Hi all,

I bought my 87 back in September. It shifted kinda hard from 2 to 3, but both the PO and his mechanic thought it was a vacuum issue. It wasn't too bad in any case and I figured it could be adjusted.

The shifting has gotten worse and sometimes now it makes a clunking noise when shifting, especially at low RPMs. On a really cold day, it doesn't seem to want to shift at all unless I floor it.

I took the car to an indy mechanic that a couple other Mercedes diesel owners I know use. He seems knowledgeablea and forthright. He diagnosed and fixed a suspension issue for me that the dealer couldn't figure out, so I think he knows his stuff.

He told me that it's not a vacuum issue. He said there was a slight leak in the transmission and that there might be some damage inside from lack of lubrication if the PO had not kept the transmission serviced. He said he could open it up, he's not sure what he'll find.

Does that sound right to the gurus here?

I know I can get a Mighty Vac to check for myself, but I'm not car-handy. If anyone has some detailed instructions on how to check vacuum (preferrably with pictures) maybe I can double-check for myself what's going on before I start thinking about lots of $$$ for transmission repair.

Thanks for any help

Tim

If you are not planning on doing the work yourself, a good machanic with a great concern for your car is priceless. How did he seem? Does he care more for the car or his bottom line? When you find that person, you have no other option that to trust them till they prove you wrong.

When I bought my first MB, I met just such a mechanic. He was working on several other MB the seller had. He gave me his # and has been more help than I could ever imagine.I can call him from anywhere in the country to ask questions(and have).THANKS PETE .I will trust his judgment till he proves me wrong.

__________________
81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

On top of the value cover there is a black square box. Inside there are switch for the trans, replace them all....
I had a clunking noise on my 81 300 TD when shifting from time to time ..... which lasted for a long time until I saw my driver's side rear wheel sloping outwards .... It turned out to be a bent trailing arm .... and had the sub-frame mount changed on that side also.... trans shifts like new now ....

A test on the condition of a trans is have stick in "N", and move to "D". The trans should shift into gear within three seconds. Then "N" and go to "R" and should be the same... Another suggestion is to change the trans fluid and filter and see how the shifting is. clogged filter or/and old dirty fluid will cause a shifting problem.....

bill
p.s. dealer do not generally have old mechanics with knowledge about older MB. this guy sound alright, but on a job like this, MB dealers are my choice cuz of the guarantee... had quotes from 5 MB dealers on my trans, low of $3,500 to $7,000 in US. Canada price $2,500.00

bill

When I do this, it takes about 3 seconds to move into D. Going into R is worse. When it does shift into R, it shifts hard and clunks slightly. No clunking going into D.

My mechanic changed the trans fluid and filter hoping that it would improve but that did not change anything.

Symptoms are classic lack of vacuum to the modulator.

The 87 TD has a vacuum line to a device on the driver side of the IP. From there another vacuum line goes to a switchover valve and to a vacuum amplifier (blue saucer looking thing). From the blue saucer there's a line to the transmission modulator. So basically there's a hundred and one places that can leak.

If you don't have a vacuum gauge and have to be shown how to use one, your best bet is to see if any vacuum lines are loose, broken or not attached. It's common to knock the line to the transmission loose while replacing the oil filter. Check that there's no transmission fluid in the line that goes to the transmission. If all that checks out, get a second opinion from another reputable MB independent shop.

Sixto
93 300SD 3.0

If you earn about 120.00 per hour take your car to mechanics. To pay 60-80 per hour out thats what you have to earn. If not like most of us learn to get involved. The more you do the easier it gets as well. Self confidence grows right along with your efforts. It is one thing you really cannot purchase in this world. We all had to start somewhere.
You have a tremendous advantage with the existance of this excellent site. In my time auto repair was almost a self learnt thing totally. A mity vac is a very small price to pay in the overall cost of what you might be facing. It even has residual value as you can later sell it on ebay later if you want.
You can also prevail and find out if the mechanic knew what he was talking about. Opinions are just opinions in general without verification. He may have been right but why roll the dice? I almost bet he did not check the vacuum out before giving his opinion.
Roll the dice too many times in life is like scratching in pool games. You just plain loose. Your mechanic may still land up with the job as doing internal things to an automatic transmission is for the really experienced few. By testing the external systems yourself at least you will be sure it really needs it. It's all in the archives. Or ask questions as you get started. Many on site members have a lot if not vast experience in this area. I also believe you can do it or would not suggest it. The clues were in your post. I also know you were already thinking along this path. So I thought to boost the ideal up a notch or two for you and verbalise the rational for it might help you as well. Or at least try to explain somewhat how I view these things.

I would love to learn this stuff. My problem is having zero knowledge to start with. I've never worked on cars, never even changed my own oil. Looking at the schematics isn't too helpful when you don't know how the things should look in an engine bay.

What I would really love is either someone who could spend an hour pointing out the basics of what is what so at least I know what I'm looking at. Failing that, even a couple pictures of an engine bay with little pointer thingies. I've found some pictorial documentation on DieselGiant but it's generally closeups of things. I don't know where to start looking for the things in the close up.

I've been shy about asking mechanics to spend their time teaching since I figure that's a sure-fire way for them to lose business. I know there are mechanics on this list. How would you feel about teaching your customers how to do some of the basic stuff?

Tim

Here's my hypothesis. It's shifting worse now because you're using your heater and there is a vacuum leak somewhere in the climate control system. Try turning off your heating system and see if shifting improves. I'm not familiar with the 87 climate control but I'm guessing it's the far right button on the climate control. It's the simplest vacuum test that requires no guage or mechanical savvy. Report back the results.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'm going on a long drive tonight. I'll try with and without the heating system.

So I drove around the block a couple times. With the climate control off, it shifts quicker and quieter into R from N. No difference I could feel shifting from 2 to 3.

Thanks
Tim

You will not need or have to understand schematics to do it. Some of the guys have it all commited to memory and will make various suggestions of what to do as you go along.
They will describe exact locations accuratly and how to evalute your readings with the mity vac or it's equivelent. No previous experience becomes experience this way in conjunction with what you read. Plus of course the helpful hints. It really does work.
You just finished testing the climate control for leaks. The mity vac is just more positive and perhaps more accurate. It has less room for interpretation errors for example.
You indicated the reverse engagement time was less in your quick test. That may have been because there is a vacuum leak or the transmission oil is at a lower temperature from the very short trip. More likely is the senario you have also other vacuum leaks that mask a clear cut answer. If it did or did not hold actual vaccum was not exactly clear. Using the mity vac is just far more conclusive.
You are going on a longer trip this evening. Do the same test again when the transmission is warm. You might just get a marginal improvement for example like before. That would indicate it is one source of leakage but perhaps not all of them. It takes the vacuum pump/gauge to check running and static vacuum pressures. There is no real other substitute I can think of. Again it is doable by you.
It has been mentioned before by some members that these cars should have come with a mity vac type tester from the factory. There is just so much vacuum stuff aboard. The low cost harbour freight model should get you by for intermittent use . By that I mean owners that are self servicing their cars. About twenty five dollars in canada on sale where things usually cost more. Take notice that with Kerry Edwards thoughts and guidance you have already partially identified potentially one vaccum leak already.

Anything new come from this?

I found this thread because of a loud clunk I have in my transmission when accelerating with the engine warm. No clunk when cold. No clunk when you floor it and run up to 50+ mph like the car was stolen. (This problem may have been here for a while. I tend to drive it like it was stolen all of the time. I just noticed it in some traffic a few months ago...)

Ideas?

In the mean time, I'll keep searching...

-Jim

__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.