91 300SE no reverse & doesn't shift to 3d - Page 2 - PeachParts Mercedes-Benz Forum

gmercoleza · #16 06-13-2008, 03:29 PM

Also watch out for the little bits - don't lose them! It might be helpful to do on a kitchen table covered with plastic and really good lighting. You're less likely to lose track of things that way...

fred1948 · #17 06-13-2008, 05:06 PM

ON my '95 E320, there were 15 bolts that hold the valve body to the transmission and 3 of them are a different length and are also a different color. Just be aware and put them back where they came from. You would probably find it helpful to read the section (pg 57) about valve bodies in this repair manual for the 722.3 and 722.4 transmissions.

is another one that may be helpful.

I second the part about doing this inside in on a clean surface with good lighting and take lots of pictures of how things come apart. I used a large dining room table and arranged all of the parts like an exploded view as I disassembled. I then washed each part separately using two small containers of mineral spirits. Wash in the first and rinse in the second. As soon as the rinse starts to get contaminated, throw away the solvent in the wash container, use the contaminated rinse as a new wash and pour clean solvent for the rinse.

Some of the pistons and springs are a little tricky to remove and be very careful not to scratch any of the bores. This took me the better part of a day. When reassembling, dip the parts in clean ATF.

jerryb1 · #18 06-14-2008, 09:10 AM

Thanks so much. I'm anxious to try cleaning the valve body and I'll check the downshift button. I didn't even know it was there. I'll give it a try today.

jerryb1 · #19 06-14-2008, 09:12 AM

Thanks Guys;
This type information is extremely valuable to me. At least I have a few things to try before I spend a fortune or give the car away

jerryb1 · #20 06-14-2008, 01:49 PM

I have the pan and filter off. I see about 9 10mm bolts not 4. Not sure which ones or all of them need to be removed

jerryb1 · #21 06-15-2008, 02:45 AM

Quote:

Originally Posted by stevebfl

O-ring??????

Never seen that but we do atleast one a month with no reverse due to the clutches wearing out or otherwise failing. Every so often one of those so packs the governor passage screen with clutch debris that the unit also won't shift.

A repair of just the reverse clutch can sometimes be had. It will cost half or more of the real job. I haven't done one in years because it is plain stupidity to enter an antique mechanical device, spend half of what its worth to accomplish a small fraction of the repairs that would done if repaired properly.

The logic says the seals throughout the device are all 17 years old, the debris has likely progressed through the filter system into the VB screen to the governor requiring further disassembly.

There just aren't a lot of alternatives for a loss of reverse on that trans. Combine it with other symtoms and its rebuild time or replace time. The cheaper option to a quality rebuild is to spend half that amount (or maybe more) or a working 17-20 year old junk unit.

One other low probability option. The filter may be so plugged that replacement might allow driving the thing far enoughy to dump the problem on someone else.

Steve,
If I take all 16 or so 10mm bolts off aftrer removing the filter can I drop that part of the valve unit to clean the screens? Can you outline the proceedure. Also which models or years can I buy a junk to maybe replace the trans as you suggested if the cleaning doesn't work
Thanks very much
Jerry

jerryb1 · #22 07-03-2008, 06:22 PM

I took off the valve body, disassembled it, cleaned it and put it back together. I could not have done this without the various manuals that i found on line thanks to this forum. Well now it goes in reverse and actally shifts up, but i have other problems. When i start it in P then move the lever to N, I can't then go back to R or P unless I shut the engine off. Also, sometimes it stays in a forward gear when the lever is in N. I'm about to give up, unless someone can tell me it's somethiong simple that I now have to do.

fred1948 · #23 07-05-2008, 03:21 AM

Quote:

Originally Posted by jerryb1

I took off the valve body, disassembled it, cleaned it and put it back together. I could not have done this without the various manuals that i found on line thanks to this forum. Well now it goes in reverse and actally shifts up, but i have other problems. When i start it in P then move the lever to N, I can't then go back to R or P unless I shut the engine off. Also, sometimes it stays in a forward gear when the lever is in N. I'm about to give up, unless someone can tell me it's somethiong simple that I now have to do.

When reinstalling the valve body there is a slotted lever that has to be properly engaged with a pin in the detent plate. Also, make sure that the piston for the control pressure control valve is resting against the reversing lever. I have had my valve body off several times and almost reinstalled it once with the pin on one side of the lever rather than in the slot.