Lost reverse instantly. All foward gears and shifting work fine. 150,000 miles. Dropped tranny, filter clean, acclumination of very fine metal in pan in very small amount. Removed valve body no discoloration or foreign pieces. What part failed. Neighbors car. Didn't read codes first before disassembly. Can I flush torque converter and lines and cooler and replace a part or make an adjustment due to the small amount of metal that appears to be normal wear and tear?

The reverse clutches failed. This is the most common problem that trans ever has. In the later cars (yours is a later car) the pressure plate retaining spring plate deforms and lets go releasing 20 or so clutch springs making a mess of it. Not really any worse though just requires the springs and a plate and occasionally a drum.

While this clutch is the first one to be removed on disassembly, the occurance of debris requires a complete disassembly and cleaning. All clutches, an occasional band, all seals, a thrust bearing or two and its like new. The short story is that it needs rebuilding.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Try a search - lots of info. Lost reverse instantly probably a blown reverse piston seal, transmission needs to come out.

Wouldn't I have some (alot) of clutch debris in the pan if the reverse clutch went bad? I think the reverse piston seal failure is more probable if the visable debris evedience in the pan ( or lack of it ) can be used as an indicator. Does the reverse piston have another name so I can locate it in the MB manual ( exp. b2 clutch ).

When the spring plate comes apart, there is very little evidense of it in the pan. The springs all wad up like a high intensity brillo pad and do a little machining of the drum but most of it is contained in the clutch pack itself.

Doesn't really matter what and speculation is fun but rather useless. Your parts order only can be made after disassembly and inspection.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Lip sealing rings of the B3 piston, but I was going to say the same thing - doesn't really matter, transmission has to come out, and you're going to fix both of them anyway.

I want to thank you both for the info. I will put in a rebuild kit. Just one last question can I save the torque converter with proper cleaning?

Sure, you can just fix reverse if you want to, first thing you come to, many don't do a full rebuild. You should subscribe to EPC if you haven't already, now free.

https://epc.startekinfo.com/epc/welcome.jsp

I just had my wife's 1989 290e 2.6 transmission apart, for the same problem: reverse failed.

I found exactly what Mr. Brotherton described, only not as far gone. There was no evidence at all in the pan. The fluid looked prety good, but not really clear.

The reverse clutches no longer had the little springs to hold them apart, so they were worn out, although the steels were fine. The big ring on the clutches was cracked. The rest of the transmission was like new (except the seals, which were like hard plastic). You could still read the printing on the inner surface of the bands.

My rebuild kit had clutch plates, but only 4 of each type, so I had to buy two more from Mercedes. (I figured I would replace them all, since I had most of the clutches anyway.) Total cost: $135 for the kit, $95 for the parts from Mercedes.

As Mr. B. said, you don't know until you open it up.

Andrew
1989 190e 2.6
1990 Jaguar xj6

One thing I learned long ago that especially appies here, is to never skimp on materials. This especially appies when the materials are a small portion of the cost of a large job and especially when the materials are rubber products.

We only use Mercedes parts when we build a transmission. That especially means the seal kit. There was a time when that wasn't the case and we had had a few comebacks specifically identified to reduced diameter seals particularly the servo lip seal and the nylon o-rings for 4th gear.

As pointed out the parts are inexpensive. We charge 17 hours labor for the whole job so whether the labor is free or it is 75% of the job, it sure pays to never go there again by using the best materials.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician