Transmission issue
 

Hi Folks, have a bit of an issue with the tranny on my lovely convertible 6. She has done 147000 Kilometers and the other night while driving out doing about 30mph just dropped straight into neutral, ie still in drive but engine just revving. pulled onto the side and shifted through the box but still no joy. shut her down and started up again. no warning lights. found the gears and off again. got about 300 yards up the road and the same thing. tried to drop out of drive and use the side shift to change the gears but the dash indicator stayed in D. getting underneath their is traces of tranny oil but not much at all. tried a couple of times more and the same thing. Would engage for a while then just slip back in neutral. Engine check light came on and drove it to a friends garage and pulled codes P 2500, 2561,2562,220A, and 2560. These relate to the transmission. The next set were P2069 and 2066 which were stored in the ETC EGS control unit (P0730 and 0715. I added 1 litre of fluid in the tranny to get home ( some 40 miles in the counrty)On the trip back it done the same thing 5 times with the longest stretch being around 15 miles before it happened again. I have tried to buy the merc dipstick but there are none in the country and will take some 2 months.
Firstly can you give me the distances of the level marks on the dipstick so i can check the level correctly.
Secondly we have the same problems as you guys with no one wanting to work on these fabulous cars so any ideas would be greatly appreciated.
Thanks heaps
Cheers
Paul

Re: Transmission issue
 

Sounds like very low fluid, or a bad conductor plate to me.
You can order the dipstick from eBay :
Look here to order it, and get the measurements you requested :
https://www.ebay.com/itm/AUTOMATIC-T...-/282813794064

for the conductor plate :
https://www.ebay.com/sch/i.html?_fro...plate&_sacat=0

Re: Transmission issue
 

Try this for oil depth.CLICK

Re: Transmission issue
 

Thanks for replies chaps, Its now making a bit of a whinning noise, Oh dear its beginning to sound expensive !

Re: Transmission issue
 

What was the outcome?

I just had my transmission serviced this week and today it did the very same thing you mentioned above.

Re: Transmission issue
 

Mine did something similar a few months after I bought it. When I would hit it hard and then let off, it felt like it shifted into neutral and wouldn’t shift back into drive until I stopped and put it in park. Then it would drive normally. Turned out, I was low on fluid because the conductor plate connector was leaking. Filled it up and ordered a new connector. Went to install it and broke the screw. Ordered a new conductor plate (Ebay) and it came with a new connector. Installed and it was stuck in limp mode. Got fed up and took it to a trans shop. He replaced the conductor plate and connector with new Mercedes parts and all is well. Long story short, low fluid. Why is the fluid low?

Re: Transmission issue
 

The 722.6 / NAG1 is a relatively robust transmission, and rarely anyone has any major issues with them other then the mentioned conductor plate connector seal, and the odd conductor plate contact issue. Please let us know the outcome of the diagnosis as i am curious what happened. If it did infact run low and fluid, one of the fail safes is to drop out of gear to prevent clutch pack wear and burning as it is not able to sustain proper internal pressures. The fact that you kept on driving on it could of most likely toasted the transmission. Which is not ideal, but.. im assuimg C32's and SLK 32's were sold in Australia? so a used 722.6 from those should be applicable.. I tried to find the proper 722.6xx designation, but i cant find it listed.


Edit.. looks like 722.641 is the model you will need to replace the trans in the Xfire tied to the M112.961 engine, if unfortunately you have to go down that route.


One thing that i saw happen that caused erratic transmission behavior was bad contacting inside the shiftier assembly. probably due to a split drink. A quick disassembly, and clean resolved the issue of intermittent limp mode

Most of the stuff i work on for fun are the 722.3 trans found in the older classic Benz, but i have done alot of homework on the 722.6 as im planning to do a M113K+722.643 swap into my 560SEL when i have time, with alot of built up internals.