I need help with the transmission in my 1979 300CD. I noticed a few days ago, that it seems to start out in first and feels like something is binding. Tonight I was driving it, and it seems like it is getting worse. I have also noticed that it is taking longer than normal for it to engage into gear, or it seems like it is not engaging all the way. One last thing, the transmission was rebuilt about 20,000 miles ago, so I hoping that it is not going out. Any help would be great, and thanks in advance.

It sounds possibly like the vacuum modulator isn't getting enough vacuum. One common cause for this is a plugged port in the brake booster vacuum line, which is where the vacuum for the sub-system on this car originate (well, actually originates with the vacuum pump, of course, but the lines come off the brake booster line). The inside of the orifices can plug with built up soot or baked on oil after many years of use. You can try gently cleaning out the port with a toothpick or some other type object, but try to not increase the size of the orifices, they diameter of the orifices are critical. The proper repair is to replace the booster line, not all that expensive.
Or the line to the modulator may have come off for some reason, the modulator may have failed internally, uh, that's about all I can come up with now, there are other reasons this may have happen, but to have it happen suddenly like this, I think it's one of these items I've mentioned.
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I have a 1978 123 with lots of miles. It has been shifting into gear when I start, all the time staying in park. A few shifts through reverse and forward will clear it, and when it is driven a few feet all of that stops. Oh, and when I back it up cold it shifts into park and locks up. Have to be carefull.
Do you think this is caused by the same vacuum problems addressed here?

Today, I cleaned off all the dirt and grease that has built up around the tranmission pan, and checked many of the vacuum lines, and they all seem to be connected, but I have not checked any of them for leaks yet. Would it be a good idea for me to change the filter and fluid now, or should I wait until I can get a chance to get it into to a shop to have it looked at. I was also wondering if I might have a bad kickdown switch, since it seems to be starting out in first gear.

Eric

Today I changed the transmisson fluid, filter, and added some conditioner. Doing this seems to have made it shift better, but when I put it into gear or start off from a complete stop it seems to still slip or something like that. It also sort of makes a clunking noise when it is slipping and when I come to a complete stop the transmission seems to make a whinning noise.

I finally got the car into the shop, and they say that it is the tourque coverter, they say that it should be $700 to replace it. Does this sound resonable for this repair? They are also said they can't get to it until the end of the month.

I don't know the answer to the question of the price of the torque convertor, but if your car is like my 77 300d it should be starting out in 2nd gear. It should only go down to first if you depress the accelerator enough to activate the kickdown switch or you manually put the shift lever in L before you put it in D or put it in L and leave it there.

I was just at the transmission shop, and there is more bad news with the car. When the tourque converter broke, some of the pieces got into the pump, and wore it out. The shop says that they are trying to find a used pump, but are having no luck. I was wondering if anyone would know of a good wrecking yard that might have a pump?

You can buy a rebuilt transmission for about $900 so why spend almost as much on a transmission with 200,000 miles on it that might break again at any time?

The transmission should stay in 2nd gear at a stop but jump into 1st gear as soon as you touch the throttle. It is made this way to lessen the creep.

P E H

The transmisson is in good shape still, and the shop said it can rebuild the one i have for $1100, if it needed it, which it doesn't. They said rebuilt ones are $3000 installed. They said that it was starting out in first because the pump was broken, and not building up enough preasure to shift properly.

I read you post wrong wrong, thoiught it said 200,000 miles since transmission was rebuilt. So I would go with fixing what you have.

They might tell you a rebuilt costs $3000 bit I know you can put in a rebuilt for about $1200 including rebuilt torque converter and new vacuum valve because I did it.

P E H

A local(Pasadena, Ca.) shop quoted me about $2800 to install a factory rebuilt tranny. I should have gone that route.
Instead, I paid $1200 to a friend-of-a-friend to have mine rebuilt. Picked up the car a day before my wedding. Drove it on the honeymoon, transmission died 600 miles from home. Then paid another $1200 (never recovered first $1200) to have a rebuilt unit shipped to stranded car and several hundred more to have it installed. This one lasted four months. Drove it to place I bought it, they installed another, which lasted about two months. They installed another over a year ago which to this day does not function properly.
I'd be real curious to know how your tranny is running PEH. Seems my $1200 specials have cost me plenty.

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1995 C280
1999 Triumph Daytona 955I - my speed fix.
1982 300TD - Gone, but not forgotten.

Today, I went back to the shop and see how they are doing on the search for a used pump, and they said that they have found a few, but they are worn out. I found out that a new pump is $750, and the shop said that a used one runs about $75-$100. I think I am going to go without my car until they can find a used pump.

Dave,

How is my rebuilt transmission working? One simple word: PERFECT. And it is 4 years and about 40,000 miles later.

I bought it from a rebuild shop in NJ that only rebuilds MB and BMW automatic transmissions. They only rebuild them, don't install them. I R&R the transmission myself. I had R&R a transmission in a Chevy 4WD not long before and after that, the MB R&R was a breeze.

The shift characteristics of the rebuilt transmission are much different, all to the better. It was almost worth the price for to get the improved shift patterns. The owner told me they always put in the latest level MB rebuild parts.

Sorry you had so many problems. I would probably feel the same way you do if I had same problems.

I questioned local transmission shops and they acted like they really didn't want to rebuild a MB automatic and wanted around $2500. Dealer wanted over $3000 just for the transmission, no labor included.

If I ever need another auto trans, I would do the same thing: get it from a shop that specilaizes in rebuilding MB auto transmissions.

P E H

I made sure to take my car to a shop that knows what they are doing. They have done several Mercedes, as for they had a 420 SEL in the shop today when I was there. They want to keep my car in the shop, taking up space to save me several hundred dollars, instead of doing the easy thing and putting the $750 new pump and getting my car out of the shop as fast as they can so they can work on the next car in line. That is what I call good customer service.