Hi there everyone,

I've got a 1993 w124 300d 2.5 turbo that has been in the family since new. It has always ran running flawlessly and has only 150 K. Hear a pic of my engine bay.



However, more recently shifting has become a bit rough and would only shift well above 3500 rpm.

I saw on another forum a guy who had a similar issue and i followed his method and bypassed the automatic transmission vacuum modelator and connected directly to the vacuum line (as shown in this link W124 Diesel 4spd Auto Rough Jerky Changes - Mercedes-Benz Owners' Forums).

Shifting became a whole lot smother on the day that i did the bypass however, as time passed the roughh shifting came back but in a less intense manner and when i floor the pedal i even get some wheel spin. Should i follow the advice seen in that link and take apart the vacuum modulator for a clean?

On to the second problem and more major problem. With a cold engine, the car has no brakes, or better yet, the brake pedal is really hard and i really need to work my quads muscles to get the car to stop in the drive way. The engine also doesn't shut off. After some minutes of warming up, i gradually get my brake assist back and the car can shut off.

From what i've been reading it all points to a vacuum leak...however, where to start? I hooked up my hand vacuum pump gauge and started testing stuff based on these two diagrams:





The vacuum lines that come to the mushroom/flying saucer thigy located near the air filter, that is marked as Y31/1 that control the wastegate and egr valve mechanisms do not hold vacuum at all. They don't even try to. When testing these canisters, the vacuum side looses air directly to the "Out" side and "atm" side on the part. Is this normal?

When measuring vacuum at the 4 way connector right off the vacuum pump, i get around 20 inHm, however if i plug the pipe that goes to the mushroom thingys i get 25 inHm...does this mean they are bad?

On the 4 way connector, the tube that goes inside the cabin holds vacuum perfectly, however the other tube that is that goes to the automatic transmission vacuum modulator (now bypassed by me) and has that green little filter/surge pot does't hold vacuum and loses it relatively fast. Should it hold vacuum?

Would really appreciate some help as i'm kinda lost. Thanks