Sliparama

I don't consider myself a tranny guru but may have some info, posted this pdf a while back. A sample from the manual concerning this may be:
"Incorrect modulating pressure, Modulating pressure control valve or pressure relief valve is sticking" B

 

I don't consider myself a tranny guru but may have some info, posted this pdf a while back. A sample from the manual concerning this may be:
"Incorrect modulating pressure, Modulating pressure control valve or pressure relief valve is sticking" B

As I understand it is vacuum modulator, what I did is just unplugged vacuum line to see if shifts become normal and eliminate slipping. Granted shifts became a little better but the slipping was not eliminated. Also checked the modulating control valve and it is moving easily... I don't really know how to see if it is still good or bad, but visual inspection it looked fine. Running out of options here:crybaby2:

 

Firstible, you should change the ATF. It should have red color. Black means overloaded etc.

 

I will do the ATF change; however I really don't think that dirty fluid will cause this much slipping. Right now the valve housing is on my table being disected and cleaned. I have found a strange metal piece in it which is probably whats causing my symptoms. All i have to do is find where that piece broke off.

If anyone has suggestions what else to check while my transmission is open I would really appreciate it.

 

Picture of offending metal piece may help us.

 

Try this.... it's from a 722.3 and 722.4 book.

 

Check the fluid level with engine running and a working temp ie 80c approx. But was the Transmission slipping when you first got the car?

 

Is there a location to install a manual pressure guage in transmission? Sounds like low main pressure. Or, completely different matter, damage inside torque converter-slipping lock-up clutch, if it uses one. I haven`t researched this trans at all, just thinking out loud in the field at work.

 

UPDATE

Okey, so I reassembled all the valve body and put it back in the transmission. B2 band was a little out of spec so I put in the new thrust pin (only .8mm longer). Refilled with new fluid and took it for a test drive.

Reverse is good, first gear is good, second gear(what second gear??), third gear good, fourth (what fourth??).

2nd gear slips very very badly or just usually shifts from 1-3, skipping 2.

4th gear is not there, not ever slipping, just neutral.

I mean seriously WTF?? :crybaby2:

Need help, ideas appreciated.:bowdown:

 

Maybe you messed up something in the valve body. From my understanding the valve body is the "brain" of the transmission. This is what sends oil pressure to various pistons to engage the different gears. Can you run to the junkyard and grab another valve body and try it? By the way from experience I know that a valve body out of a 722.3 will work too so any W201, W124, W126 should work and there is always a few of those in the junkyard.
When my car lost the reverse gear I experimented with stuff like that.
Here is my posts:
http://www.benzworld.org/forums/w202-c-class/1480338-so-your-car-wont-go-reverse.html
i didn't have any slipping problems though. So my post might not help much.

good luck

 

Don`t know if junk yard will part with valve body alone. May have to buy whole trans from them to get it.

I do agree that you have a valve body problem. Just my 2 cents

 

valve body

I know it sounds like the valve body problem, but I didn't mess anything up. All the valves were taken apart and put back in just the way they should be, I even had a repair manual with me to double check.

I really don't know any good junk yards in Illinois, all the ones I know have really old American cars and that's it.

 

I know it sounds like the valve body problem, but I didn't mess anything up. All the valves were taken apart and put back in just the way they should be, I even had a repair manual with me to double check.

I really don't know any good junk yards in Illinois, all the ones I know have really old American cars and that's it.

It is possible that you put one of the balls back in the wrong place inside the valve body.

 

You have picknpull junkyards in illinois. Go to one of those Pick-n-Pull Home
they will sell the valve body for $20 and in my experience the one here in salt lake always has a few W124 or W201s and W123 sometimes. I have a few transmission PDFs which show the valve body taken apart. Let me know if you need a PDF.

 

Modulator Pressure

If you have slipping in all gears one of the first checks is Modulator Pressure. BTDT! The Modulator sets one of the key internal operating pressures of the transmission. Here's a thread on my discovery of all this some years back. Note: this procedure only applies to the older Hydro models 722.4 and earlier.

http://www.benzworld.org/forums/w202-c-class/1380730-transmission-lurching-4.html

Besides that adjustment the Bowden Cable adjustment on the Throttle Body linkage is also important to set the upshift points in relation to throttle position.


Good Luck!:thumbsup:
C as in 220

 

Solved

Well I know this thread is old but I hate to leave them unfinished.

I got tired with all this cleaning of valve body and finding any parts that may have gone wrong so I just said screw it and bought a new "old" transmission.

I called a few junkyards around me and finally found one for $300 that was taken from c220 with 100k miles. Trans oil was red so I took it as a good sign.

I changed the transmission in my garage over a weekend without any rushing. Most of the time was spent going to my local tool store and buying all kinds of extensions for transmission bolts. If anyone is debating over changing the transmission on their own I say go for it... fairly easy DIY job if you have few friends to help you with removing and putting it back because it is heavy. I had no transmission jack or any other special tools and managed just fine.

Few words of advice and/or caution:
When putting the transmission back, make sure the torque converter is fully seated in the transmission or you will have clearance problems. Make sure the vacuum lines are out because most likely you will press them between trans and engine so just take them out they are easy to put back from top. If you somehow manage to to put the top bolt in then kudos to you otherwise you don't have to put the top bolt of the transmission back in, don't worry you are not driving a 600hp Corvette and the transmission will be just fine. Same goes for a torque converter, I broke 1 bolt and did not feel like taking the transmission out so I just left it as is with other bolts secured.
Now the car drives just fine and shifts excellent. :thumbsup:

Pictures attached so you can see my work conditions

 

Good Job!

A new 722.4 Guru is made!:bowdown::bowdown::bowdown:

Good Luck:thumbsup:

C as in 220

 

I wouldn't consider myself a guru yet but I sure did learn a lot. I'm just happy I pulled it off myself, the shops I went to wanted ridiculous $$$ for the labor, after changing the transmission myself I don't see what the big deal is...

 

Wow, some serious jacking and support action there. Did you opt for new flex disks and a center bearing as well. Glad your back on the road. B

 

Yeah I just used whatever I had to support the car. I had jackstands but they are just horrible.

My old flex disc was gone but the other flex disk that came attached to new transmission was good. My center support bearing was good as well so I left it as is. :thumbsup: