B1 Piston Leak
 

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?

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

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.

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

That's how it looks like:

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.

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