w123 transmission problems
 

I just wanted to run this by the experts before I took any further steps. I recently purchased a 1982 300TD with about 200K miles.
There was no record for recent transmission service. The transmission was not shifting out of second and slipping badly. I adjusted the t-handle on the vacuum modulator (two turns clockwise) and now it seems to shift OK. I also drained the pan and replaced the filter (couldn't get at the torque convertor drain bolt). The fluild was dark and smelled burned. Obviously the car had been driven for some time with the transmission slipping. Also the filter had a large quantity of carbon like flakes in it but there was no evidince of any metal in it or in the pan. I intend to flush it and drop pan at least once more. Is it likely that I will need a new transmission soon?
Were the carbon flakes I found from the clutch linings. What kind of service could I expect form a rebuilt transmission?
Thanks for your help.

Most of the transmission techs tell the story that with good service an automatic transmission will wear out at between 150 & 200k. MB auto transmissions are no worse, and not really any better than that. Yours sounds like maybe it has had a minimal level of service so far.
That being said, sometimes one comes through that just runs forever. My 78 300D has the original transmission with over 350k, and it does not slip and shifts fine. But then, the 300D without a turbo has no power and thus the transmission is not worked very hard.:D

Torque Converter Drain
 

Marlene, my '83 300TD, has 226,000 miles and is really slow to engage reverse but shifts upwards solidly and exhibits no sign of slipping.

She slipped, flared badly and blew moderate throttle shifts when I bought her but some tinkering with the Bowden cable and fixing vacuum issues corrected all but the slow to reverse problem.

Maybe you can extend the life of your trans by performing the adjustments here: http://www.wagoneers.com/DieselBenz/Trans-ADJUSTMENT.html. I used this procedure but was able to achieve good shifting without having to go into the hydraulic portion of the procedure.

I also think you really should go after that fluid in the converter to eliminate what sounds like some seriously toasted trans fluid.

To access the torque converter drain, rotate the engine the correct direction at the harmonic balancer with a 27mm socket/ratchet until the coverter drain is accessible through the opening in the bottom of the transmission housing.



R Leo

Take enough fluid out to put 2 cans of Transx into it and drive a couple of hundred miles...
The symptoms you mention can also be caused simply by varnish build up in the tiny holes which control the hydraulic activation of the clutches for changing gears...
Since yours has been abused you might want to try this twice, changing the filter in between also.... well worth the cost of trying this....

Seeing lots of friction material in the pan is not a healthy sign.

Ussually, you can judge the life of these by how many seconds it takes the reverse to engage. Longer means more wear.

I'd do another transmisson fluid change. The torque converter drain plug should be 5mm. Rotate the engine until it is down. You can disconnect the driverside hose going to the trans cooler .. and drain it as well( anothe 1/2 pint).

Other thing is the vacuum must be correct. Make sure your pump is working correctly, all the lines are connected. Commonly, worn-out switches on the valve cover or someone breaks the tee-fitting on the brakebooster line(big 1/2 diameter black plastic hard line).

If this doesn't help- start saving your pennys. Quality rebuilt transmission(ie all plates, bands, seals,etc..) give similar life to originals. Factory runs about $1800 wholesale and aftermarket boys are $1200-1500. IF you live in a big city, it's easier to find a MB transmission specalist.

Michael