Steering box interchangabilty? - PeachParts Mercedes-Benz Forum

eatont9999 · #1 10-16-2012, 01:43 PM

Hi all,

My steering wheel has had some abnormal play in it since I bought the 300SD. It even has play in it when the engine is off. I have recently noticed a slow leak coming from somewhere on the steering box. Mind you I have re-sealed the PS pump and there are no leaks on it or around the hoses. I washed the engine bay a few times this summer, so it is clean.

I plan to go to the junk yard this weekend and pull a steering box from a W126. The gas powered cars usually have less miles and potentially less wear on the steering box. Would the box from a gas car work in my 300SD? Any particular year models that would also work?

Thanks!

Stretch · #2 10-16-2012, 02:00 PM

I haven't checked the W126 FSM on this but the W123 FSM details loads of information of the variations of the same theme - there are differences in the Pitman arm too that might be of importance.

(Pitman arm removal can be a pain in the arse)

My first stop would be the FSM - most of the boxes are marked with Ys and Xs to tell you what they do.

If you haven't seen it this thread might encourage you to check the FSM!

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

eatont9999 · #3 10-16-2012, 05:18 PM

According to a guy who rebuilds them for a living, all W126 boxes are the same. Now, that doesn't mean the pitman arms are the same. I really don't want to mess with pulling one of those damn things off! Worst case scenario, I have someone else do it.

Will a W124 Steering Box Fit the W126? - Benzworld.org - Mercedes-Benz Discussion Forum

eatont9999 · #4 10-16-2012, 05:22 PM

So, I guess I could look for the lowest mileage W126 I can find. The yard down the street might still have that 380SE that I pulled a bunch of interior parts from. It was in a pretty bad front-end collision so I can't say the steering box or pitman arm have not been bent without looking at it again. At least they sold the engine, so that is out of the way.

eatont9999 · #5 10-18-2012, 12:20 PM

I forgot to mention that with the engine off and the ignition on, if I turn the wheel to the left, it makes a clunking sound from the left fender area. I'm not turning the wheel hard, just going back and forth within the play it has. From what I have read, clunking is not a good sign. The tie rods are new, guide rod bushing on that side needs to be replaced but with my hand on it, I don't feel the clunking coming from there.

JamesDean · #6 10-18-2012, 12:25 PM

I wouldn't put much stock in low mileage. My one 300SD only has 144k on it and the steering box is absolute ****. It has a huge notch in the middle when slop is removed via the bolt. I'm going to EVENTUALLY buy it a nice rebuilt unit.

Stretch · #7 10-18-2012, 12:58 PM

Chasing suspension clunks can be really difficult - sometimes when you think it is coming from the right it is coming from the left - the best way of fault finding that I know of is to put both front wheels on skid plates and then try different situations...

...I'll add in the ususal warning about cars being surprisingly mobile on skid plates though!

Have you checked the idler arm?

martureo · #8 10-18-2012, 03:16 PM

Quote:

Originally Posted by eatont9999

Hi all,

My steering wheel has had some abnormal play in it since I bought the 300SD. It even has play in it when the engine is off. I have recently noticed a slow leak coming from somewhere on the steering box. Mind you I have re-sealed the PS pump and there are no leaks on it or around the hoses. I washed the engine bay a few times this summer, so it is clean.

I plan to go to the junk yard this weekend and pull a steering box from a W126. The gas powered cars usually have less miles and potentially less wear on the steering box. Would the box from a gas car work in my 300SD? Any particular year models that would also work?

Thanks!

Yes, there is a difference between some w126 boxes, but unless you're taking one apart you wouldn't be able to tell.

If you find yourself in the midst of plenty of w123 boxes you could use one of those. The only differences would be the lack of a play compensation device and the different pitman arm.

Each power steering box (123/126) has two generations, but like I said you probably wouldn't be able to tell the difference.

And to burst your bubble, I have not yet found a way to guage play in a box without it being pressurized (i.e. running on a car). I've tried low mileage cars and still found them to have plenty of play. I've also tried grabbing boxes which feel tight but end up having play when you drive on them.

I'd be happy to rebuild a box for you (a side business of mine), but I have a rebuilt w126 box sitting on my shelf right now. It's got more play than I like so I'm selling it cheap for $80.

martureo · #9 10-18-2012, 03:19 PM

Quote:

Originally Posted by eatont9999

I forgot to mention that with the engine off and the ignition on, if I turn the wheel to the left, it makes a clunking sound from the left fender area. I'm not turning the wheel hard, just going back and forth within the play it has. From what I have read, clunking is not a good sign. The tie rods are new, guide rod bushing on that side needs to be replaced but with my hand on it, I don't feel the clunking coming from there.

Not as familiar with the front suspension of w126's as the w123's, but the guide rod ball joint could be popping out repeatedly.

eatont9999 · #10 10-18-2012, 03:26 PM

Quote:

Originally Posted by Army

Chasing suspension clunks can be really difficult - sometimes when you think it is coming from the right it is coming from the left - the best way of fault finding that I know of is to put both front wheels on skid plates and then try different situations...

...I'll add in the ususal warning about cars being surprisingly mobile on skid plates though!

Have you checked the idler arm?

You aren't kidding about finding suspension and steering noises. It is like chasing your tail in circles.

When I replaced the tie rods, the idler arm seemed to be fine, so I didn't install the bushing kit for it.

eatont9999 · #11 10-18-2012, 03:31 PM

Quote:

Originally Posted by martureo

Not as familiar with the front suspension of w126's as the w123's, but the guide rod ball joint could be popping out repeatedly.

It may be the guide rod ball. It needs to be replaced. I have a spare bearing bracket that I am working on rebuilding with new parts. It is just a PITA to get the bushings out, so today I am going to run over to HF tools and get some things that should make it easier on me.

Whiskeydan · #12 10-18-2012, 10:46 PM

Quote:

Originally Posted by eatont9999

It may be the guide rod ball. It needs to be replaced. I have a spare bearing bracket that I am working on rebuilding with new parts. It is just a PITA to get the bushings out, so today I am going to run over to HF tools and get some things that should make it easier on me.

BFH is the tool to remove the guide rod bushing on a W126.

Get a large hose clamp to squeeze it down a bit when installing it. Makes going in a lot easier. Make sure the drain groove is on the bottom of the bracket.

I have a diy thread on here somewhere a few yrs ago with pics. Search...

Go get a Craftsman "ratcheting open end" to turn that rod. Makes life much easier.

eatont9999 · #13 10-19-2012, 11:45 AM

The spare guide rod bracket have came from an 82 300SD that had a lot of rust. It was clearly a northern car that someone brought down here and scrapped at PNP. I got the two side bushings out with a set of 6" gear pullers. That was easy.

I have been beating on this thing for the past 3 days with a 3lb sledge and it is not budging. I added a second treatment of penetrating oil last night. Air impact hammer on the ball socket does nothing, either. I am now trying to use the air hammer to push in the tabs on the back of the bushing to break some tension. I might try to find a way to get the gear puller on this thing.

eatont9999 · #14 10-23-2012, 04:48 PM

To elaborate on the bearing bracket:
http://www.peachparts.com/shopforum/diesel-discussion/327912-w126-bearing-bracket-busing-mount-removal-easy-way.html#post3034258

Removing the steering box is a little bit easier when the engine is missing such as was my case. The main obstacle I ran into when removing the box was the bolts in the fender are hard to get to. I couldn't get enough torque on the bolts with a regular ratchet and there was not enough room to get a breaker bar in there. The solution for me was to take two 12" extensions, attach them to my breaker bar and socket and use the breaker bar outside of the fender well to loosen the bolts. If you have an impact wrench handy, it would probably do the job as well.

The next hardest part was popping off the tie rods but that really isn't hard to do. Just use a screw type puller so you don't damage the tie rod boots.

pwjeep · #15 10-23-2012, 07:46 PM

The W123 and W126 steering boxes are not interchangeable. The bolts / holes do not line up on the sill. We tried to put a W126 box into my W123... The bolts / holes were further apart and thus didn't work. We eventually found another box that was good.