B1 Piston Leak

[deanyel]

re: 1992 400E, 722.354 transmission

I believe I have a B1 piston leak. There's lots of info on the B2 seal but not on the B1. Can the B1 piston seal be replaced without removing the transmission?

[myarmar]

I've done it on W140. Not sure you got enough room on W124. Also, threre is a VERY strong spring there. After the fact I was wondering if there is enough room to push the cover inside to expose the O-ring without the lock ring and piston removal. Not sure it is possible.
Mike

[deanyel]

Perhaps I can invent the on-the-car-B1-spring-compressor. But that seems to be the critical question - can I get to the seal by just pushing the cover in, or do I have to take the cover/piston/spring out first. The latter sounds a lot tougher under pressure in tight quarters.

[S-Class Guru]

I did one on a 722.3 today. I don't think you can push the cover in that far, it's at least 1/4 inch to the o-ring. And if you could, you would have to be using some device to hold the cover in under strong spring pressure while you miticulously removed and replaced the o-ring. If you had such a device, you could just as easily remove the cover and piston to reach the 0-ring.
That b-1 spring is strong, probably 50 lb to depress past the clip.
I would envision some type of lever, like the old Chevy cheap valve spring compressors. If you can rig a lever, say with 4-1 leverage you could compress the cover, pop the circlip, slide the cover and piston and springs out, and pop a new o-ring in. But where to anchor the lever is the question.
With the tranny out, i could fulcrum it on the oil line bolt, like the factory tool mounts, but with the tranny in the car, you would need to fulcrum it above the b1 cover I think. Think baling wire, big c-clamp or something along that line.

DG

[myarmar]

That's how it looks like:

[deanyel]

Now it's not leaking anymore, not a drop since the original post. Darn car - just when I get interested in fixing something it fixes itself. That's quite a spring in the picture. I crawled under it again today and there's certainly more room than the B2 but it's very tight, and the B2 doesn't have the big, powerful spring. I think I could compress the B1 cover with a 12 inch bar clamp hooked to the other side of the transmission, and then remove the circlip, but there's no room to pull out a big spring and piston like that, especially under a lot of tension. It looks like fun - but I'm not going to try anything until it starts leaking again. Thanks for the help.

[S-Class Guru]

Good idea, it's difficult to fix even with the tranny on the bench.
The spring, however, loses tension quickly as you extract it.
About 1 inch out, it can be handled by hand, it's getting it in that last inch, and holding it straight while you set the circlip that is difficult.

DG