91 300SE no reverse & doesn't shift to 3d
 

All of a sudden when i put the car in reverse nothing happens plus when I drive it doesnt go above about 40 mph, like stuck in 2nd gear. The car has about 150K miles. I had to repkace the torque converter about two years ago. The fluid looks clean and was at the right level. Can someone tell me what the probable cause would be and what I'm looking at?
Thanks

More than likely a blown "o" ring inside the transmission.

Can it be repaired? or am I looking at a $2500. rebuild or replacement transmission?

Can you provide a few more details?
Did both problems occur at the same time?
Was reverse making any noises or did it take a long time to engage prior to not working at all?

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.:(

My son drives the car. There was no problem prior, other then sometimes it seemd to delay shifting from 1st to 2nd when cold. He called me from work and said he couldn't back out of his parking space as it acted like nuetral in when he put it in reverse. I told him to push it back and drive it home. He did that, but said it would not shift to high gear and rpms were higher of course, so he drove home slowly the back way. I just started the car and reverse now works! Could it be a clogged filter? I havn't touched it since the torque converter repair, and I assume the trans shop replaced the filter at that time, but I don't know for sure.

Steve offers good, knowledgeable advice, as always.
When my reverse plates died, the pan and filter were full of little pieces of friction plate. Easy diagnosis if you drop the pan and cut the filter open.
As Steve said, generally not worth it to pay a mechanic to just do the R plates; sure as taxes, that crud will mess up something else (ask me how I know).

DG

Thanks guys,
I'll take off the pan, change the filter and see what happens.

I took off the pan and replaced the filter. There were no metal shavings in the fluid and it looked pretty clean. Reverse now works, but it still doesn't shift to high gear when driving. Can someone tell me what the probable cause is? My guess this is a common fault with these transmissions.

Before I did anything, I tried reverse the next day and it worked. I changed the filter and fluid, reverse works fine, but the car doesn't shift from low gears
Also, I found a 1989 420 SEL for $900. Will I be able to use the transmission from that in my 91 300SE?

I had a similar issue on our W124 after the tranny was replaced. It was a bad (or possibly clogged) valve body (the shop didn't say). If changing the filter brought reverse back, then's there's a good possibility that you have debris in the valve body. The valve body isn't hard to remove, but it does have a bunch of small parts that could fall out/get lost. Proceed at your own risk.

Todd

Thanks Todd,
Do you know what's involved to take out and replace the valve body. Can it be removed without taking out the transmission?
Thanks
Jerry

I had a very similar problem on my W124. Reverse worked fine, but one day it just got stuck in 1st gear and wouldn't shift out of it. I pulled the valve body and soaked/flushed it. The PO never changed the fluid, and all this gummy stuff came out. Reinstalled, filled with Mobile 1, and it shifted like new. That was 3 years ago. I sold the car to a friend and he is still driving it with no tranny problems.

One more thing, check your downshift button under the gas pedal and make sure it's not stuck. That will also prevent the tranny from upshifting.

The valve body can be removed without dropping the trans. Take off the pan and you'll see the valve body (the filter is attached to the bottom of the valve body). I think there are 4 10mm bolts that hold the valve body on. I don't remember it being mechanically difficult, just nerve racking (I hate tranny issues). If you do remove it, be carefull reinstalling it. If I recall correctly (it's been 2+ years), one bolt is a different lenght. They are also easy to overtighten and strip.

Todd

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...

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.

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.

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

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

cleaning valve ubit
 

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

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.