91 300d 2.5 tranny prob
 

Hi everyone, new to the forum. also new to Mercedes diesels so kind of a newb so please be patient if you could:). Just bought a 91 300d from a neigbhor up the street with some transmission issues and trying to see if its just the vacuum problems some seem to have or if i just need to replace the tranny.

the car itself runs great and everything works. i picked it up for cheap because the transmission dosent upshift all that well but downshifts fine if you get into the throttle. I have read that this usually has to do with vacuum and is not very complected to fix. My main question and what makes me think it needs a transmission is when it is in overdrive or 4th gear? when it goes from 3rd shifting manually from 3rd to drive, it does not engauge in gear. it will keep speed, but if i push on the throttle the engine will rev the car just wont accelerate until it downshifts. I do not know if this is controlled by vacuum or electronic i assume it just needs the transmission replaced.

all help is appreciated i just dont want to replace it and have the same issue it does right now. thanks in advance for any suggestions.

Dan

In general the fist place to start if you have not done it is to change the Filter and the Fluid.
It is a long read:Transmission Vacuum and adjustments
Mercedes-Benz Transmission, Steve Brotherton, ImportCar, February 2002

great thanks for the artical:). My neighbor said he already changed the fluid and filter but i will get in there and take another look. i was thinking i would just rebuild it for peice of mind.

I have a friend who is a master tech at mercedes and thought i would have him rebuild and adjust the tranny. the car is very clean and everything works so putting money in the car is worth it to me, i am going to have him take a look at it and see what he thinks. I would do it myself but not being dodge, chevy or jeep i am frankly lost, these cars are just so different:(.
I plan to learn more about it over time and work on it myself but i am moving about an hour away from work and just dont want to drive my jeep everyday since it currently gets about 12mpg because i built it to drive mostly off the paven path.

dan

thanks for the info on the valve body springs.

I went ahead and had my friend rebuild the transmission and adjust my vacuum system after i replaced all the lines. the car runs great now and is awesome to drive. Im very happy with my little benz.

I have one other thing i need to figure out. the head rest do not go down when i push the switch. It all works i just have a leak i still need to find. followed the vacuum line all the way back to the engine bay and it works till that point i think i have a couple small leaks to track down and it should be all good.

While i was at it i also added some newer 16" c class wheels to the car to improve the looks.