K-A

Sometimes when I'm cruising super slow, like as in barely hitting the gas, or slowly de-accelerating to a stop without applying the Brakes, the car doesn't seem to know whether to stay in second or go into first.... And every once in a while it will downshift into our oh-so-closely geared 1st which naturally causes for a VERY hard and jarring downshift experience. It worries me that when it happens it does some possible wear related damage to the Tranny?

Anyone ever experience this?

oc79

Check ou this thread.
I had the same problem and it was my Transmision mount.
https://mbworld.org/forums/e-class-w...d-feeling.html

ap10046

Hi K-A, Everyday...!!! I go through the same, especially in traffic.

Barry45RPM

Its a well documented complaint about the 7 Speed Tranny. There are various fixes that the dealers have access to. Just tell them that you feel a "Bump from Behind, 2nd < 1st downshift"

K-A

Yeah I figured there were many victims to it. Fortunately the bumping has almost completely gone (was insane when I first got the car), I took it in a few times and they kept telling me that it would fix itself, now this hard downshift barely happens, but I'm going to mention it when I take it in for Servicing next week.

timannnn

Mine does it when coming up to a red light and I don't stop the car (slow roll stop). If I stop right away the tranny is fine. Took the car in and they said all it needed was a software update. Car still does it even after the "update".

Elover

the update doesn't work...... it only helps the shifts in the upper range... it is actually an engine flash.. not a tranny flash.

the tranny valve that people are talking about is the culprit.. it is a $3000 fix and the dealers are not apt to want to replace it all that easily.... they will give you the runaround about the flash... and possibly the fluid flush.. the valve has to be changed.

K-A

I'm going to push hard for the Tranny Valve then. Is there a more technical or exact term for this part?

Polar Bear

Yes - valve had to be replaced on a W209 CLK 722.9 under warranty.

Barry45RPM

I'm no mechanic & don't wish to inject confusion here... but is it the same as the "Valve Body"? (The Valve Body IS the defacto director of HOW the transmission shifts. The computer is the director of WHEN it shifts.)

Trey

Yes, it's the valve body that is replaced. Mine was done about 3 weeks ago and the car still has the same symptoms. It is back at the dealer now being looked at again. Not sure what the next step is; replace the transmission?

Barry45RPM

I have an '07 which I got new to replace my '04. It happens occaisionally in my '07 too. They have never solved the problem, but it happens far less often. Especially when cold. When I want the transmission to perferm flawlessly, I switch it into C mode & drive it like that.

SPNJHockey

I too have an '07 (4-Matic)...used to only use "S" setting. About 2 months ago I first noticed the hard dnshift when coming to a red light. Very annoying if you like to stop without feeling the actual moment of stopping. I tried switching to "C" mode, and it eliminated the annoying feeling.

After 9 unsuccessful tries at eliminating the tapping noise from the moon roof cover (inside), I'm not about to even try this complaint!

konigstiger

If you want a copy of WIS for sunroof panel DIY, PM your email address.

SPNJHockey

Once again, thank you for being one of the top 3 board members - for being so helpful (and even when unsolicited).

starcarnut

Just got my 350 and it's doing the abrupt 2-1 shift. Car is going in in about 2 weeks for a once-over, thanks for bring this up, I thought I was just being picky. Kinda has me worried about mechanical stress.

K-A

Exactly. The mechanical stress is what's freaking me out the most, I mean these hard downshifts can't be good for the Tranny at all. I'm covered for over another 3 years, but if I were to keep the car after that, I'm worried all that stress may climax into a Tranny meltdown.

starcarnut

I'm hoping that a software update fixes it, it only does it once or twice a week, not daily. My warranty is up in 3k miles.

TheRealG

can someone explain why the new valve body in the tranny helps - what's different from factory?

G.

Barry45RPM

The very simplest, most graphic image I can paint for you is as follows:

The valve body looks like a big flat maze thru which transmission fluid flows, controlling how (not when) the tranny shifts up & down. If they change any of the holes or maze passages within the valve body, the shifting smoothness has been altered because the pressure of the transmission fluid which (roughly speaking) moves the gears has been altered.

Don't think of the valve body as a single valve like on a garden hose, its a maze of passageways that looks like a map of downtown streets a couple of layers deep... sort of.

Trey

Here's what they look like internally.



I got my car back yesterday after the dealer looked at it again. It is still bumping down to first coming to a stop. I also had a rough 4-5 shift that was worked out. I will take it back for try # 3 at some point, but will wait until I need something else done at the same time.

Lance310

I have a 2007 ML320 CDI and had the same harsh downshift problem. The dealer installed the software update and fixed it. No problems since the update approximately 2000 miles ago.

jerome8283

I'm a fairly new owner of an '07 350 Sport and noticed this problem. What is the final fix for this? Thx

Tjdehya

I would like to know too because I have the same problem with my 09 E550. I thought that it was just the car downshifting too early which I hate, if it can be fixed I would love to know.

Barry45RPM

IMHO, If it aint been perfected from '04 till today, thats the way they're gonna stay... and they have been trying to perfect it since late 2004.