Did I eff this up? - PeachParts Mercedes-Benz Forum

lsmalley · #1 10-09-2013, 06:05 PM

I recently took out my transmission valve body (722.4) because of the slipping and no reverse. I was looking for any of the things listed in the photo (stuck accumulator, leaking/cut seal, etc.). The only thing that I noticed was that the plastic part that I circled in red had these 2 rubber rings on the end that both had diagonal cuts and the rings seemed to have shrunken in size as the plastic piston thing was able to move up and down in the chamber freely and even had wiggle room for side to side movement. I assumed that the rings should not allow movement from side to side and also those rings were maybe supposed to stop fluid from flowing past (I don't know). So what I did was replace those 2 rings with new o-rings. Car was fine for a few days, now I am noticing flaring and erratic shifting behavior. Please help.

thayer · #2 10-09-2013, 06:22 PM

Good lord why haven't I seen this document before, I'm going to my car. I'll be back after a while.

duxthe1 · #3 10-09-2013, 08:21 PM

I /think/ that those "o-rings" are actually teflon seals and are supposed to have the diagonal cuts. It may be that the o-rings held for a little bit and then blew out.

FWIW, in my valvebody excursions I learned that a pan gasket is only good for about 10 removal and replacements. Keep a new one handy but only use it when your current one tears going back together.

thayer · #4 10-09-2013, 10:32 PM

those rings normally have that slit in them. the same rings are on the oil pump. the slit is so that you can install them as they don't have any stretch, they aren't rubber.
You put rubber o-rings on the piston? Thats fascinating, did you regain reverse?

thayer · #5 10-10-2013, 09:00 AM

Thayer

thayer · #6 10-10-2013, 10:20 AM

I'm ordering a new switching on piston and spring kit for the accumulator. I'll share part numbers and pics once I get the new one and compare the new to the old to see if size is an issue on the rings. I doubt that the Teflon rings ever shrink, but I have been wrong before.

thayer · #7 10-10-2013, 11:27 AM

Allright, those individual parts are UNOBTAINIUM per merc of Winston. I've also queried Roy, hopefully he will have a trick up his sleeve.

Looks like the next best bet will be to parts yard 722 trannys and dig in in the gravel.

lsmalley · #8 10-10-2013, 01:50 PM

I wonder why you can't get those parts? Did you try sourcing a local transmission shop? I need to open mine back up and get those o-rings out. I think they are causing the piston to stick. I also think I may have put the larger piston with the o-rings in wrong. Are the springs all supposed to be pressing against the metal plate? In your picture it looks like the springs are the first thing you see when you take the plate off. Even in the diagram I have with the accumulator circled in red, but when I removed mine, the accumulator was the first thing I saw. It even has the print of the accumulator against the plate. Is it possible for you to line up the pieces from your valve body and share a photo please? I suspect that mine maybe was tampered with before and I have never known. THANKS.

MAVA · #9 10-10-2013, 01:59 PM

Gentlemen,

This is my opinion, I come from the point of view of I've rebuilt my own transmissions...

When the valve body bolts are loosened up on a 722.3xx through 722.5xx one disturbs the gasket and the 4mm flat plate that mates the valve body to the main transmission, but the kicker is the krud on a few of the valve passages seeps out, and no longer will you get a seal on the mating surface on the valve body, and a transmission is all about pressure....The 722.6 does not have this issue

So The easy fix is to get a new gasket. I cleaned the mating surfaces (swab clean those black passages)with denatured alcohol. As far as the new valve body seals. I could not find anything except for K1 and K2(K1 and K2 are the same) from Mercedes, but Precision International makes a whole kit for the valve body for the 722.3-722.5 which is excellent

Get informed ...

See the last post:

Transmision work shop manual - Benzworld.org - Mercedes-Benz Discussion Forum

K1:

DIY Mercedes 722.3 722.4 722.5 Transmission K1 Piston Spring Repair Kit Install - Benzworld.org - Mercedes-Benz Discussion Forum

Transmission

Best of luck,

MArtin

thayer · #10 10-10-2013, 03:03 PM

Thank you much Martin, this forum is all about getting informed.

MAVA · #11 10-10-2013, 03:34 PM

Thayer,

You are welcome if you guys need some literature PM me your email as the files are to large to post here.

Also, call Dacco transmissions, they sell to end users. I know they have the whole transmission kit, but I think they will sell you the valvebody kit-large gasket-rubber o-rings, and teflon o-rings. I've used their kits, and they are excellent..

DACCO Transmission Parts | America's Largest Remanufacturer of Torque Converters

It is best to replace all the o-rings if you remove the valve body..

Best of luck,

MArtin

lsmalley · #12 10-13-2013, 08:17 PM

I ended up buying a new valve body.....(well used one from a 300E). I'm not quite sure what I did wrong with mine, but the shifting was flaring. New one seems to be working fine.

thayer · #13 10-19-2013, 07:15 PM

Did you ever get reverse back?

LandYaghtLover · #14 10-19-2013, 10:39 PM

Im curious too. I always wondered if there was another source for the reverse issue and would like to give this a shot before replacing the reverse band. Mine certainly chatters then it bites reverse good.

LandYaghtLover · #15 10-19-2013, 10:48 PM

Quote:

Originally Posted by lsmalley

...the accumulator was the first thing I saw. It even has the print of the accumulator against the plate. Is it possible for you to line up the pieces from your valve body and share a photo please? I suspect that mine maybe was tampered with before and I have never known. THANKS.

That may be normal:

"The "D" and "E" shift control pressure valves can be found to be installed valve first then spring (early) or spring than valve (late)."