W 140 Trans. Problem

[Rocket]

I am seeking informed opinions on a transmission problem that occurs on W 140 body mercedes. The car in question is a 1992 500 SEL with about 130K on it. When you put this car in reverse it will only roll about 3 or 4 inches and then the drivetrain locks-up. This problem began at once and has never gone away. I'm assuming a broken servo or one-way clutch has failed but would like other opinions. I saw the same failure on a similar 140 a couple of years ago but the owner took it to the local dealer who simply replaced the trans., so I never found out what went away. Your help is appreciated as always.
Thanks to all

[Benzmac]

I wonder if it could be something as simple as a clogged up cooler or pinched line? I am not sure where, but I have heard of this somewhere before.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

[Fred Berry]

I have my 92 500 SEL in the shop at Precision Motorcars where Aaron Greenberg works for this same problem. I also had problems with the oil pressure. I will call them on Sat. to find out what they think is the problem. Mine was slow to engage the reverse gears but I did not have a lock up. I posted this question before and some thought it was a reverse servo valve problem. I will let you know what they have to say about the fix.

Fred

[efoley]

The b3 reverse clutch pack will have excessive clearance - the frictioin plate material falls off - the servo poiston overtravels - the friction material also can block the filters screens for the governor

[oldsouth]

Same thing happened to mine about 3 week ago. Had to overhaul the transmission. Look for a reputable company that had experience on Mercedes units. Only thing a dealer will do is a Mercedes exchange for about $4500. Had mine rebuilt for $1500.

One question - is there an adjustment for pressure on the exterior of the transmission. Sometimes mine now shifts with a little hesitation expecially 2-3 and 3-4. Will only do it at part throttle, never at full throttle.