My steering gearbox blew the upper seal today (the one where the steering wheel shaft attaches). As soon as I heard the the pump making noise I topped it off and headed to an Auto Zone to pick up more fluid. Long story short, it took me almost 3 quarts of fluid to go 12 miles. I had to resort to turning off the engine at every red light and then eventually even turning it off and coasting after getting up to speed to keep from running the pump completely dry.

Is there any easy way to determine if I've done any damage to the pump?

I noticed that various suppliers sell a steering gear seal kit in addition to a rebuilt steering gearbox. Does anyone have first-hand experience with rebuilding the gearbox? The kit consists of about 17 o-rings, 2 oil seals and 7 circlips. Is this a fairly straight-forward repair that doesn't require any dedicated special tools? If so, I feel more than competent to do it myself, though of course any tips would be greatly appreciated.

When they're professionally rebuilt, do they typically do anything other than replace all the seals, clips and 0-rings?

Thanks.

Gary

Well, I'm still fiddling with this problem. I don't seem to be able to find a tool available to remove the left inner tie rod end from the Pitman arm. I've looked everywhere and found shops that normally carry it (like Performance Products), but they're out of stock till next week. Oh well, patience, they say, is a virtue. I guess they were never down to one car and had to shuttle the family to work and school twice a day.

Anyhow, I'm thinking of just replacing the upper and lower shaft seals, cleaning the innards by flushing it thoroughly and hoping for the best. It's the original steering box with about 144k mi. on it and seems to work just fine with little to no play in it. Has anyone tried replacing the seals and had luck with it long term?

Alternatively, has anyone tried rebuilding their box with the seal/o-ring/circlip kit? Is it difficult, or just tedious? How much time does it take, on average?

Thanks for any info.

Gary

I don't know how much help I will be but I will be resealing a steering box soon. The one I have is leaking at the seal above the pitman arm. First don't take the box apart you need a lot of special tools to rebuild one. Just fix the leak if you need to get inside either send it out or buy a rebuilt one. Remeber your life could be in danger if the box fails!!

As for removing the tie rod end and center link ends I used the fork tool you just hammer in the joint. It works well but will ruin the boot.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Hatterasguy,

I figured I would replace them both as long as I had the box out. From what I can figure out, the top seal is pretty easy. I'm hoping the bottom one is the same. I think it is. My Pitman arm appears to be snug, but not tight enough to require a hydraulic press to remove or replace it like some have mentioned, so that should make things a bit simpler. What's required to get at the bottom seal?

Do you know if there's any kind of pressure relief valve inside that can get plugged up causing it to blow out either of the seals, because it was a pretty catastrophic failure. That's why I'm hoping to find someone with experience in rebuilding one of these things so I don't miss anything. If it's nothing more than a seal, I can't see spending $400 dollars to replace the entire gearbox.

I resealed my gear box with a rebuild kit from Fastlane. I rented [free] from Auto Zone a puller that worked just fine. Just make sure you mark the box before removing it from the spline.

My dad got a pitman arm puller from work that I will use. Now that you mention it replacing the seal might be treating the symptom, why did it blow? I have never heard of a gearbox seal blowing like that!

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I know that for the 123. The power steering pump has a pressure control valve in the assembly. Not very difficult to remove and replace but I'm not sure on the 300E. Mercedes tends to use the same pumps on all the cars so if it is the same. The pressure regulating valve is in the pump.
The pump does provide a bit of pressure, I don't remember the PSI for it, check the manual, so it would cause a loss of fluid quite rapidly, but it doesa sound like you pressure regulator has gone bad for it to blow a seal in that fashion.
You will have to attach a pressure guage on the pump and measure it. Or just replace it.


Again my knowledge is for the 123.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

This maybe too obvious, but be sure and check and replace if necessary the power steering pump filter. Maybe its just never been replaced.

Also the fluid. I would only use Mercedes fluid. I have seen accelerated wear when using other types in older cars.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Replaced it about a year ago, though I'm going to replace it again just because (they're cheap insurance).

If the old seal developed a big crack, a lot of oil will flow out--not spray out with high pressure. There is not supposed to be any significant pressure against that seal. If there is/was and oil sprayed all over everything and not just drooled out--you have an internal seal failure.

Real easy to replace the input shaft seal and pitman shaft seal. Just be careful not to scratch the shaft or bore. Remember to paint mark the coupling to put it back - centered. My 560 sel had a 'set screw' in the steering box to center the internal gear exactly for removal/reinstallation correctly without guessing.

It was a large flow, not a spray, so that sounds encouraging. I finally got the gearbox out earlier today and took a quick look at the seal area, but there was nothing obvious to be seen from the outside. I'm assuming just the top and bottom covers have to be removed to replace the input and output seals, right?

I'm debating at this point whether to just replace the seals or put in a rebuilt box. This one has 144k miles on it and seemed to feel ok before the leak. There was very little, if any, perceptible play in the straight ahead position and some play at the extremes, but that doesn't really matter. My concern is whether a box with this mileage on it still has a long service life ahead of it with new seals installed, or whether I might end up with other problems in the next year or two. Conversely, I don't know if a rebuilt unit might have more mileage, and consequently more wear, on some of the critical internal parts.

Does anybody know with any certainty what actually gets replaced on these remanufactured units as a matter of course, besides seals and o-rings, of course, and what wearing parts may get left in?

Anyone have long term first-hand experience with a remanufactured gearbox? Or has anyone ever got one that was worse than the one you replaced in terms of steering feel or play?

Do they generally have useful warranty? How long?

Thanks,

Gary

What did you end up doing? I'm curious as I have removed the steering box in the 115. I will probably just reseal it, adjust the play and put it back.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6