Transmission won't shift

[5by5]

Hi:

I'm wondering what's up. Everything working fine. Park the car (190 190e 2.6). Return start car, back out, shift into forward. Nothing.

Go back to reverse, nothing. No RPM drop. No sign of anything happening.

Fluid OK, normal color. Linkage moving OK. In Park, the car won't move.

Where do I start with this?

HH

[5by5]

OK, research time I guess.

I understand a broken brake band for forward or reverse can cause the symptom (no go) but it seems unlikely I'd loose the brake bands for BOTH forward and reverse at exactly the same time?!

Everyone talks about changing fluid/filter, but can a clogged filter cause the tranny to go from perfectly normal to absolutely nothing in the time it takes to shift fro reverse to forward?

Anything else--torque converter problem perhaps?

Thanks-HH

[5by5]

Talking to my self--

I found references to some possible causes for "no go in any gear" (arranged from not too bad to really ugly):

1) Check modulating pressure adjust. Check modulation pressure control guide for easy operation.

2) Check vacuum line from intake manifold to vacuum capsule for passage.

3) Check working pressure whether too low or none:
Disassemble and clean shift valve housing, make sure working pressure control slide operable and exchange shift valve housing if required
4) Remove and check primary pump (this is ugly).

Does anyone have any experience with these?

Thanks!
HH

[MTI]

Clearly, you should be starting at the very simple and work up through the harder/expensive. You seem to have ruled out the fluid level, which is the cheapest.

Next would be the physical connections, including the shift linkage and the vacuum line to the modulator.

After that, you're looking at pressure testing the internals, which will require the gauges and fittings. That might best be left to a shop.

[danwatt]

So there is absolutely no hint of the car recognizing it has been put into drive or reverse? Sounds like a mechanical issue with the linkage, but you said you put it into park and park engaged so that must be fine. Drop the pan and take a look around, something this catastrophic should have some obvious evidence.

[5by5]

Yes, that right. Moving the selector has no effect at all. No rpm or sound change. No movement of the car.

I thought at first the shifter link might have gotten disconnected but I got under it and the link from the shifter to the side of the tranny is moving. It is also moving the arm on the side of the tranny. I guess the arm on the side could slipping on the shaft--haven't looked at that yet. Probably have to remove the mounts and lower the tranny to see better. On second thought I'm pretty sure the arm is moving on the shaft because going to park will lock the drive wheels.

I guess I'll lower the tranny next. That would give me access to the vacuum modulator as well--probably the nexxt thing to check. I could also check the vacuum line then but I'm thinking if the line is open or clogged I might expect hard shifts but something still ought to happen.

No AT fluid coming out the top of the vacuum line so I don't think it's the diaphram in the modulator. Maybe the thrust pin in the modulator is damaged or stuck--could that reduce the AT fluid pressure below the point of operation?

Thanks for helping me think through this.
HH

[dineshh]

Just loosen the engine mounts from the bottom, split the fan cowl in half and rock the engine from the sump after removing the tranny cross member and the mount. The valve block comes out easy and you should be able to see a lot from there.

Good luck.

[5by5]

Thanks, Dinesh. I seem to remember your name from some earlier threads on transmissions.

Good advice on the engine mounts and fan shroud.

I'm much obliged to everyone for positing.

Hal

[dineshh]

Hal,
When I did mine, I refused to give up knowing there may be a cheap fix hiding in that complicated mess.

Google was my friend and this manual helped:

http://www.w124performance.com/docs/...722_repair.pdf

[5by5]

Hi Dinesh:

Thanks for the link to the PDF--that's by far the best online transmission manual I've seen.

I pulled the pan and strained the oil. There were a couple of black plastic bits that look like part of a bushing. I'm going through the manual now to see where it might have come from. It's not complete so there may be some more bits in there.

Have you ever had to play detective and identify parts in your pan?? (I remember someone on the forum doing this--you perhaps?)

The oil was a little dark but not too bad. There were some very fine small thin shiny metalic flakes in the bottom of the pan. Perhaps part of the brake band lining? Not sure... Still optimistic that I can find a cheap fix. The filter was ugly.

Thanks again for the PDF--it's a winner for tranny problems!

Hal

[5by5]

http://s496.photobucket.com/albums/r...t=DSCN0837.jpg
http://s496.photobucket.com/albums/r...t=DSCN0838.jpg
Here they are. Black plastic about 5/8" long. Only two pieces which seem related but don't really fit together.

Do these look familiar to anyone. I've inspected the linkages around the selection piston but nothing looks obviously broken or missing.

I cross-checked against the 722 manual pdf from Dinesh but nothing jumps out.

Hal

[dineshh]

Hal,

I have taken the valve block out and the intermediate plate recently. But, can't recognize what the black plastic bit is. There was a white plastic bit like that on the top side of the intermediate plate which is a clip on.My advise is to slowly pull down the valve block and take off the intermediate plate. Once the plate is off, you will get a better look at the innards. You will need a new gasket when you replace the plate. There are bunch of pieces like that in the valve block too. This was my first glimpse in to an Auto tranny let alone a Mercedes one.
To keep the area clean, I bought a roll of freezer paper and laid a piece down on the floor under the tranny and another on the workbench. Once it is off, use cling film to wrap the valve block.
Don't forget to identify/mark the individual bolts as they are different lengths.
As for playing detective, you probably have seen my post when I found the b2 Reaction valve's thrust pin on the bottom of the pan and the local dealership Forman gave me a puzzled look as to how it got there.

[5by5]

Dinesh:

Thanks for checking out the pictures. It looks like I get to dig in a little deeper. On question, do I have to pull the valve body to remove the intermediate plate?

Is the clip on the top of the intermediate plate open to the sump? It makes me wonder how some of this stuff finds it's way down

One problem--if the part is gone how do I know where it went? Maybe there will be some fragments left--otherwise I guess I need to find a trashed core at the junkyard and take it apart.

Anyway, thanks for the advice and encouragement.

Hal

[5by5]

Double post removed

[dineshh]

To remove the intermediate plate, you have to take the valve body out first and then the filter mounting. The intermediate plate runs the length of the sump. Ones you take it out you will see a square hole where the plastic bit goes. Otherwise, it is full of little holes with a plate mounted to it holding the gasket. When mounting the new gasket, you will have to use the mounting bolts as holding /aligning pins before tightening the plate holding the gasket. With our cars, everything should go back nice and easy. Otherwise, you will have to realign the intermediate plate.