Yes, it's 12 and 13 in the diagram. They're the inner and outer piston seals. I don't have the transmission manual available here at this time (it's on a computer that is down at the moment) but I remember something about noise in reverse possibly being caused by the B3 piston having to move further than normal and contacting rotating parts of the transmission. This is normally due to excessive B3 clutch wear, but could also be an assembly error. It happens to the best of us when working on transmissions

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Erich Loepke
2010 Ford Focus
Currently Benz-less

Thanks very much for these extremely detailed responses. However, if the problem was originally caused by worn B3 clutches, as other threads led me to believe, the new clutches should have corrected it.

And, imo, its unlikely that the problem was caused by an assembly error during the rebuilding, because the transmission has the same problem it had before I had it rebuilt.

As for the possibility that the problem was originally caused by leaking inner and/or outer piston seals, I just assumed that those would have also been replaced as part of the rebuilding. But if they weren't, and were in fact leaking, that could account for the problem.

In any event, they still have the car, but I can't get in touch with them because of the snow that just hit Philly. However, I'll ask them about these things when I do get in touch with them.

In the mean time, if anybody has any other ideas as to what may be causing my problem, they, too, would be greatly appreciated.

The seals in question are illustrated somewhat in this guide:

http://www.w124-zone.com/articles.php?article_id=21

You can find this passage about 60% through the writeup...the piston is the picture just below this quote:
There's a huge o-ring seal around it and a lip seal in the center of it. Five pictures down from it you can see it's backside, without the seals on it.

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

Thank you. I see what you're talking about but, since I wasn't there when they rebuilt the tranny, I don't know what they did or didn't replace. OTOH, after talking a bit to the bench-man who actually rebuilt it, I came away with the impression that he had rebuilt many of these, and knew exactly how to do it. So, that's why I left it there.

I'm just hoping that they'll take the time to remove it, and see why it's still doing what it was doing when I brought it in, and, hopefully, we won't have to get into a dispute as to whether it's behaving normally or not.

Let me say again that I really appreciate the concern you and other very knowledgeable people have shown me here. These boards have obviously made it so much easier for people to get good info about these things than ever before, and I can't imagine what I would have done without this one .

Just a suggestion fwiw. If on going back to check on the vehicle, and it is still is not correct or to your liking. You could make a ploy to get your money back, because of your dissatisfaction. If they are like your impression of them has been, this should no problem. If they hedge on it, you might deal with them on getting it correctly else where, and they refund the monies it took to make it right. Then you can move on from there one way or the other.

Thanks for the suggestion, but it won't be necessary since I haven't paid them yet.

In addition, after taking the tranny out, disassembling it, and getting advice from someone who evidently knows even more about these trannies than they do, they've concluded that it is what I think the owner called a "regulation" problem caused by a leak in a valve or seal in the valve body(?) So they're going to replace the valve body.

I don't know what a valve body costs, but when I asked him, he led me to believe either that he's going to absorb it, or charge me what he paid for it. Any of you guys know how much a valve body costs wholesale, or whether my problem could have been caused by a leak in or failure of something in the valve body?

And thanks again for the help. You guys have been absolutely amazing.

A valve body problem is also possible, I guess, and that is much more correctable at this point without dropping the transmission. I have no idea what a valve body costs. Probably $1000 from Mercedes, $10 on ebay from somebody who has one lying around. Valve bodies are specific to applications- for example the valve bodies from a 722.315 diesel will work differently than the one in yours for a 380SL 722.3xx.

There's no reason to think it needs to be replaced rather than carefully cleaned, IMO and then the various upgrades can be done at the same time.
If it is disassembled, follow the instructions carefully ( especially about flipping it over when separating the halves- don't ask)

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

Thanks for the additional advice, but I think the rebuilder already opted to replace it with a rebuilt one, without giving me the option.

Last three questions, hopefully:

1) Should the transmission shop have been able to determine that the problem was in the valve body, rather than the B3 clutches, seals or pistons, when I described it to them, or they test drove and pressure tested it, as they were supposed to? (I hate to think that the problem could have been solved simply by replacing or rebuilding the valve body, rather than the whole transmission.)

2) Since the shop said that they had to rebuild the transmission to solve the problem, and they gave me a price that presumably included the labor and parts for doing that, should I now have to pay for them to buy and install the valve body?

3) AFAIK, this transmission hadn't had the fluid replaced until I did so app. 40-50k miles ago, when the transmission must have had app. 150k on it. Considering that some people have said that changing the fluid in such a transmission can create problems by removing varnish on seals and other parts, is it possible that the fluid change I performed ended up causing my problem? (I hate to think that it did.)

Thanks in advance for also answering these questions for me. You guys have been absolutely tremendous.

1) I really don't know . I for one, am not smart enough to positively diagnose something like this. I have only rebuilt one more of these than you have

But- did they fix it with the valve body change?

2) I would say no- you told them what the problem was up front, they offered to fix it via a rebuild. They didn't fix it as contracted.

3) Remotely possible, but I would have done the same thing.

Rick

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

The front pump most likely needs replacing. The whirr sound is the pump trying to keep the torque converter full.

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600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.

Daddi might be onto something....but of course....

This should be known already because they should have taken the front pump apart to REPLACE THE FRONT MAIN SEAL. Any repairshop who does not do this every time the 722.3 is removed is not the right person for the job.

Again, make sure the front pump has been resealed. It must be done and when it is done, the pump gears should be inspected since it is apart anyway.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

After having similar problems, and making a few phone calls to rebuilders (who all claim to be experts) I spoke to my MB dealership. They dont do rebuilds any more, they just order a genuine MB rebuilt and slap it in. I did not need a converter so $3100 for the trans, plus hoses, trans mount, and labor with 2 year 24 mo warranty

In reality, that's actually not too bad of a price for a completely rebuilt from MB....

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I haven't gotten my car back yet, know the cause of the problem, or the price of fixing it. So, the jury is still out as to whether rebuilding it was the way to go, and whether this shop knows what their doing.

When I do know the answers, I'll post them. That way those people who have been trying to help me answer these question, and others who may have the same questions, can benefit from my experience.

In the meantime, thanks for the recent responses.

Any news?

Happy ending?

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)