Your good... I just got a call... The transmission control unit did not fix the problem... They called Mercedes and are in the process of replacing the torque converter... They said it is the next step in the process...

 

cool thanks for the update!!

 

My service advisor called and said replacing the torque converter did not fix the problem... but... I now have a new transmission... My question... an '04 with 38,000 shouldn't need a new transmission... I'd like to know it's not going to happen again... I'm picking the car up tomorrow mid-morning... I'll do my best to find more...

 

the original cause of the problem is the valeo rad they said it doenst have, but the rad was defective causing antifreeze to get into the transmission cooler lines and then goes into the torque converter and then to the transmission. there are also issues similar to your complaint that are control units and torqueconverters that are not related to antifreeze in the trans fluid. if you have a problem again with the same complaint within a year the car should still be covered under the Mercedes Benz parts warranty which is 1 year unlimited miles. Good luck.

 

If I learn anything else, when I pick it up, I'll post a final update... Otherwise, thank you for the info... It has been very helpful...

 

RE: 2004 C320

Note: In September 2007, the earlier posts were resolved with MB replacing my transmission at 38,493 miles... It was still under warranty... Today, not in warranty, at 43,941 it begins again...

A couple of weeks ago, I drove a few miles and stopped for a very short time… I got back in the car and as I was getting back on the road, I heard a low moaning/groaning sound. I thought it might just a bad spot on the road. All seemed OK heading home.

Yesterday that all changed… Again after a quick trip, as I was getting back on the road the same groaning/grinding sound… This time it started bucking at low speed. I remember it well...

Not to repeat myself… Please read the earlier posts as it is a revival of what happened during September 2007.

I've an appointment with MB on Tuesday, Sept 8th... Any info/ideas I can have will be very beneficial...

 

They kept the car for two days… After a number of attempts to recreate the problem, they said they could not. I went to pick the car up this morning…

Not being that knowledgeable about cars maybe I just was not phrasing it well.

Before I left the dealer, I went on a test drive of my own in the back parking lot. I got the car up to 20mph and took my foot off the accelerator. It bucked… I took a corner heading back to the service department… It bucked and droned… I slowed down so not to hit an SL550, my insurance company would have been very disturbed, and it bucked… I parked it immediately…

I went back in and talked with my service advisor. He asked the shop foreman to take it for a spin. I was asked if this was going on at low speeds… We didn’t get 100 feet before it started bucking. He asked all the right questions. As he made his first turn, it droned. I was overjoyed. He knew exactly the problem.

It’s the radiator issue. I didn’t think the 2004’s were part of the service bulletin. Anyway, he ordered a glycol test.

If the glycol tests positive, they replace the radiator and flush the transmission and coolant systems. If it tests negative, I get a new traction control unit. New programming is supposed to fix the problem. FYI: the droning is coming from the torque converter. It’s not locking up but it’s being effected by the radiator issues…

I’m driving the loaner once again… I’ll post any new info I get… I should get my car back Monday or Tuesday…

 

I was having a similiar tranny problem with my '04 C320 with only 35k. The dealership said I needed a new tranny and torque converter @ a cost of around $6k. After reading this thread I suggested that maybe it's the Control Unit or Elec. Conductor Plate, or even a Rad leak. They said I was probably throwing away money, but they'd give a try. Low and behold, $1,300 later the problem is resolved. It turned out to be a faulty Control Unit.
Thanks to this forum I saved myself $6k!

 

I'm very glad the post was helpful...