Hallelujah! Shift problems fixed!
 

Well, my transmission shifting issues are fixed. I finally gave up and took the 1982 300sd to the dealer. They warranty their repairs for a full year - parts too. A week ago the mechanic replaced the two valves on the valve cover. Friday after degreasing the engine, the car started revving up before each shift. Dealer confirmed that the vac valve the independent mechanic put on was defective and leaking. Several people here have said these have no effect except on the EGR. The dealer says otherwise. If valve on valve cover leaks, it sends incorrect pressure to the modulator and modulator will never adjust correctly until valve is replaced. My cleaning the engine had nothing to do with the part failure.

My 3/2 valve is blown. I tried to buy one at the local MB pick a part and they wouldn't sell me just the valve, they wanted to sell me the entire package for $150! ! !

I'll just pick up a new one one of these days soon....take about 30 minutes to replace and away we go!

If you don't mind me asking, how much did you pay? I'm almost at that step with my car, I can't figure this out for the life of me.

He gives pricing here: http://www.peachparts.com/shopforum/showthread.php?t=110901&highlight=vacuum+valve

but check out Fastlane for the parts......

Check for 3/2 valve

Here, if it works is a link to the part in Fastlane:

Link to fastlane

http://img.eautopartscatalog.com/live/D301312188MTC.JPG

As far as what I've said previously on this, the valves on the EGR are there to control EGR. They don't exist on vehicles without EGR. If they leak, they affect transmission shifting. If they don't leak, they don't affect transmission shifting. If they are bypassed or removed, they are not affecting EGR and they are not affecting transmission shifting

what would be better
 

Plug the 2 plastic vacuum lines that lead up to the valve cover switch. Plug them independently, i.e., don't plug one into the other, just block them both. The transmission will behave as if there are no leaks in the EGR system affecting the shifting (because they're not connected)

This seems to be a sticking point of confusion for people.

1. There are several incarnations of these vac valves, single, double stacked, double flat, etc, etc. Depends on year.

2. I can tell you for sure on the double STACKED models, one is for EGR, one is for shift control. And by shift control, it shunts HIGH vacuum to the modulator at closed throttle for obvious reasons.

If they leak, it'll screw things up, as Will has found. If your patient and your tranny/bleed valve on the IP are in good shape, you CAN do away with them, but it's a *****. It lessens your margin of "error" in your vacuum curve, that fine line between feeling downshifts and too soft light throttle shifts. If you hook up a vac gauge to the line to the tranny modulator and just do open the throttle on a car with functioning valves, you'll see the vac dive from 17inches or so down to about 10 as I recall, WAY faster than the bleed valve will move it on it's own.

I will never EVER own another automatic MB.

Glad your up and running Will, now let's fix those oil cooler lines! :)

Does anyone know where these valves are located on the '85 300D, CA version? I don't think i've seen them on top of the cam cover.

Find the correct vacuum diagram for your car and the great mysteries of the universe will be revealed. The vacuum control systems for the transmissions in these cars are really quite simple. Do a little searching and reading.

1985 is a special case, it has an electronic controller.

Are you refering to the vacuum amplifier?(blue thing)
It's not electric, vacuum.