Transmission Suckage. 1987 300D turbo, om603
 

87 300D turbo, om603, slushbox, too many damn miles, etc, etc.

Since I've had it (5 months) the trans has always been, well, less than perfect.

Bought it knowing there was a leak at the pan gasket. Drove fine, has to be topped off every once in a while. Lately though it's not so much with the driving fine. The lag between shifting into a gear and the thunk that tells me it's actually putting power to the wheels has gotten longer.

Today it started doing a new trick, when accelerating it kinda sucks up to about 3k rpm then the tach stays put while the car accelerates up to the shift point.

I'm going to rip into the thing and do the gasket thats been sitting on my desk for ages, is there anything else preventative or adjustment wise I can do? If this was my jeep I'd be doing solenoids and band adjustment but I can't make heads or tails of these things, it's like somebody used engineering when designing the sucker!

I would fix the leak, but before going much further I would do some searches using the search feature on Bowden cable adjustments and vacuum modulator adjustments. I have the same transmission and when I first got the car it shifted terribly. I thought it was done for...but the vacuum modulator and the bowden cable were both way out of adjustment. The general consensus seems to be...check for any and all vacuum leaks with a mityvac and and fix those first so that you have a baseline to start from. After that minor adjustments to each one in one way or the other worked for me. There are some more scientific means of adjusting but you will just have to look for one of the many threads on it. You will find some threads that tell you how to check the modulator on the transmission to make sure it is holding the specified vacuum as well.

From all of the varied threads on this topic it seems like it should be adjusted for firm shifts but you don't want it to bang into gears too hard. You don't want to adjust it where it slides into gears (what yours may be doing) or you barely feel the shifts as this will wear out the transmission way too fast. I've got almost 300,000 miles on mine and there is no indication of needing a rebuild anytime soon.

Oh also check out this thread if some minor adjustments and troubleshooting don't get you anywhere...you may need a spring kit depending on the symptopms: http://www.peachparts.com/shopforum/diesel-discussion/237763-my-superior-shift-kit-thread-w124-300dt.html

I'm sure some more knowledgeable experts on this forum will jump in at some point and offer you some other pointers after you give us a bit more information from your basic troubleshooting.

Mercedes transmission hate - just hate - really hate - not having the correct amount of fluid in them.

Fix the leak - replace filter - risk the cost of new transmission fluid (drain torque converter as well!) => Dexron III (I think for your transmission - check in the book)

Good info! I've got 343k on the car and AFAIK original all around for engine and trans.

Bowden cable is adjusted, I hadn't heard of the vacuum modulator so I'll look into it. I know the car got all new vacuum lines and pump right before I bought it.

How hard is it to drain the torque converter?

There's a little hex bolt in the torque converter, remove it and the converter should drain the fluid .

My auto that was in my 300td flared badly and 50% of the time it started of in 2nd gear. When I pulled it from the car I noted that the fluid was a dark grey/purple with a crap ton of metallic flake in it. Needless to say my wagon now has a stick.

There's a little hex bolt in the torque converter, remove it and the converter should drain the fluid .

My auto that was in my 300td flared badly and 50% of the time it started of in 2nd gear. When I pulled it from the car I noted that the fluid was a dark grey/purple with a crap ton of metallic flake in it. Needless to say my wagon now has a stick.

There is all sorts of voodoo about adjusting the modulator. Sometimes it works, sometimes it doesn't.

Transmission flares between 2-3 can indicate a problem with the K1 spring, 3-4 with the K2 spring.

It gets complicated after that. The right way to diagnose an automatic transmission is to measure the pressures. Low working pressure could indicate a worn out clutch pack or a valve body defect, which may well explain your problem.

Replace the gasket, change the fluid, and hope for the best. You have a lot of miles on that box.

Those benz transmissions suck when they start going out.

I have a good 722.303 for the regular 84-earlier 300d. pick up only in N texas. greyhound wont ship 150 lbs anymore.

replace the gasket, fluid and put in at least the K1 kit, but better yet the 722.3 superior shift kit (Superior Transmission - Superior K722A-D).

The K1 and new M1 fluid made my transmission quite crisp and pleasant (it used to flare like crazy 2-3)

Cheers!

Shift kit ordered wholesale. I'll drop the pan this weekend and clean up the gasket and do fluid. Then when it gets here I'll do fluid again to really clean it out.

Are the gaskets reusable? It looks like it should be, but I'm never sure.

I replaced mine when I did my service -- beware of the filter kits with the wrong gaskets (especially the wix). I had to drive to the dealer for the correct part. Were I you, I'd just drain the fluid right now (pan and TC) and then drop the pan when the kit comes, replace the fluid again, replace the filter and gasket.

I've got a gasket from here. Need to grab the filter, probably stealership for that.

You may be able to grab it at a local parts house as well. It's usually sold with the wrong gasket.

I've got the pan dropped. Old gasket was about as brittle as my sisters holiday attempts at baking.

No major shavings in the fluid. Everything looked pretty good. New gasket is on the cleaned up pan and I've got a new filter coming in tomorrow. I'm gonna button it up and fill things up then take it down to my family mechanic (who hasn't seen the car yet). Gonna have him put it on the lift and talk through things.

Judging by the undercarriage I have a leak somewhere that is getting to the rear out put flange and being flung all over the undercarriage.