Greetings gentlemen!

I'm now down to 1 MB, my '92 300CE (124.051). I stored it late last winter and have been driving my truck instead. While it was sitting, the transmission (722.359) began to leak.

This weekend, I decided to take the time to put it up on jack stands and look for the leak. After adding 2 quarts of fluid, cleaning the area with brake clean, I was able to see exactly where it was leaking. Also, after the transmission warmed up, it stopped leaking for a day. Now, it's back to the slow leak. About a teaspoon a day if I were to guess.

What I found is that it's leaking from the B1 Piston/O-Ring. I have perused many threads here (including Army's awesome post) and feel pretty confident that I can accomplish this task without removing the transmission, though I may have to remove the exhaust system and lower the transmission some.

Has anyone ever had "just" this o-ring leak? The transmission is tight and clean everywhere else. If I do have to remove it, I might consider looking into the really sloooow reverse engagement problem, unless that too can be corrected from the outside.

That all said to say - I'm looking for the O-Ring and a part number. And, to ask - where the best place is to purchase an o-ring? Oh, and I hope I don't have to buy a whole gasket/seal/o-ring kit.

Thanks! I welcome your thought/suggestions.

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1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

I did the B1 o-ring without lowering the tranny or removing the exhaust. Link and info here. The part number is for a 300SDL 722.321 but it may be the same. I would rate it 7 on a scale of 1-10 in difficulties. You have to be very patient. You need to make some kind of a tool as the spring is very strong and no way you can push it back in by hand. I think MBZ has a tool for it with the tranny on the bench. So it is very hard when you are on your back side, if you do not have a lift.

Good luck.

300sdl tranny leak here with picture

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Awesome! I'll see if I can get the part by this weekend and make it a Saturday project. Thank you!

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.