep to do it,......keep looking.

Good luck.

Probably should not drive it until repaired.

I'd also have a good look at the upper sway bar mounts to look for damage there.

This is the sort of damage that puts older cars in the yard in many cases.

Body shop, good idea.
 

There is a local body shop that may be able to do the job. I will check with them.

Has anyone else dealt with this? I want to gather as much information as I can, and since I haven't done any welding since high school I don't think I will be doing this myself.

I worry about cutting pieces out of another car because I don't know how strong those pieces will be.

edit: nvm read your last post.

What do you mean?

Has anyone cut out those pieces to patch into a another car?

I had exactly the same problem on my 91 SDL. Drivers side gone, passengers side still there.

I had a new bracket made for the guide rod mount. The backing plate that attached to the "frame" (outlined in red) I had made to extend down the "frame" to well beyond the rust (that detail is not shown in the red outline). It was also made to rest against the corner where the "frame" meets the floor pan so the forces acting on the guide rod would be stopped there and the new bracket would not move when it use.

The piece of metal from the car that was still bolted to the top of the guide rod mount (best seen in the first photo) has a locating ring that holds the mount in place. This piece of metal was still good and was cleaned up and welded to the bottom of the new bracket (outlined in green).

I went to the machine shop with a cardboard mock-up of the bracket. The new bracket cost me $58. ( Actually, I traded a computer monitor for it. ) I think they used 3/16 steel.

I cut/chiseled what was left of the original mounting bracket off the "frame" rail.

The new bracket was bolted to the guide rod mount and guide rod mount and the cross piece to the other side's guide rod mount were reinstalled. Then with everything located where it was supposed to be, hard bolts were used to mount the new bracket to the "frame". The inside of the "frame" rail had no rust.

Then I got an alignment.

That was about 25k miles ago.

If you do not wish to go to all this expense and trouble, I will gladly give you $50 for your car as is.

If that area looks like that, have you inspected the rest of the car underneath? :eek:

Here is why I want to save it.
 

Here is a picture of my car in the parking lot next to a much newer S-class.

It is actually a nice looking car.

I have inspected the rest of the car underneath, and I did fix some surface rust. The problem with this area is that it was completely hidden under the under-engine cover.

Do you have a picture of it now?

Do you still have those cardboard cutouts?

Come on, if I make it too easy you won't sell me your car.

Cardboard is gone. I don't have an "after" photo. The wheel hasn't been off since I made the repair.

Maybe you can just turn the wheel and take a picture. My pictures were with the wheels on!

Photo