Bad day, 722.6 transmission in W163 stuck very much in 2nd

[clarkmichigan55b]

Don't know if you have seen this 2 part You tube video on ML auto transmission, It may be of help but the sound quality is poor.

 

[tttonyyy]

Wow, his loom is awful. Fortunately no such fraying on mine.
Still behaving itself so just need to fix the weep of ATF it has from the sump seal and I think I'm good - fingers crossed!

 

[hmang]

 

[Jim2]

Brings back a memory.
I've done three of these boxes, and I had an original dipstick which of course I kept for the next car when i sold a previous one (all 722.6 boxes). The dipstick went with the sale of the last car, but ... at the time, there was a Youtube vid giving measurements for anyone wanting to make their own dipstick. I made one at one point out of net curtain wire and marked it up.
Malcolm (Television), now deceased, posted measurements for fluid levels for the 722.6 box. A trawl through his original posts will find them - but be warned, he was a prolific contributor!

There is an alternative. If you really think your fluid level is on the low side, causing your current troubles, then why not add atf in easy stages while monitoring any changes in the box behavior. If you reach a point where it feels better, mark your present dipstick accordingly.

Here's some pics of the aftermarket one that I use, and it works fine. Fluid Temp has to be at at 80c, and the car 100% level. Best method of checking the temp is via OBD reader ( iCarsoft ) as checking it externally via covid type beam is not 100 % accurate. Would be good if anyone who has the trans sump removed, would insert the dipstick and take a pic of it in situ. I've often wondered exactly just how deep does it enter into the sump, and that the diamond is the actual stop point. I'm pretty sure that it is, just I'd like confirmation.

 

[Jim2]

Had the ML270 for 18 months now, sorted the swirl flaps and running 100% biodiesel no problem (aside from having to periodically rebuild the high pressure pump - the head seals deteriorate quickly).

Since ownership it has always "slipped" a bit in 4th, IE overrevved - like a clutch band is slow to grab. More recently it's started to go into limp mode (2nd) reporting "improbable gear ratio", which cleared when stopped and restarted.

Now it's permanently in 2nd. And my expensive iCarsoft MB V2.0 had the screen flicker and die so I can't see what else it's reporting.

I've dropped the transmission pan and the valve body, removed and tested the solenoids (they're all fine, as far as I can see). There was quite a lot of very fine metal sludge both stuck to the magnetic trap at the bottom of the pan, and all over the magnetic sensor that peers up into the gearbox (presumably to sense RPM). Not good for a box that has only done 70k.

Additionally, there was quite an ATF leak past the wiring loom bushing.

I've cleaned it all up, put it all back together (with new bushing), put in new ATF (torque converter flushed via pipe on ATF coolant return). But alas, still stuck in 2nd.

I don't really want to give up on the old girl, but I'm at a loss what to try.

Some photos.

Underneath of box with valve body removed. I assume that the rectangular holes visible behind the circular holes are used for RPM sense. That they're in this position perhaps implies that the thrust bearings haven't allowed the shafts to slide them out of view of the sensors?

Valve body, note the magnetic swarf on the RPM sensors:

Solenoid valves out, each was a few ohms of resistance and I blew through them with an airline

All refitted with new pilot bushing and filter:

More metallic sludge from the ATF coolant return

ATF going in

ATF from torque convertor coming out

" Quote:- More metallic sludge from the ATF coolant return UnQuote"
My God.......how was it even working???? But aside from that, Thanks for a very informative post. Hope it comes right for you.

 

[dieselman33]

Looks like the folks on this thread may be able to help me. I have the W210. I'm thinking about purchasing the Icarsoft MB V2.0. I need to reset my transmission error code so that I can get out of "limp home mode". Does anyone know this device from Icarsoft will work on the W210 transmission? Thanks so much! I'm stuck without my ride :0

 

[Oldspanners]

Looks like the folks on this thread may be able to help me. I have the W210. I'm thinking about purchasing the Icarsoft MB V2.0. I need to reset my transmission error code so that I can get out of "limp home mode". Does anyone know this device from Icarsoft will work on the W210 transmission? Thanks so much! I'm stuck without my ride :0

Contact ukpartsdirect who are official suppliers and run an excellent service they will give you all the correct details.

 

[tttonyyy]

Would be good if anyone who has the trans sump removed, would insert the dipstick and take a pic of it in situ. I've often wondered exactly just how deep does it enter into the sump, and that the diamond is the actual stop point. I'm pretty sure that it is, just I'd like confirmation.

Thank you for the photos, and actually that's a really good idea, I wish I'd have thought to take some photos of the dipstick end when the sump was off - it would give a really good idea of what the fluid level is supposed to cover. My sump gasket leak is now fixed and it's running brilliantly again.

There is most definitely a relationship between sticking in 2nd and low ATF level.

 

[tttonyyy]

" Quote:- More metallic sludge from the ATF coolant return UnQuote"
My God.......how was it even working???? But aside from that, Thanks for a very informative post. Hope it comes right for you.

I think I've had low ATF level for a while thanks to the pilot bushing leaking, I'm sure this has resulted in lack of lubrication and wear. And the fluid was in a terrible state which cannot have helped.

The magnetic catcher grid at the bottom of the sump was overloaded with fine metal and the rest was stuck to the encoder wheel sensors. But despite this, it seems to be fine now that it's got a new conductor plate, new ATF and the loose bolts on the valve block tightened, and in the couple of weeks between taking the valve block out again no more swarf collected.

I remember a transmission tech once saying that it's way more important for transmission longevity to regularly change the ATF for any compatible ATF than it is to use long periods and use manufacturers specific ATF.

 

[tttonyyy]

Looks like the folks on this thread may be able to help me. I have the W210. I'm thinking about purchasing the Icarsoft MB V2.0. I need to reset my transmission error code so that I can get out of "limp home mode". Does anyone know this device from Icarsoft will work on the W210 transmission? Thanks so much! I'm stuck without my ride :0

What year is it?

Mine is 2003 and not EOBD, standard readers can't find anything. I was left to believe only Star would connect, bit fortunately the MB2.0 does everything and without it only a dealer or specialist would have been able to reset the code that had locked the box in 2nd.

I tried all sorts, the ignition cycle with foot on the throttle that people mention, leaving the battery disconnected overnight - none if it helped and I was losing hope.

 

[Oldspanners]

I think I've had low ATF level for a while thanks to the pilot bushing leaking, I'm sure this has resulted in lack of lubrication and wear. And the fluid was in a terrible state which cannot have helped.

I remember a transmission tech once saying that it's way more important for transmission longevity to regularly change the ATF for any compatible ATF than it is to use long periods and use manufacturers specific ATF.

Some people will just change the ATF in the sump when they are doing engine oil changes just to freshen it up between complete ATF and filter changes. Not a bad idea on ageing transmissions.

 

[tttonyyy]

I had an old Mitsubishi where I drained the sump only, refilled, ran for two weeks and repeated - a majority change of the fluid. But back then ATF was a lot cheaper! Fortunately on the w163 there's a very accessible union on the ATF return from the cooler, so could do a "proper" change (which I guess is what a Mercedes garage would do).

 

[tttonyyy]

Looks like the folks on this thread may be able to help me. I have the W210. I'm thinking about purchasing the Icarsoft MB V2.0. I need to reset my transmission error code so that I can get out of "limp home mode". Does anyone know this device from Icarsoft will work on the W210 transmission? Thanks so much! I'm stuck without my ride :0

Hi dieselman I just saw your post on my profile but I'll reply here as well in case you miss my reply:

Here are the menu options the MB2.0 gives for your car, so it may depend when in 1997 it was built:

If you go down the "up to 02/1997" route it just presents scan options, "as of 03/1997" gives the options above.

 

[dieselman33]

Hi dieselman I just saw your post on my profile but I'll reply here as well in case you miss my reply:

Here are the menu options the MB2.0 gives for your car, so it may depend when in 1997 it was built:

If you go down the "up to 02/1997" route it just presents scan options, "as of 03/1997" gives the options above.

Thank you so much for this information and your time!!! Very much appreciated!!