722.6 Gearbox Slipping 1st/Reverse - conductor plate or something else?

[cbmsys]

Hi Guys

There's a lot of info about issues with the 722.6 gearbox, but all seem to mention ranging/slipping when changing gear. Mine slips in 1st/reverse, sometimes it will rev up and drag, other times it will judder badly, or slip and engage squeaking the tyres. Only does it when moving off, and normally when under load. If you're gentle with it, it usually moves off ok. Doesn't do it if you change down into first from 2 and floor it, and it is fine in all other gears/changes. Very rarely it will go into limp mode. Anyone know if this is a conductor plate/oil in plug issue, or something else entirely? I do know the history of the car (E270) and it only had it's first oil change in the gearbox at 170,000 miles, (now 186k) when it was presenting problems with engaging gears and slipping. Short of doing another filter change and flush, I'm out of my technical ability with Auto boxes.

TIA
Alex

 

[zipdip]

Well Alex,a first gearbox oil change at 170,000 miles is as you know far too late,I suspect your box has started to let you know it is on it's way out.of course check the connection for any oil ingress,you do not say where you are,maybe somebody can suggest a decent indy that can check it out.

 

[W1ghty]

Yep it’s Indy time

 

[JWood3]

I had my 722.6 box slipping and going into limp as soon as it was warm. Wouldn’t even get to the end of the drive before dropping into neutral. I drained the box and changed the conductor plate, connector and filter. In 220,000 miles I don’t think it ever had a service as the filter and valve body were jammed solid with clutch material.
I pretty much thought that was it at that point, but £60 for the conductor plate kit and £30 of fluid was worth a shot.Cleaned everything out and refilled to the correct level and it now works perfectly.
if you can do the job yourself you have very little to lose by giving it a shot. You can’t make it more broken....

 

[amazighman]

Do an oil change and make sure the level is spot on and take it from there.

Also check for any fault codes stored

 

[bob6600]

Seeing as it's only done 16k since the last oil change, I would check the level at the correct temperature. As said, the level could be incorrect. Normally I would suggest changing the oil but in this case if the level is incorrect, ensuring the correct level could cure it. If the level is correct, the 'box will need to be investigated which could mean another oil change anyway. A good Indy with STAR/Xentry can check the 'box for faults and hopefully diagnose.

 

[alabbasi]

In my experience, a conductor plate would not cause the gearbox to slip. I'd flush the fluid and use fluid that meets 236.10 specs which will put new fluid in and also allow you to inspect the pan and the old fluid. If it smells cooked, it might be time for a rebuild.

 

[W1ghty]

In my experience, a conductor plate would not cause the gearbox to slip. I'd flush the fluid and use fluid that meets 236.10 specs which will put new fluid in and also allow you to inspect the pan and the old fluid. If it smells cooked, it might be time for a rebuild.

236.14 is backwards compatible and is the choice now

 

[Bert_W164]

Check the trans oil level, given it was left so late, wishful (and doubtful thinking here) may be another flush will clean out any crud, make sure the whole system including the torque converter (if applicable) is drained too and see how you get on.

Although it's sounding like your box is buggered, I had a clk230 which didn't have a oil change in like 150k, however a drain + running extra oil to flush the box sorted it. Though I didn't have any symptoms that you're describing, good luck I hope it's easy to sort!

 

[amazighman]

Mine was supposedly changed by a specialist as per service history , However after I bought it it drove like shit , found out it was incorrect fluid level.

Ideally you start with least expensive fixes and work ur way up , a flush would be good start point

 

[cbmsys]

Well today I checked the level (low) and dropped the pan. The fluid is a very light brown, doesn't smell burnt. Changed the filter and cleaned the pan, when you wipe your fingers on the bottom of the pan they come away with black, so it's definitely dropping filings into the pan. However when i released the electrical connector I got a faceful of ATF.... I'm presuming that means I need a new conductor plate. It hasn't worked its way up the loom, so it isn't getting past the o-ring on the plug. Elected not to waste another 9 litres of ATF flushing it, as it looks like more work is required.

Fitted a new filter and filled it up, (Titan 4134) I guess we will see if it improves or not.

 

[W1ghty]

Well today I checked the level (low) and dropped the pan. The fluid is a very light brown, doesn't smell burnt. Changed the filter and cleaned the pan, when you wipe your fingers on the bottom of the pan they come away with black, so it's definitely dropping filings into the pan. However when i released the electrical connector I got a faceful of ATF.... I'm presuming that means I need a new conductor plate. It hasn't worked its way up the loom, so it isn't getting past the o-ring on the plug. Elected not to waste another 9 litres of ATF flushing it, as it looks like more work is required.

Fitted a new filter and filled it up, (Titan 4134) I guess we will see if it improves or not.

Did the sump have a magnet in it ? Did you measure the level hot with engine running on a level surface , gearbox in P , with a dipstick ?

 

[cbmsys]

Yes, the sump has a magnet. Fairly clean, not much debris on it, no large chunks or splinters. Just the black residue. The box is now properly topped up and seems to be working much better. I don't want to rag it just yet to see if it's going to give problems, but it isn't slipping. Been into work today (20 miles each way) and the level was just below the hot mark when I got back tonight. Needed a about 200ml to bring it up to the top. Before I changed the fluid it was down the bottom of the stick even when it was hot, so this may have been the sole cause of the issue, as it would have been way down when cold.

 

[W1ghty]

Yes, the sump has a magnet. Fairly clean, not much debris on it, no large chunks or splinters. Just the black residue. The box is now properly topped up and seems to be working much better. I don't want to rag it just yet to see if it's going to give problems, but it isn't slipping. Been into work today (20 miles each way) and the level was just below the hot mark when I got back tonight. Needed a about 200ml to bring it up to the top. Before I changed the fluid it was down the bottom of the stick even when it was hot, so this may have been the sole cause of the issue, as it would have been way down when cold.

That is all sounding very promising buddy

 

[zipdip]

Yes you may well have got a result.

 

[markmifsud]

I watched @BlackC55 do my ATF change and once he had the pan off he gave it a full scrub to remove all of the old residue. I guess there are Good Indies and Excelent Indies.

@BlackC55 says the Pan must be imaculate before replacing.

HOW TO: change the automatic gerbox oil and flush on a 722.6 'box | HOWTO

Here is my how to on an ATF change on a 722.6 box. There are loads of pics. First pic of the car in question a E320 W210. Make sure the engine is hot. At least a 20 min road test

forums.mbclub.co.uk

He did a write up on the ATF change with the 722.6 box here

HOW TO: change the automatic gerbox oil and flush on a 722.6 'box | HOWTO

Here is my how to on an ATF change on a 722.6 box. There are loads of pics. First pic of the car in question a E320 W210. Make sure the engine is hot. At least a 20 min road test

forums.mbclub.co.uk

 

[cbmsys]

I watched @BlackC55 do my ATF change and once he had the pan off he gave it a full scrub to remove all of the old residue. I guess there are Good Indies and Excelent Indies.



Oh believe me, you could eat your dinner off that pan after I'd cleaned it. And the magnet too.

 

[cbmsys]

Latest update: Box is still losing fluid. Remembered a post about the cooler lines, and lo.... leaky

Now I'm hoping I can get the old lines out of the radiator, and undo the couplings. Otherwise this is going to turn into a very expensive repair...

 

[219]

Seeing as it's only done 16k since the last oil change, I would check the level at the correct temperature. As said, the level could be incorrect. Normally I would suggest changing the oil but in this case if the level is incorrect, ensuring the correct level could cure it. If the level is correct, the 'box will need to be investigated which could mean another oil change anyway. A good Indy with STAR/Xentry can check the 'box for faults and hopefully diagnose.

My other question , since it was apparently OK up to the service , and now giving issues are - was it refilled with the correct fluid ? Is the level now correct ?

It may be needing stripped down and the solenoids needing thoroughly cleaned out if not done at the service ...

 

[cbmsys]

My other question , since it was apparently OK up to the service , and now giving issues are - was it refilled with the correct fluid ? Is the level now correct ?

It may be needing stripped down and the solenoids needing thoroughly cleaned out if not done at the service ...

It was giving big problems, which is why I changed the oil/filter around 170k. I was unable to do a full flush at the time, and did say we would need to drain and flush properly shortly. Needless to say, It was some 10k later when it came back, this time for a failed rear brake line. Maintenance was not the previous owner's priority list, it was more a case of calling me to sort it out when it was un-driveable. He decided to get rid of it and offered it to me for nothing when the brakes failed again (other side this time)

I'm now using it as a daily driver (!) and it seems to be fine until the level drops. I guess its losing about a litre every 1000 miles at the moment. The fluid used was/is Titan 4134 (I bought a 20 litre drum to change the oil on my now written off CLK320-722.9 as well). I am currently keeping a refill bottle and the dipstick in the boot at the moment.

Long term, I need to check the pan and see how much has shit has developed over the last 1000 miles. If it's bad then I will fit another box, if not then I'll carry on with it after sorting out those pipes. I don't mind spending a few quid on getting it back into good condition, as it is a really nice car when it's running right.