190e automatic transmission 722.4 valve body part numbers

[Mercster]

Hello,
I have a 1992 190e 2.0L which has stopped engaging reverse gear. It has only travelled 60k miles (100k km) and is strong in all forward gears. Reverse gear has engaged intermittently since failing and on both occasions has been also been strong. As a result it seems that the problem may not be within the drive train of the gearbox itself but possibly with the switching mechanism or valves.


I hope that the problem will be solved according to the attached technical note which points me to the valve body, however, I have been unable to find the required part numbers and am wondering if anyone out there can help with part numbers or another suggestion as to how I could track them down.


The parts are called;
"Accumulator Switching On Control Valve",
"Accumulator Switching On Control Valve Spring",
"Accumulator Switching On Piston seal ring"
"Accumulator Switching On Piston"
These parts are shown in the attached diagram.


The transmission number is 722400 0 3252557.
Any assistance would be most appreciated.

[MCallahan]

Hope this doesn't ruffle admin feathers, but the second comment on this thread has three links to the factory transmission manual. The first one has troubleshooting guides and a full explanation of what valve does what in each gear.

http://www.benzworld.org/forums/showthread.php?t=1515129

[Mercster]

Thanks very much MCallahan. I have downloaded the 3 documents and will spend some time working through them. Most appreciated !

[MAVA]

Better than 95% of the time it is the small reverse piston lip seal. It hardens. Then the jumpy and chatters. Then when the seal tears one looses reverse hot or cold.

Photo 7 of this thread shows you the seal-This is how you get to it-It is the same process for 722.3-722.5

Photo 10 shows all the parts you should replace, but you should replace all the springs too.

722.5 transmission oil pump rebuid DIY - Mercedes-Benz Forum

Here is a thread on the fix too:

no reverse / jerks in reverse when cold - Mercedes-Benz Forum

Some more info, and post 5 has everything you ever wanted in transmission repair:

Gearbox 722.368 repair manual / tips - Mercedes-Benz Forum

All the best,

Martin

[slk230red]

Welcome to the W201 no reverse club. My '93 2.3 reverse just went out at 117K miles. All forward gears work perfectly, but reverse works good enough when cold, but not so good when hot.

Good luck, I hope you post if you find a fix.

[MCallahan]

Oh, and word to the wise.... NEVER let a cloth or paper towel, wiper or anything touch an automatic transmission part. Don't even lay them on a rag, lay them in a new clean plastic or aluminum pan. Do not wipe them with a rag. For cleaning, bathe in a solvent (mineral spirits or a spray type cleaner like CRC brand MAF cleaner) and blow off with compressed air. Bathe in trans fluid before putting back in.

I worked for a guy who had a legendary trans rebuild shop and that's where I learned this secret of transmission work. His transmission bench was a big shallow stainless steel sink with a parts cleaner pump circulating fresh ATF continuously. Everything was cleaned elsewhere and then when surgically clean, assembled in that bench/sink. It only takes a few little wads of lint, cat fur, paper fibers, etc.. to clog up a valve or check ball, which will cause no end of grief.

[Mercster]

Mava,
Thanks for the information you posted a while ago. I am about to start this project.
All the best
Mercster