For the past two days my car has been having problems going into reverse. At first it would would jump and jerk before finally engaging. Now there is no reverse at all. Fluid level is ok. Is it time for a new tranny?

No reverse
 

I had a similar problem with a 350SE I owned. I took to my trusty MB mechanic (notice I said MB mechanic and not Trasmission shop). Turns out the transmission could be adjusted (reverse at least) apparently on that transmission there was some sort of pressure nut that could be tightened. Alleviated the problem whereby the car seemed to be straining to move backwards.

Sounds like yours might be a bit more serious. Stuck vavle, binding valve, dead pump etc.

You might want to have it diagnosed by your local MB dealer and then decide what to do from there.

Used MB trannies really aren't that expensive (depending upon model).


Good Luck


Chris M
71 250CE

Which tranny? The 722.0/1/2 trannies have a band piston that brakes or blows its seal. It can be fixed from the outside.

The 722.3/4/5/6 trannies don't use a band for rev they use a clutch brake. (multiple clutches, splines to the trans housing). These trannies will need disassembly usually; for lack of reverse.

Missing Model Info
 

My car is a 1988 420SEL. Has 159K on it. Thought the model info was in my profile. Sorry about the omission.

Sorry, but you have a 722.3 tranny. You probably need a rebuild.

lost reverse?
 

Sometimes what happens is either the seal around the input shaft to the clutch pack or the 'o-ring' seal around the clutch apply piston cracks and leaks, resulting in no or slow/weak reverse engagement. Tranny works fine in forward?

A GOOD MB tranny shop will fix just the reverse clutch pack (the first one when disassembling the tranny. Should cost $130-150 parts and labor for the tranny fix if it's only the reverse clutch pack. No need to do the rest unless you want/expect another 140K miles.


Removal and reinstallation are a bear and cost?.

I have repaired just the reverse, IF everything else is just right. You have to pay for the parts plus about 10-12 hours labor I think. (Don't quote me on the labor, I haven't looked up the time involved...Just a guess)

If they have to yank the tranny,I would have them rebuild the whole trans. I have never worked on a Mercedes Trans but on the General Motors, Ford and Chrysler transmissions that I have rebuilt, the other clutch packs will show some wear even though the seal will fail on one clutch pack, espesially with 150k on the clock. If reverse has been slipping there will be a lot of cutch material in the fluid. Benz's are very sensitive to "stuff" in the fluid and may cause irregular shifting problems down the road.

Thanks for all the helpful response
 

Thanks to one and all who have responded to my post. After reading them and talking with a few in the know about MBs in North GA, it seems that I'm looking at replacing the tranny, either a used one for about $750 (salvage price) and $250 labor to pop it in, or a rebuilt one for any where from about $1400 to $2600 depending on where I get it. The car will still go into reverse with some coaxing ( you have to rev the engine before it will engage), so I have a little time to decide. One guy recommend I try X Trans treatment to see if it helps. Might do that first. Anyway, I like the car and plan to keep it for another 2 years or so. Again, Thanks.