New 300SD owner - where to get parts? And trans problem.
 

I just bought a 1981 300SD from the original owner. Only 150k miles, but needs a few things (windows, cruise, etc.). Where is the best place to get small used parts like window switches, climate control buttons, etc..

Also, I've searched the web and learned alot about tranmission problems, but my 240 was a manual and I haven't dug into the auto yet.

The problem is harsh shifts. I know what causes it, but I'm not sure where to start so that I don't have to go over and repeat myself.

The 1-2 shift is pretty harsh unless I'm on the throttle. That would seem to indicate that the vacuum is not enough at low speeds, correct? Sometimes in traffic, I can be in 2nd for a while and it won't shift until I give it just a bit more throttle. Then, it's very abrupt even though I'm only at 1200 rpm. High throttle shifts are smooth and firm, but part throttle is NOT.

I've replace one vacuum switch (located in the black box on the valve cover) since one was backordered, and there was no change. Do these switches have any affect on the transmission other than if they have leaking hoses?

I've adjusted the transmission cable to force higher rpm shifts (it was rapidly shifting through to 4th and still does a little sometimes). Maybe I should back that off until the harshness is corrected?

What a fabulous car. Coming from a "I think I can, I think I can" 240D, this car is powerful and luxurious.

Thanks in advance for any suggestions. This forum is great!

Buy parts from Fastlane, which can be found at the top of the page. Purchases there help support this site, where you get technical help for free. If you don't find the part you're looking for, call the number and ask. Fastlane actually has multiple sources for parts but only one of them is listed on the web.

As for the transmission, read Steve Brotherton's article here.

You mention you are looking for USED parts maybe if you tell us in what area of the country you live someone can guide you.

I've purchased a lot of used parts from this place: http://www.mercedesdismantlers.com/prod.html. They have reasonable prices and will work with you cherry picking a part.

Congrats Tenknots, on becoming an owner!

I have had my 84 300SD for three months and I love it. I've got about the same transmission issues that you do and I am still in the process of replacing vacuum tubes and flaky rubber connectors.

I'll be watching this post for answers myself, just to see if I get some inspiration, which happens all the time around here!

300SD transmission
 

When I first got my car almost two years ago with 174,000 miles on it, it had problems like you report with your transmission. One of the first things I did was to take it to a local MB dealer that has a shop with a good reputation, and have them look the car over to create a list of things it needed. I also asked them to see what they could do with the tranny's hard shifting.

$220 later I had a punch list and a MUCH smoother shifting tranny. I've since worked my way down the list with parts from e-Bay and OEM parts through my local, non MB but excellent, fleet oriented diesel mechanic. Maybe not as much fun as fixing stuff yourself, but I wanted to get it running as a reliable car. And, I had been told by a number of people that "the diesels always shift that way", which I knew not to be true based on riding in lot of German taxis, most of which were diesels.

Maybe that would work for you.

OK, here's what I found over the weekend.

I bought a Mityvac (cute little sucker) and followed the instructions that were posted elsewhere.

Vacuum off the "t" to the brake booster was 20, but rose slow. Vacuum to the trans modulator was 0!

Plugged the line going to the EGR at the "t"and got my vacuum to the trans. Watched the little mityvac show the vacuum decrease as I gave throttle, so I know the valve is working. Plugged the line that goes to the EGR at the "t" (I've read about plugging the EGR and was considering it anyway) and drove it - much better. Still firm, but no jerks. It seems the EGR spaghetti on top of the valve cover had a leak somewhere. I had replaced the fingers before, with no improvement.

By the way, I got 23.5 mpg of maybe 3/4 highway driving. Had the air on most of the time, but didn't drive real fast. Seems low, is it?

Had the fun job of replacing 2 window regulator guides. Someone should come up with a way to screw them into the regulator rather than having to peen it.

As for the used parts, I'm near DC.

This is a great resource!

Then you're near Potomac German Auto.

On a semi-related note, what's a good place near D.C. to get a 300xD serviced?

(sorry for the hijack)