Hi everyone. First let me thank this forum for being so helpful this far. I've had my '84 300D turbo (first time W123 owner) for less than a week and have learned so much from this great resource.

I have searched the forums and websites long and hard but I can't seem to find a concrete solution (or solutions) to my tranny problem.

First of all, when I shift from Park to Reverse or Drive, there is a substantial delay and then a hard CLUNK when it does shift. And when I let off the gas while driving, I can hear something clunk in the drivetrain. Fairly loud. There is no vibration when accelerating though, so I don't think it's a flex disc or support bearing (I don't think.) Diff mount maybe?

It also clunks when it downshifts coming to a stop, and the shift from 3-4 at any throttle input is much softer than it should be, and flares occasionally. I know that the 2-3 flare is common and fixable with the K1 spring kit, but my question is, would that kit fix this problem as well? I haven't yet pulled vacuum on all vital components of the system but I am getting there. The vacuum line from the little green check valve to that plastic valve on the injection pump is shot. That green valve may very well be shot too. I looked at the vac. valve levers on top of the engine and they don't look too bad. I think they still have a little life left.

I am going to change the trans fluid and filter tomorrow but I might hold off if anyone thinks I should try the K1 upgrade. 1-2 and 2-3 are bang on, and very crisp at WOT, but 3-4 is the problem area.

I'm pretty sure there is a vacuum issue somewhere about the car. The door locks can be finicky and very very slow at times. Sometimes the RR door doesn't even lock when I lock them. I'm starting to think that little yellow check valve may be leaking too, it looks like its the original one haha.

Any help is much appreciated,
By the way these cars ROCK!

Patrick

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1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

^^^

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1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

a little more thoroughly... somewhat like mine below, and this will tell us the important mileage numbers your car, tranny etc. have on them.

Done. Thanks for the advice. I've done a little more looking at it seems this could be a B2 piston problem. Or is that just totally inaccurate.

The thing I am most worried about is the severe clunking when I let off the gas.

Patrick

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1984 300D Turbo W123, 198k - The Tank
1999 BMW 328i 5-sp - The Scalpel

Ours just had the drive shaft bearing and rear tranny mount done.
Before it was fixed, when it kicked down, the drive shaft popped into the floor boards. It wasnt so good. It was really loud and violent. It wasnt too bad under acceleration compared to how obvious in was dunring deceleration.

It drives ALOT more smoothly now. It is a little lumpy but I cant really tell- I haven't driven enough Mercedes 300D's to know if it was right, or or needed tweaking.

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1984 300D

i had a clunk when i would put my car in reverse and drive backwards. that was a bad rear axle. after replacing that, i had no more issues. just food for thought.

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

Patrick???..where'd you go??

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alimony

Hello everyone, thank you all for the wide range of good postings. I resently acquired a very expensive vehicle (1979 300D, 174,880 miles) for the bank breaking price of $175.00. The car's been sitting in a field for over 8 years, just one step to the junk yard until I stepped in. Well thanks to a fello diesel car driving friend and I, we got the engine started, that's all it took, now I'm hooked. Did some massive preventive maintenance, still have a few vacuum problems, especially when it's real cold outside. No reverse or able to shut off engine, except manually. I'm more concern about the transmission, I had it flushed out a week ago. It's always been sluggish, now no reverse. Anyone have any ideas how to isolate if it's a vacuum problem, (already have vacuum gun).

Tony

Tony,
Was the REVERSE not working before you flushed the transmission?
IMHO, your lack of a REVERSE has nothing to do with the vacuum system!
With your hand vacuum pump you can test your IP/Engine Shut-Down device that is located on the rear of the IP, between the IP and the oil filter. You should be able to very easily shut off the enigne by connecting the hand pump to the port on top of the IP's Shut-Down "Box" and pumping once or twice. IF you canNOT get the engine to shut down, then either someone installed the IP Shut-Down Box incorrectly or the diaphragm has ruptured. You will readily know if the diagphragm is leaking for you will find that you have been sucking engine oil out of the box's vacuum port! IF you end up replacing your Shut-Down Box, be sure you have the "hook" properly engaged inside the IP or you could cause a run-away incident and destroy your engine!
Report back with your findings BEFORE you try to replace the IP/Engine Shut-Down "Box".
Regards,