moonrkr23

hey guys,my g/f went out today and on her way back home on the interstate was lagging and would't shift to a higher gear. the rpm's were high. when she got out of the car to put in the garage she smelled something burning. when she got back into the car and put into drive it shifted hard so she tried again and did the same thing. then when we drove it later it ran fine but still lagging some. any ideas of what that may be? i haven't seen any leaks. thanks

W203E35

Have you ever changed the transmission oil? If so was it recent? You think correct amount of oil was put? How many miles do you have on the car? No CEL lights right? The burning smell is most likeley the tranny worked real hard (stress) due to the high rpm changes and/or overheated which isn't healthy for a transmission. Also burning smell can be anything but from your description I'm leaning more towards the tranny (low fluid maybe). Surprised it didn't go into limp mode...or did it? Was it ever stuck on 2nd gear?

Glyn M Ruck

I suspect it did go into one of the many 722.9 limp modes which is why it would not change up. See last point on slide.

moonrkr23

hey guys, no cel lights, limp mode? will it come out limp mode on its own and also it has 80000 miles, 2007 c230 automatic, i don't think i put that in original post. thanks. no transmission oil has been changed since we have had it, according to the dealership everything has been done to it. where is the dipstick for transmission?

Glyn M Ruck

There is no dipstick. Level is checked by spill over method at correct temp from beneath. It will sometimes come out of limp mode on reboot but once the condition occurs again it will go straight back there to protect the transmission. I'll bet the transmission has not been serviced.









Read this thread for info & cobble up a syringe to top up.
The fluid & filter must be changed every 39K miles

https://mbworld.org/forums/c-class-w...nsmission.html

moonrkr23

yes it had been serviced and mechanic said it was the control unit in the transmission and theres been a lot of problems with those. its going to run about 1100-1600 dollars to fix. thanks for all the info. mercedes are going back and forth trying to figure it if its a defect or what.

Glyn M Ruck

Conductor plate & speed sensors gave trouble on early units. They are now in the third generation & fixed. Benz only allowed complete replacement of the electrohydraulic unit from Germany originally but now allow conductor plate replacement only by dealers. It is about $1000 job. New conductor plate is about $150 & Benz has stopped selling them & any valve body spares to rebuilders.



This is the conductor plate.

moonrkr23

Thanks Glyn. the mechanic said it is up to mercedes on what they send either the whole part or the conductor plate. so we hope its just the conductor plate. thanks again

Norwichdelta06

did you always have a harsh transmission shifting issue esp going from 1-2-3 gear? Because i brought it to MB about twice already and paid 200 total in dianostic fees to find out it was nothing "tranmission reset" which didnt fix the problem. So if thats my problem and its 1000 dollars I might bring that up to them instead of just getting my fluid changed.. bc they are going to do the fluid change anyway with that part change

04mbc230

The problem is did this issue bring up a code? If there is no code, I don't think they can order this part from MB. MB won't the tech order it without a code showing that it is in trouble.

As for your year model, on another thread, it is said that it comes in one whole piece and the part itself cost close to $1000.

moonrkr23

To Norwich,
the mechanic said it did throw a code but i can't remember the code. no my transmission was running fine up until that day. but later that day it was running fine. the mechanic said it will happen again but that he would reset it for now. i am going to get it fixed when the part comes in. they have had a lot issues with this.we will let you know the code thurs. or fri. when we take it to get it fixed.

Glyn M Ruck

The whole valve body (electrohydraulic unit) is more like $3000

04mbc230

oh... Guess it's more bad news.

clifton001

has anyone had any success with Mercedes Helping them out on this issue? my car goes in tomorrow for the repair.

Glyn M Ruck

Yes. MBUSA replaced Karo's complete valve body FOC on his 350. However there seems no consistency in goodwill help.

LILBENZ230

What is up with this? It is happening more and more to W203s with the 7G. Bad batch of parts?

Glyn M Ruck

Early 722.9's suffered speed sensor problems. Benz had the attitude that dealers should not touch the electrohydraulic unit. As best I can ascertain the real problem was the conductor plate corrupting speed sensor data leading to implausible readings. In the latest generations of the transmission the problems don't occur.

It's strange. The conductor plate was the cause of trouble in early iterations of the 722.6.

You would think by now that whoever supplies this $150 piece of plastic with basic circuit connections on it could manufacture these things reliably.

pa-hawk

Excuse my ignorance on this subject, but which transmission is prone to this trouble and if possible, which model and years? So far my 5 speed is doing OK at close to 80k miles. Should I be keeping my fingers crossed?

LILBENZ230

Your 722.6 5-speed should be fine.

Glyn M Ruck

+1

pa-hawk

Good news! Thank you.

Glyn M Ruck

Just service your 722.6 - fluid & filter every 39K miles or 60K Km's & the transmission is capable of 1 million Kms. Taxi's in Europe & all over Asia do that.

johnand

This whole 7G speed sensor/conductor plate/valve body fiasco is starting to become TOTAL BS, IMO. I had mine go into limp mode once with the speed sensor error. My valve body is the older part number, so it needs the whole valve body replaced and not just the conductor plate according to my local dealer, but I don't buy it. Since my 07 was one of the last off the assembly line, it appears that the problem wasn't fixed for the 07 model year. I would rather have my indy do it, than get raped by the dealer, since MBUSA has told me that I am on my own to pay for the repairs since I am outside of warranty. This is even with my supplying documentation that shows this is a KNOWN design defect.

Problem is MB stopped selling the valve bodies!!!!!!!!!!! They are only available through MB dealers if the proper logs and paperwork are complete and the dealer does the work. You CANNOT buy just the valve body at a dealer, distributor, or online outlet anymore. So, even your indy mechanic that has a proper STAR system to SCN code it CANNOT get a valve body to replace yours. As far as I know, there are laws against this. Since they are failing at such a high rate, and are only available at the dealer, the price is almost $3000 for the unit alone. I had searched parts.com months ago when mine started acting up and I could get one for ~$1200 shipped.

Here is an indy posting about the issue: http://jayauto.wordpress.com/2011/06...-transmission/

LILBENZ230

You're right that it doesn't seem Mercedes could strong-arm you into paying double at the dealer.

I'm sure Mercedes reasoning is that the dealers are the only qualified people to replace this. However, we all know how incompetent MBUSA dealers are - do they even know the 2007 has a 7G transmission?

I'm concerned at the link you posted from that mechanic who says these are "failing so often". Are we getting ready to see a wave of hugely expensive 7G failures as the cars get older?

johnand

I have had a few chats with one of the most knowledgeable MB indy mechanics in the NW. This is where I get a lot of my information. I also have regular conversations with the lead tech at my local dealer. These problems with the 7G are starting to show up in greater numbers and frequency of late. The real issue, is these problems are starting to pop up on 7G equipped cars at higher mileage (outside warranty), and on ones that MB thought they had fixed the problem. It appears that might not be the case. I have also been told the same story as the link I provided, and it appears MB and VDO are in a pissing match of who is at fault. I am not too fond of VDO parts of late. Remember my fuel pump that died prematurely? Yes, it was a VDO part.

Mercedes stance on not supplying the valve bodies is part of their anti-theft policy I can see this on EIS, smart keys, etc, but the transmission valve body