6hift

My tranny is currently not smooth. It hesitates or jerks when coming into certain mph. It does it around 25 mph, 40mph and 55mph. Taking the car in tmw and hope they fix it. It's bothering the crap out of me.

MB Fanatic

What car do you have and what year?

6hift

2003 E500

GearHead

You may need a new radiator, rebuilt tranny ....

Mine had the same problem recently, radiator leaked and contaminated the tranny.

GL

JDM_SXE-10

How much did this run you and where did you take it? I'm starting to experience the same symptoms.

E320joy

Mine did this too. I took it to the dealer and it needed a new transmission control module. That seemed to fix it, though it still acts a little strange sometimes (holds gears a little to long). That could be caused by the programming which i'm going to have checked on the next service visit.

GearHead

Fortunately for me, my car was still under warranty.

The exact service bulletin related to this repair is P-B-27.55/50f

This bulletin covers the

Test for contamination within the radiator
Replace radiator if necessary
tranny flush
Replace tranny if necessary.

My car was in the shop for 8 days while this was performed. Oops, almost forgot, took my car to SouthBay Mercedes

Hope this helps

harkgar

I think I have read about this problem somewhere else. What is the mechanism of contamination? How does the radiator coolant get into the tranny?

GearHead

Good question.

I had wondered why a faulty/leaky radiator can cause contamination within the tranny.

Within the service bulletin listed, there is a description on looking for a certain amount of contamination within the tranny fluid and that will corelate the condition of the tranny, and the need for replacement.

So, I am still baffled on how tranny fluid can be so easily contaminted.

georgedaman

fluid density,.heat,pressure,negative pressure..etc..youknowwhatimsayin'

Barry45RPM

There is a line (pipe) that carries Transmission Fluid to and thru the radiator, so that the heat in the trans fluid can be dissipated out the fins of the radiator. This line passes thru the coolant chamber of the radiator but remains separate and closed off so that the fluids can't comingle. When a seam/joint in this tranny pipe develops a hole in a part that is inside the radiator, antifreeze and trans fluid and water mix together and are carried thruout both of these 2 formerly separate systems.

Water and antifreeze are mixed with the Trans Fluid and sent back to the transmission. This spells death to a transmission.

6hift

Thanks for all the help guys. I just got my car back from the dealer and they fixed it. What they did was replace the valve body in the transmission, changed the filter, oil and everything was back to normal.

I've heard about the bad radiator but he said my radiator was still good. I'm just hoping that things don't go bad later on with the radiator and such.

E500 Benzo

what was the cost for all that? im assuming you were out of warranty (2003)?

vettdvr

And since cooling system pressure is greater than the pressure in the transmission recyle line the antifreeze enters the transmission fluid.

benzliku1it

was this happening in the mornings when the car was cold or at all times? im having the same problem only ehrn car is cold.

sunkist

E320joy,

I just had my car taken care of as well at my local dealership about 2 weeks ago. They replaced the TCM, flushed the tranny, replaced some seals, motor and trans mounts, coil pack, spark plug wire, and spark plug for cylinder #4.

My car was also holding the revs for a while until the trans fully adapted to my driving. Maybe your SA forgot to tell you that they reprogrammed the TCM to fully adapt to your driving habits over the next 750-1000 miles.

Now its back to being silky smooth like the day I picked her up. Extended warranties are a must for these earlier mercs.