Gearbox woes!

[bigp271]

Evening all.
Firstly let me apologise for not being active this last while.
I had planned to participate more but things have been rocky of late.

Anywhoo, after 2 misfires with the parts cannon I finally managed to get my w220 on Star and the diagnosis wasn't great! It would appear that after 69000 miles my 722.6 box has had it.
My question is, will any 722.6 box from a Merc fit straight in?

Many thanks in advance

Paul

 

[AMGeed]

Has to be exactly the same . A 722. 6** to match your gearbox.
Don't worry about not being active here. People come and go all the time.

 

[bigp271]

Thank you for the reply mate.
That'll be a hoot trying to track down a good numbers matching box!!

 

[AMGeed]

^ Is your gearbox that bad it can't be rebuilt?
No guarantee a used gearbox doesn't have faults.

 

[Smiley]

Are you 100% sure that it is the gearbox? They are usually very robust indeed.

 

[bigp271]

After a new conductor plate and known good tcm of the same part number we still get transmission has implausible ratio fault code.
It's on a present code whilst moving. The car starts off fine then it feels like it jumps into neutral or the pressure drops.
I had thought I'd found the issue when I found the original tcm about quarter full of trans fluid!

 

[Petrol Pete]

The internet is full of 722.6 content, most of it good , i:e it's rare that the trans is toast and they are re buildable and kits exist to repair/modify the valve body. Unless you buy a brand new one you might just be getting into more trouble.

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I have posted this (rather long) video before , but it is very informative . the valve body is removable with the transmission in the car and refurb kits are available.

https://sportlichleicht.com/info/transmissions/722_6

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PS .My 16 year old 722.6 transmission has 150K miles on it ...and it has been dealing with the output from a 5.4 V8 AMG engine for all of that time.

 

[bigp271]

So it looks like it's the shift from second to third that causes the box to drop pressure.
So it's a rebuild or a replacement box.
Anyone fancy a low mileage S320 V6 that requires a wee bit of tlc?!

 

[Petrol Pete]

Did you watch the videos and see that diagnosis in there ?

 

[bigp271]

Did you watch the videos and see that diagnosis in there ?

No mate I thought they were screenshots!! I'll watch them when I get home from work!

 

[Petrol Pete]

No mate I thought they were screenshots!! I'll watch them when I get home from work!

The first one is VERY long , but it's almost all you need to know about this particular transmission . Alex at legitstreetcars explains even more.

 

[bigp271]

I'd seen the legit Street cars one before, it's always a good watch.

The other one I'll need to watch a few times to fully absorb it!!
I still can't quite get my head round the trans needing replaced/rebuilt.
I'm wondering if the problem lies in the valve block.

 

[Petrol Pete]

Well , taking the valve block off and refurbishing it is a lot easier than replacing the transmission . BUT it might not cure the fault....but at least then you have a rebuilt valve body that you can install on the next trans , or obviously leave on your gearbox when you have it re built.

Bit of a 'scattergun' approach to finding the fault, I would keep trawling the internet for 722.6 content . You mention finding the T/C 'about a quarter full of ATF...' , How much were you expecting to find in there ?

 

[bigp271]

Well , taking the valve block off and refurbishing it is a lot easier than replacing the transmission . BUT it might not cure the fault....but at least then you have a rebuilt valve body that you can install on the next trans , or obviously leave on your gearbox when you have it re built.

Bit of a 'scattergun' approach to finding the fault, I would keep trawling the internet for 722.6 content . You mention finding the T/C 'about a quarter full of ATF...' , How much were you expecting to find in there ?

It was the TCM , Transmission Control Module I found full of fluid after had wicked up the harness.
My current thinking is to fit a known good, used box as I need to sell the car. Then I can get my box refurbished later on for a different project.
There's just something nipping at me saying I've missed something.

 

[Petrol Pete]

Sorry , my mistake , I read your comment as TC quater full of oil , not TCM

 

[meeshy]

Well , taking the valve block off and refurbishing it is a lot easier than replacing the transmission . BUT it might not cure the fault....but at least then you have a rebuilt valve body that you can install on the next trans , or obviously leave on your gearbox when you have it re built.

Bit of a 'scattergun' approach to finding the fault, I would keep trawling the internet for 722.6 content . You mention finding the T/C 'about a quarter full of ATF...' , How much were you expecting to find in there ?

Hello there, I am in the middle of the same situation, and wondered if a solution has been found. My codes are P2069 and P2502 read via a Solus Pro, I have changed the conductor plate twice, replaced the solenoids, replaced filter, replaced connector and swapped the TCU, although I reinstalled the original as the same fault prevailed. The harness has some ATF wicking but TCU was dry. Week before these faults showed up I changed the Differential and both rear ABS sensors. Solus pro shows both sensors operating normally. My thinking was that there might be a connection between the speed sensor on the conductor plate and the rear wheel speeds. I am also concerned the replacement diff has a different ratio, hence confusing the information the ECU and TCU are expecting. Anyway next step is to remove the valve body again, this time I will completely dismantle and clean, and fully test the solenoids. Will update in the future. Best of luck to everyone.

 

[Petrol Pete]

Im no expert on this , but if the diff ratio is 'wrong' the rear wheel speeds won't match what the TCU is expecting at any given time .

What diff went in there ? from where ?

 

[meeshy]

Im no expert on this , but if the diff ratio is 'wrong' the rear wheel speeds won't match what the TCU is expecting at any given time .

What diff went in there ? from where ?

First job when the rain stops is to double check the part number. Unfortunately I did not double check it myself, before installing. I supplied the Registration and VIN to the seller. It supposedly came from a W209 CLK 320.

 

[AMGeed]

First job when the rain stops is to double check the part number. Unfortunately I did not double check it myself, before installing. I supplied the Registration and VIN to the seller. It supposedly came from a W209 CLK 320.

722.618 is the code you are looking for.

 

[meeshy]

Help folks, I have now checked the part numbers on the differential. My original is 210-351-33-08, the one I installed the week before I started having gearbox issues is A203-351-09-08. The casing part number is A210-351-08-05 and is the same on both differentials. The codes I have are P2069 and P2052. I have changed the conductor plate twice, replaced the solenoids, replaced filter, replaced connector and swapped the TCU, although I reinstalled the original as the same fault prevailed. The harness has some ATF wicking but TCU was dry, and I have cleaned with correct electrical contactor spray. I changed both rear abs cables as well.
So my current theory is that the changed differential is a different gear ratio. This is messing with the info being exchanged by the ECU and TCU hence the implausible speed DTC, and failure to change from 2nd to 3rd. I checked the resistance of the solenoids via the TCU cable and all were in spec.
Can anyone advise from the part numbers if the old and new differentials have the same gear ratio, and if they are different can this throw up a DTC.

722.618 is the code you are looking for.

Thanks for reply, I believe you are referring to the gearbox, I am trying to work out what is happening with the change in differential, and I am referring to the actual part numbers stamped on the casings.