anybody have any pics on how to adjust the Throttle pressure cable & vacuum modulator. My 1983 mercedes 300SD isn't hard shifting but when it goes into the next gear it get louder and hesitates. It then shifts and quiets down.

"Flaring" is what happens when the transmission disengages from the engine during the shift. The engine runs up in rpm and a split second later the trans engages the next gear the engine returns back to a lower rpm.

Do you have "flaring"?

If so, which shifts are affected? Is it just the 2-3? Or is it both the 2-3 and the 3-4?

Thats what it sounds like "flaring" can you give me some tips please. Actually its three and four that are being affected.

The best thing to do for flaring is to reduce vacuum to the transmission.

Do you have a Mityvac that you can use?

What is a mityvac and how do I reduce vacuum?

A mityvac is a portable vaccum pump that allows you to provide vacuum to troubleshoot most functions on the vehicle. It's nearly mandatory for any work on these vehicles with extensive vacuum controls for the transmission, brakes, and door locks.

Once you get the Mityvac, we can go over the proper procedure to set vacuum to the trans.

I have a question, which may or may not pertain to the info in this thread? I have been looking at a 1987 190D, well havent seen anything besides pictures, but have corresponded with the owner several times a week for the past few weeks. He stated he had the transmission rebuilt about a year ago, but instead of letting the technician finish "tuning" the tranny, he took the car, as he was tired of renting one while that was in the shop, and he needed his car back. Here is a quote from what he told me about his transmission..."Work was done by AAMCO and I've got the receipts.
Only the rubber seals needed replacing, but, I needed a working car, and decided to get the transmission rebuilt. With 20/20 hind sight, time and
the car being home near it's local mechanic, I wouldn't have done it. No major motor work. It does use a bit more oil than it should. There's a leak
around the head gasket that I haven't bothered to repair. The vaccum modulator or vaccum to the transmission might be needing attention. I'm not
sure. It seems to shift late, but, that transmission can be 'tuned' so by so many variables, I haven't played with it. If I need a 'jack rabbit' start. (ok,
with a non-turbo diesel, a 'jack turtle' start), I simply downshift into '2' and then when it gets speed up, I pop it back into "D". Do you think making the adjustments you guys have been talking about in this thread, would help his problem?
thanks,
coadman

This is my vacuum control valve with the domed cover pryed off. I was unable to release the locknut. I was able to turn it with a 1/4 wrench a little to the right and the idle decreased. Took it for a test drive and noticed it helped the flares. Its not flaring where it used too. Then when I got home I took the key out of the ignition and it wouldn't shut off!! put the dome back on drove it around a little. Now its shutting off properly.

How do you release the locknut to adjust the screw properly? everytime I turned the locknut with the wrench the screw turned with it!!

Brian, is that brown line that goes up to the tee the one your referring too to check the vacuum?

The configuration is slightly different on that valve. But, the intent is the same.

Unfortunately, you ignored my procedure and started turning things without any gauge to determine the outcome. The valves are quite sensitive and you'll damage them if you adjust too far.

The T is right in the photo, directly above the VCV. You own the Mityvac and it's required to properly set the VCV.

Why did you not utilize it?

Furthermore, it's not possible for you to affect the idle when making such an adjustment. The engine should be shutoff during the procedure. That's the purpose of the Mityvac.

Your right. Sometimes I am impatient and cut corners. Something I need to work on. I will first test with the mityvac tomorrow before making any adjustments.. But like I said in the earlier post. How do properly remove the lock nut to adjust the screw?

Will the screw turn with the locknut attached? If so, then don't worry about the locknut. You'll see if it will have the desired effect when you pump up the Mityvac and turn the screw slightly.

The problem is that we don't know were you started from...........

Does anybody have a vacuum diagram? I can't check for vacuum because I dont even have a line on top of the vacuum control valve going to the transmission vacuum modulator. The previous owner messed up all the lines, and I have to rerout them.