o.k. if you are ready for this, here we go:

My car is a wonderful Mercedes1983 240D automatic Gold/Palomino Leather(132k). i'm very proud of it. It is pretty straigh...and strong.
AT first, my car experienced high rpm shifting from 2-3 and 3-4.

I went to my mechanics and he returned me my car with a slipping shifting (at full throttle) from 2-3 and 3-4 with almost no horse power and it shifted too soon 2-3 and 3-4.

I went to a second mechanic then he changed a broken switchover Valve, changed the transmission oil and filter and went to a road test. Same thing. He was not able to adjust the transmission modulator.

i bought a Mytivac, park the car on the street in full sun(It's still cold here in Montreal) and did the pressure test and here are the numbers:
(this is the vacuum diagram: http://home.comcast.net/~phantoms/va..._240d_auto.jpg )
1-Vacuum from the pump: 25``
2-Vacuum before the green Surge damper: 17.5``
3-Vacuum after the green Surge damper: 17``
4-Vacuum at the exit of the vacuum control valve (at idle): 0
yes... 0

Now my question is: do i take the vacuum correctly?
if i well understand, there is a line(with the green Surge damper) bringing vacuum at the top of the vacuum control switch then going out by the side of the valve(near the adjustment bolt) going to the switchover valve then to the transmission. I did plug the mityvac near the adjustment bolt. Am i right?
So can i fix the valve??? If i try to adjust it (with the bolt) what are the effect i mean if i turn clockwise?
On the other hand, should i change it?

After that, i disconnect the vacuum line going down to the modulator, and went to a road test to see what change it makes.. Nothing change.
The problem is that the less vacuum (or zero in my case) to the modulator on the transmission, the harder the shifts would be, and I should have no slipping.
So there is another problem here. TheDon toll me about the K2 to fix my 3-4 slipping problem, what about the K1 for the 2-3 problem?

Thanks again...
KarL

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KarL
1983 240D automatic Gold/Palomino Leather(132k)
1980 240D 4speed Manuel Black/Palomino Leather(RIP)

Your link doesn't work. Have you tried pulling vacuum on the trans modulator directly? If it doesn't hold vac then you need a new one.

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i did, sorry, my mechanic did it and said that it was holding pressure with no leak...
Is there an another way for the modulator to be broken ??
but i got no vacuum going out the vacuum control valve(in the ip) so how can adjust it to let the vacuum go through ?

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KarL
1983 240D automatic Gold/Palomino Leather(132k)
1980 240D 4speed Manuel Black/Palomino Leather(RIP)

There is some good info here about adjusting it and checking to see if it is working properly. Try searching for something like "adjusting the vacuum control valve" and see what comes up. I checking mine awhile back so I know the info is here.

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I read almost everything about it but nothing clearly talk about cleaning or adjusting the VCV when nothing is going through...

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KarL
1983 240D automatic Gold/Palomino Leather(132k)
1980 240D 4speed Manuel Black/Palomino Leather(RIP)

Here's what I did with mine:

I took mine off the car, and opened the front "plate".
Under that plate, you can see a coil spring that presses up against a plunger that deals with the vacuum line on top.
I cranked up the tension with a pair of plyers with one hand, and tightened the nut with a wrench with the other hand.
That really cut down the range of vacuum from (I'm guessing) around 0 - 5.
It shifted harsh, clunked into first, the whole bit.

I then loosened up the nut again, and the spring wound out a little. That opened up the range of vacuum, and the eliminated clunking downshift.

So, what does this mean to you? Probably nothing. You might need to get a new one. You can get one for approx. $50 every now and then on Ebay.

I would still take it off the car and see if I couldn't fix any obvious problems with it, though.