Hi. I did a flush to my e320 cdi last weekend. 313km odometer. This seems to have caused a slipping issue.

After flush I drove 2 days (~450km), no issues, on the 3rd day transmission started slipping after driving 30km. Had the dipstick in the boot, oil level was just a few mm over maximum.
Could hear some weird noises in the transmission when I shut engine off - noise slowly faded away in a minute or 2. I thought it was foaming and presumed I had to lower the oil level.
Stopped several times on the way back home as I could drive only 5-10km before it started slipping again.
Removed roughly 500ml oil. Drove fine for ~150km and started doing it again. Now regardless of oil level I can drive like 5-10km before it starts slipping and I have to turn off the car and wait for a couple of minutes.

I did the flush from the front cooler hose and I flushed it 3 times 3L out 3L in. that's the only thing I did, didn't touch the oil pan or oil filter as I replaced the oil filter and stuff a month before.
Other stuff done to the transmission before (mostly 10's of thousands of km ago) - sonnax sleeve kit, new TCU (conductor plate), new plug (connector), oil & filter changes. Been doing these things to find a cure to the jerky cold shifts.

Any suggestions more than welcome. Did I kill this old 722.6 ?

 

Did you change the connector? Otherwise it's probably the conductor plate.

https://www.fcpeuro.com/products/mer...tor-2035400053

 

Hi. Both have been replaced a year ago. Do you mean either of them got damage because of the flush?

 

To describe the slip more in detail:
While driving can feel a slight jolt when the lock up disengages. Transmission is then slipping and the longer I go the more it slips, so quite quickly I am basically in neutral.
When I stop and change gears to D, R, It does a very harsh jolt.
If I turn the engine off and wait for only a few minutes then I wont get a jolt when selecting D and when driving it shifts harsh and gets stuck in like 1st, 2nd or 3rd gear - wont shift up of down after that.
If I turn the engine off and wait for 5-10 minutes, then the car will drive normal for a quite varied amount of time - sometimes it can start slipping only after a few hundred meters, sometimes I can go like 15 minutes.
Seems to start slipping earlier when I drive faster (100kmh+).
And of course I can go the longest before slip when the car has sat overnight and fluids are cold.

Overall seems like something goes wrong as transmission fluid pressure gets higher.

 

Probably not, but diagnosing problems from feel will probably not lead to a solution.
First, what was the reason for the flush? Were there problems that the flush might fix?
Next, can it be assumed that the transmission fluid was one of the approved products on the BeVo?
Then, did you try a reset of the TCM?
To really determine what might be going on in the transmission, a scan tool capable of reading transmission trouble codes and data is needed. Here is an overview of 722.6 operation and diagnostics:

https://www.transmissiondigest.com/t...hift-strategy/

Here is a video of the reset procedure. There are many others available:

https://m.youtube.com/watch?v=gYVAOr6uJbI

Good luck.

 

Agree, pull/clear codes see if they return. No codes, try cleaning conductor plate/solenoids/etc. see attachment.

 

I had a similar nightmarish experience on my 08 E350 722.6 tranny flush. I changed the conductor plate, connector, cleaned out the valve body, installed the Sonnax sleeve kit, and flushed through the front cooler hose as you did. And of course, I experienced erratic shifting that would leave the car in limp mode, but turning the ignition off and back on would get me out of it until it inevitably slipped again.

I recall getting differing error codes, one had to do with a solenoid so I even dropped the pan again to change all of them out with new solenoids, plus I replaced the connector, conductor plate, and performed another flush (fortunately under FCP Euro's lifetime warranty!) - yet nothing changed and I would even get solenoid codes still. A consistent code I was getting was one that stated the transmission ratio was impermissible.

In the end, the culprit was the fluid level. You didn't specify exactly how you measured your oil level so I hope that this is the solution to your problem. I plugged in my scanner to measure the transmission oil temperature and went for a short drive until it reached 80 C. Then I shifted through all the gears, including side to side from 1-5 and 5-1 (not sure if that's necessary but I did it anyway), waiting around 5 seconds between each switch. Then I measured the oil with the febi dipstick and found that it was underfilled below the 80 C line. I poured more oil, drove a few minutes, and checked the level to find it was around 82 C now. I turned the car off, cleared my codes, turned the car on, and decided to test it on the highway. I almost cried on that drive when it shifted smooth like butter and it has not slipped once since then, 20,000 miles ago!

I also wanted to add some other details that could be helpful: Before my flush, I was not experiencing any tranny leaks, slipping, or any other issues at all, just wanted to do some maintenance. I also checked my connector lines to ensure that there was no oil on or inside them. When performing the valve body clean and Sonnax install, I soaked everything in oil before reinstalling. I used Liqui-Moly ATF 1600.

 

Thanks for suggestions everyone! Problem is now fixed, here is what it was:

Context: Before this issue one of the rear abs sensors/abs rings was dead. And I mean dead-dead, 100% the time the abs/esp/brake light was on. I had the new sensor, new ring and a time booked to get it replaced. Car drove fine with one dead sensor, only no cruise control.
That sensor/ring replacement was only a few days after the transmission problem, so I had to cancel the booking for the replacement (workshop ~80km away).

I ordered a icarsoft diagnostics tool to see what could be up with the transmission and this is what I got: one rear abs sensor was out (the one I knew about) and the other rear sensor had a historic error (intermittent, likely dying).
So now everything was clear, I knew that the transmission wouldn't drive if both rear abs sensors/rings are out.
I changed the ring and sensor myself and took it for a test drive - no lights on the dash for 20km (both rear sensors working fine), then got the same abs/esp/brake error, but this time the transmission kept working fine because the other rear sensor was functioning.

So there you have it, seems like the second abs sensor/ring dying RIGHT AFTER I did the flush was just a big coincidence and the transmission had nothing to do with this. And because the other rear abs sensor was already out, I didn't get any new errors on the dash...