PeachParts Mercedes-Benz Forum - Steering Problems on 87 300td

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Steering Problems on 87 300td

I have recently rebuilt the suspension of my 1987 300td. I am not a mechanic but through reading this board was able to accomplish the job including resealing the tandem pump, resealing the steering pump, and getting the self leveling system to work. When I finished I had a problem where the car felt bouncy. Not like the pods were bad but it bounced around more then it should. I finally diagnosed it as air in the hydraulic system. I was able to fix that by having my son and three of his friends bounce on the rear bumper of the car while I held the throttle to 2200 rpm. That bounce is now gone.

I have another problem that I can not diagnose. When I turn the car hard to the right the the steering kind of locks in place as if it has come hard against a stop and doesn't "bounce" back to the center. It doesn't take any force on the wheel to get the steering off of the "stop" but I know it is not right. I was careful to measure the pitman arm and have it back in the right place to on the steering pump. I am wondering if 1) the pitman arm may need to be adjusted in or out on the shaft of the steering pump or 2) when replacing the seals in the power steering pump could I have incorrectly aligned the gears inside the pump. The mark on the pitman arm does align with the mark on the power steering pump. Any help with this would be appreciated.

I took the car into the best independent mechanic that I know of (he goes to Germany on vacation and does research for Mercedes in their vaults) and he could not diagnose the hard "stop" on the steering.

Now that the air in the hydraulics is cleared up the car drives much better but I can now feel a different problem. When making a turn on a windy road and the road is flat the car feels fine. When there is a bump on the road during the turn the front end bounces a little and the car doesn't track correctly. I am not sure if this happens on both right and left turns or just on right turns. It is very subtle but unnerving.

Is there anyone who can help me with these problems?

I will keep my eye on this problem as i have the same thing on my 87 wagon when you go fully to the stop on the steering it does not self return! However since it turns back with normal pressure on the steering wheel i never gave it much thought.Maybe we will hear from some of the many other 87TD owners here. Don

I recently had this problem (not self-centering) on my 91 300D. I had all sorts of suggestions, including alignment and steering damper....it was very frustrating In my case, it turned out to be bad ball joints. Though there were neither loose nor squeaking, they were in fact bad. As a safety precaution if nothing else, if your ball joints have never been replaced, replace them.

Anyway, either your alignment is off or something is binding, preventing the steering from self-centering.

I replied to this post but I had all the text inside the quote so perhaps that is why it got lost.

Quote:

Originally Posted by sixto (Post 2856560)

We should get our terms straight. To most folks here, the steering pump is the device driven by the engine serpentine belt that delivers pressure to assist in steering. In the case of your TD, the steering pump is in tandem with the pump that provides pressure to the SLS. The device that takes a signal from the steering wheel and is assisted by the steering pump is the steering gearbox or just steering box. The pitman arm attaches to the steering box.
[COLOR="rgb(65, 105, 225)"]Thanks for the info. I was confused in my terminology. I rebuilt opened up both the tandem pump and the steering box. I had installed the same steering Box that was in the car and then when I tested it there was a massive leak when I turned the car to hard right. I opened up that steering box and found a a flaw in the metal of the casing. I then took out the steering box from my parts car and installed it. I don't remember whether I opened up the second steering box or not.[/COLOR]

I have difficulty understanding the problem you describe but it sounds like you reach a point in right turns that the steering linkage doesn't naturally return to straight ahead when you release the steering wheel.
That is exactly the problem that I am havingThat's unusual. My questions at this point:

1) Did you touch anything in the steering linkage? Tie rods, center link, idler arm, etc.?
[COLOR="rgb(65, 105, 225)"]I replaced all of the above parts. Pretty much everything in the front end[/COLOR]

2) How far into the steering box did you go? Did you replace the pitman arm shaft seal and call it a day, or did you take it apart completely and set preload to the inch-pounds specifications?
[COLOR="rgb(65, 105, 225)"]I took the steering box apart[/COLOR] If you removed the steering box from the car, did you use locking compound on the bolts (which you're not supposed to reuse)? Is it still firmly attached to the frame?

3) Did you do any work to the front suspension that might have altered camber, caster or toe settings? [COLOR="rgb(65, 105, 225)"]Yes I did but then took the car in to have it aligned.[/COLOR]

4) Did you bleed the power steering system? [COLOR="rgb(65, 105, 225)"]As I remember the power steering bleeding was a pretty simple cruise down the driveway to "berp" the air out. [/COLOR]

5) What motivated you to touch the steering system in the first place? What problem were you addressing? [COLOR="rgb(65, 105, 225)"]I had multiple problems. I had a leak in the steering box which I couldn't find because it only leaked when the wheel was turned hard right. I thought the leak was coming off of the engine somewhere but I was wrong. Also there was a problem with the tie rods. The car would clunk every time we turned. I don't remember if it was both ways or just to the right. I replaced all of the front end bushing and tie rods. Then the pods went bad and the car was bouncing. When I fixed that I found that the tandem pump wasn't working so I resealed that and it works fine now. I also had to clean the SLS valve. The SLS works now but may need a final adjustment. I then replaced the rear end suspension arms bushings tie rods etc. Now I am down to trying to figure out this final problem ( I hope) [/COLOR]

Having asked all that, someone will come along and suggest you flip some switch to make it right :)

Sixto
87 300D

Thanks for the questions Sixto hopefully someone will have the answers.

Quote:

Originally Posted by shertex (Post 2856817)

Thanks I have had the car aligned and have replaced all of the tie rods and ball joints. Unless something was bad from the factory parts ( a possibility) I don't think that it is a bad ball joint. My latest guess is the steering box. I have one on the bench that has a flaw. I am going to study it and see if I can figure out what it is that causes the steering to "bounce back" If anyone knows them intimately I would love to hear about how the work.

Quote:

Originally Posted by Seadawg33 (Post 2857797)

Call C&M Hydraulics 888.407.6900. MB steering box experts. Extremely helpful.

I'd go and look at the control valve. As far as I know that's the only thing that could be providing the bounce you want. As you have seen from the W123 steering box there's no return spring in there - I think the W124 steering box is of a similar breed.

http://www.startekinfo.com/StarTek/outside/12264/disc_2/Program/Chassis/46-0238.pdf

Found from

Mercedes-Benz Model 124 Service Manual Library

I think you'll have to remove the steering box to access it though. Keep on looking through those online PDFs and you'll find the FSM chapter to help you with that.

This thread by Army is very well presented. It'll bring a tear to your eye :)

http://www.peachparts.com/shopforum/diesel-discussion/303379-what-feeling-will-properly-adjusted-w123-w116-w126-power-steering-box.html

Which brings up another question - when you installed the steering box and had the wheels aligned, did you use the centering tool? Not many alignment shops are aware that MB requires this tool.

Sixto
87 300D

Thanks Army and Sixto. I have the original steering box ( with the flaw) on the bench right now. I will have a look at it and see if I can replace the control valve. I got a new set of sockets for Christmas so this will be a nice way to break in my new toy.

keep in mind, the 87 has the strut bearings up top, they could be damaged, or old, and keep the steering from returning as well! Mine squeak when I turn... so I know I'll need a set soon...

VS Tech thanks for that piece of information. The timing is great. I just heard the front end squeaking as I went over some speed bumps. The speed bumps were in the tire shop where the mechanic said I should look into changing my front struts.