B2 piston repair - PeachParts Mercedes-Benz Forum

quickster · #1 03-19-2017, 09:03 PM

My trans is weeping fluid thru the B2 piston cover. The o ring is most likely done so while I'm in there I might as well replace the piston itself. First off my trans is a 722.418. I'll be damned if I can find a replacement online. I even tried our sponsor here ,but nothing. Anyone know of a site where I can pick up a kit so I don't have to go to the dealer? Been looking and can't find one that matches. Thanks

Diesel911 · #2 03-19-2017, 10:09 PM

On the older models there is no kit so I doubt if there is one for yours. Parts are ordered separately.

Diesel911 · #3 03-19-2017, 10:32 PM

Someone else will have to verify this. But, I believe you might already have the most recently updated B2 Piston. If it does turn out you have the most recently updated piston it used to be you could purchase the outer Teflon seal separately.

That only leaves the Seal and the Bushing. The Bushing is also likely the updated white nylon one but it is inexpensive if you want to replace it.

And of course the cover O-ring.

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quickster · #4 03-19-2017, 10:35 PM

I've seen the o ring that I need for sale, but the piston itself, no. 1990 isn't that old!

quickster · #5 03-19-2017, 10:40 PM

Thanks. I hope that's the case.

Stretch · #6 03-20-2017, 06:27 AM

The dealership will probably be able to help with an individual seal

Diesel911 · #7 03-20-2017, 02:55 PM

If you look at a transmission manual the 722.3xx and the 722.4xx are in the same manual. That makes me think that the B2 Piston and related parts would be the same.

I was wishing someone who knows for sure would chime in.

ah-kay · #8 03-20-2017, 03:08 PM

These are the o-ring seal for the tranny. Verify part number before buying. They are cheap.

016-997-39-48 Governor Cover O-ring
005-997-86-48-M22 B1 O-ring
005-997-70-48-M213 B2 O-ring

I do not understand why you want to change the piston if it works OK. Mission creep sometimes don't work out. It is not difficult ( 6 on a scale of 1-10 ) to change the B2 cover o-ring. W124 chassis is a bit tight but still not too bad. You can always do the B2 when it fails.

quickster · #9 03-20-2017, 07:17 PM

I called the dealer today and he told me he could order a whole new piston, but he would have to ship it from Germany because nobody here has one in stock. I'm just going to do the teflon outer ring, bushing, and o ring. Will be going to see him tomorrow to visually verify that they are the correct parts.
Ah-kay, I remembered just a little while back when I took her out, I was taking off from a light. I put my foot down and the motor just revved for a couple seconds. Did not move. You know that cold feeling you get in your stomach when you think you're about to get stranded? I remembered that and figured it was a sign. I have a lift so it won't be bad.
In case anybody needs to know, MB price of B2 piston is $190. That's for 1990 722.418 trans

dieselbenz1 · #10 03-20-2017, 09:33 PM

That cold feeling you got was likely your b1.

quickster · #11 03-20-2017, 10:29 PM

The hesitation from stop to go is b1? From what I'm reading I thought it was b2. The cold feeling in my stomach was probably from the bm.

dieselbenz1 · #12 03-20-2017, 10:40 PM

722.4 has an upgrade for the sleeve if it's metal sometimes the piston binds and prevents engagement of all forward gears. The delay could be the dog bone driven by the piston the fix/ recommendation is to install the next longer dog bone they are available in 5 different lengths.

Diesel911 · #13 03-20-2017, 11:21 PM

If it still has the metal bushing you should change that. Also I think it would be of benefit to change the lip seal.