Hello All,

My '78 W123 has a Steering Box that is seeping fluid. I'm almost positive that the leak is from failing O-rings on the Pitman Shaft Bearing Cap, and not the Shaft Seal. Since the Steering Box is fine in all other aspects, it doesn't need a complete rebuild.

I am wondering if I can keep the O-ring replacement job to a minimum, and save myself some time and aggravation, and do the fix without dropping the Gearbox? Short-cut, perhaps.

With the Steering Box still in the car, this would be my plan of attack:
1) Pull Pitman Arm
2) Drain oil via Box Drain Plug
3) Remove 4 bolts holding Output Shaft Cap
4) Remove Cap
5) Replace 3 (I believe?) O-rings.
6) Reinstall in reverse order
7) Fill Reservoir with Fluid
8) Bleed system

I have been reading and rereading some old threads from David Petryk, Stretch, & others so as to gain some knowledge. I see no reason why my plan wouldn't work. Please correct me if I am in error. Wouldn't be the first time .......

Thanks Much,
MM

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Gute Fahrt

Dropping the box really is not that much work and the job is MUCH easier on the bench. Then you can change all the seals and not kick yourself later on. Just watch out as that box is heavy so plan accordingly.

Appreciate your thought. It seems to me that those 4 Output Shaft Cap bolts can come out just as easy, if not easier, with the Box still in the vehicle. The O-rings are installed to the Cap. What can be easier than that! Those bolts are just staring me right in the face with easy access from beneath.

I've R&Red steering gears before. Not difficult, just a PITA. Yes, heavy. If the Box ever needs a complete overhaul, I' would most likely send if out to someone who has all the special tools.

For the time being, my original question slightly reworded ... will my method in the first post work?

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Gute Fahrt

done the way you posted it many times in the shop. but, i had a lift. never done that on my back.

Hi PF,

Thanks for taking the time to reply. You gave me the reassurance I was looking for. Floor Stands and a Creeper aren't the easiest way to do it, but I've managed to replace complete exhaust systems, brake & fuel lines, front end steering components, and plenty more, flat on my back. The garage ceiling just isn't high enuf for a lift.

Just ordered PN# 126-460-00-61 Overhaul Seal Kit and a new Pitman Arm Nut PN# 001-990-54-51. Now that the Climate Control Valve and the York Compressor are repaired, time for the Steering Box.

MM

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Gute Fahrt

Pelican has a great article detailing the steering system. Although they don't touch on the steering box much there's great tips on the job overall including the drag links and idler arms.

https://www.pelicanparts.com/techarticles/Mercedes-W123/124-SUSPEN-Steering_Rebuild/124-SUSPEN-Steering_Rebuild.htm

Thanks Matt,


Good reference for anyone reading this thread. In my case ... been there, done that! With the right tools and reference (torques, etc.), an easy job, IMHO.



MM

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Gute Fahrt

All,


Just to follow-up .... the job was completed without any problems. For future reference for anyone with a leaking BOTTOM end steering gear (on a W123/ M110), the three Oring seals can be replaced without dropping the whole steering gear. While taking a bit of additional time to disconnect the linkage from the Pitman arm, it avoids damaging the tie rod and drag link ball joints. Make sure you have a good ball joint separator, Pitman arm puller, and impact gun.

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Gute Fahrt

I apologize for being late to the party.

I recondition these boxes on a regular basis, so I'd keep my eye on the box. Once the seals start breaking down (especially at this age) they'll continue to break down. That doesn't mean you might not get years more service without trouble, but it doesn't guarantee the other seals might not be failing.


Whatever you do, don't use fluid with stop leak additives in it. Its a short term fix that will weaken the seals.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Yessir,


I agree 100% on the 'snake oil' quick fix. Read that, long term trouble with a 'polluted' system. I replaced about a dozen or more seals from the front main crank through the diff, and then some scattered here and there, over the last couple of years. Funny (well maybe not!). how a $.50 part can so sooooooo many hours of labor.



Drips can drive me nuts!

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Gute Fahrt