jimbo1763

Very randomly, my 2007 E350 will hard downshift without warning. My guess is that it drops at least two gears. It has usually happened at 10-20 mph, but this afternoon it was at 35 mph. RPM's shoot up momentarily, then it settles in again. It has done it to me both in Comfort and in Sport mode.

I have reset the learning feature of the transmission, and I have had the fluid changed. No joy.

Taking it in for diagnosis tomorrow. Hope it left some codes.

Any ideas, or any suggestions? It is a little unnerving, not knowing when you are going to have that happen to you.

Benz-O-Rama

TCU software update, and probably the valve body. Common....

jimbo1763

Valve body sounds expensive...

I am at about 87K miles.

Benz-O-Rama

Hmmmm, depends on what you consider expensive I suppose.

Every single 7G MB I've owned has had to have the valve body replaced and the TCU software updated, for shift quality issues. The good news is, the problem is usually fixed for good.

Original trans fluid at 87K? You might get lucky if it only needs a flush and filter. Fingers crossed....


Edit...just read you had the fluid changed already. So yeah.... valve body....or the trans connector is leaking, and fluid has wicked it's way up to the TCU.

jimbo1763

I have already had to have the balance shaft repair. I hope it is something reasonably simple. The abruptness of the downshift and its randomness is unsettling. Certainty as to what is going to happen in driving is pretty fundamental.

I like my car. It is comfortable and frankly fun to drive. But I am not keen on its reliability. This was my first Benz.

Will let you know what the dealer has to say. Thanks for the response.

jimbo1763

Dealer says it threw a code and that it needs a "conductor plate," which I understood him to say is the same as a valve body. Part is in short supply, had to be ordered, will take a week or so to get here.

I am pleased that it threw a code. Otherwise, on these random issues, how do you ever know what it is, unless you just start replacing things?

Benz-O-Rama

Yup, I've never NOT changed a valve body on any 7G I've owned.

jimbo1763

Valve body change completed. I am still trying it out, but so far, everything is very smooth.

Benz-O-Rama

Yep, common problem in these 7Gs.

apl175

There was some procedure that I saw in a MB produced video where the valve body is removed, and each valve operating unit is removed and cleaned in transmission fluid. The screen on each valve is also cleaned with a heavy magnet, along with the socket that each valve fits in.

There is also a torque converter, and valve adaptation procedure that can only be activated using the Star tool. The valve adaptation is done against both temperature as well as torque. The Star tool will tell you to accelerate and hold a certain number of Newton-Meters of torque for several seconds etc. The "Time value for filling each engaging element" and "Correction of hte pressure value for applying the engaging element" are adapted in this way.

Always wondered if someone attempted to try this. I'll try to find the video on youtube.....

Pekkle

I have the same issues, before my warranty was up, the stealer told me MB doesn't want to replace the valve body unless it's a must, so they reprogrammed my transmission instead and that never fixed problem. Now I am out of the warranty and with 76k miles how much is the valve body? I heard it was around $2000? anyone knows exactly how much it's going to cost to get it replaced? btw, I have not flushed my tranny fluids yet. maybe I should just replace the valve body instead? I heard the tech told me when they replace valve body they also flush the tranny fluid.

jimbo1763

It does result in at least a partial fluid change.

Since you raised the issue while the car was under warranty, suggest you ask MB to make a goodwill contribution toward repair cost. You may be surprised. I was at 87K miles. They did the reprogramming on mine as well while under warranty-no joy, as the issues continued.

apl175

Link to video:
http://youtu.be/v3Ohs9qb4pc

gaazmon

my uncle had to change the valve body on his 2007 S550 when it was under 20K miles. they all need it (sounds like faulty design if you ask me *cough* *cough* lawsuit *cough* *cough*

no wonder the 2010+ cars come with the cars preprogrammed to C mode and when you turn the car off it defaults to C

Pekkle

Jimbo, at 87K miles did the dealer help pay any cost? if so how much did you end up paying to get the valve body replaced?

jimbo1763

The dealer quoted me $1100. I asked for MB to consider a good will contribution, and it did so for a few hundred of that. Your experience may be different, of course. I have always gone to the dealer for service (as did the prior original owner), raised the issue during warranty, went through the other interim fixes, had them change the fluid at my asking, etc.-stayed pretty proactive about it.

Pekkle

Thanks Jimbo,
Let me go talk to my service adviser and see if he can help me out and give me a break.

ttawd

Darn it. My 2008 E320 Bluetec has been doing the hard 2 --> 1 downshift since the beginning. I cannot dulicate it on command, and the dealer never found a code associated with this problem. They could not duplicate in either. It is very intermittent. It is just plain inexcusable to have such an issue on a $60K car. They checked the pressures for all the gears and were within spec. The dealer also flushed my transmission fluid and changed the transmission filter at 40K miles. Now I an out of warranty and have 78K mikes. I should have insisted before 50K to do something to the car. I'll be due for another transmission flush at 80K.

Argh, I hate lying dealers, and faulty designers. They should just recall all these 7 speed transmissions.

-Mike-

konigstiger

If they have not already done so reference S-B-27.00/107a - applicable to 211.022 (e320 Bluetec), 164.122/822 and 251.122) the engine control & transmission control modules “may” need flashing inclusive of SCN coding. Check PM.

09W211

I have a 2009 E350 non Bluetec and I'm having the same issues. I get that hard random knock from 3-2 2-1 at times, very intermittent. My sales guy drove my car and was able to replicate it a couple of times so we took it into the service department and put in a complaint. I got the car back, and again the service department said they weren't able to replicate the transmission knock and the computer wasn't picking up any fault codes.

Can anyone point me in the right direction please?

Thanks,

jcat

The 7 speed at low speeds is shall I say...imperfect. It feels like its constantly trying to find the right gear instead of staying put. My e500 4m has the 5spd, and occasionally I'll get that hard 2-1 shift, but then damn near every Benz ive ever driven (4,5,7,8 sod autos) has done it. My car also tends to hang in gear for longer than I'd expect, but again every Benz I've driven does that too.

lalulu

hi - i have a 2014 E350 that does the same thing - randomly downshifts to MANUAL 1 causing the RPMs to roar.
Dealership keeps telling me they can't find a code.
I keep bringing it back.
They just said they found a faulty steering column module and replaced it.
I know NOTHING about cars - could a new steering column module possibly fix this problem? From what I see in the chain here you all are saying the VALVE BODY needs replacement.

Thanks for any comments!