Transmission won't shift when it's cold
 

I have 81 240D. The transmission won't shift in cold weather until engine is up to temperature. I don't know if it's the modulator valve, or if it's vacuum or fluid related. Any help would be appreciated. Thanks very much.:confused:

Is the transmission fluid up to the proper level with the engine warm and idling? When was the transmission fluid/filter last changed? Will the car move at all? It moves but won't shift out of first or second or whatever gear it starts in? Or something else?

My 77 300D does something similar...I always assumed it was because of vacuum leaks... :\

Mine does the samething, I have to wait for it to warm up to about 60C before it will shift. It will go into drive and reverse fine but it will not shift into 3rd.

Fluid is up to proper level and was changed approx. 30K ago. Transmission will go into all gears properly, will shift from first to second, but it won't shift from second to third or third to fourth until it's warmed up.

Wilbur I think every W123 that I have ever had with an auto tranny has always shifted "differently" until they warmed up.
You should be OK if it shifts fine after everything warms up a bit.
Kind of like me trying to walk away from the bed in the mornings.....

I had this issue as well, and it was made ALOT better by a fluid change. I would do it again, especially if the car had gone a very long time with out a Tranny fluid change before the one you did 30k ago.

I remember Whunter saying something in the tech session about what exactly causes it, but I can't remember.

Like Jimmy said it's pretty normal for the transmissions to not shift properly when they are cold. A fluid and filter change might help a little. But in general you just have to drive it gently until the transmission gets warmed up. My wagon does the same thing.

Are you sure it won't shift at all, or just wont shift until very high rpm's?
Cold shift points are pushed upwards by the fact that the shift points are controlled by the location of the rack. Cold diesels have so little horsepower that you have to push the accelerator much further down than when the car is warm. This means that the transmission 'thinks' you want the fastest acceleration possible based on the location of the rack so pushes all the shift points upward.
Have you tried backing off the accelerator to induce the shift? In other words, get the engine rpm's just past the point where it would shift when warm, then back off the accelerator to get the transmission to think you don't want high rpm shifts, let the shift happen, and then push back down again.
Alternatively, I think it is probably possible to adjust the bowden cable or rods so that the warm shift points are low. I believe this would lower the shift points when cold also.

Where is the bowden cable located on a 77' 300D?

No cable on a 77. It has a series of rods going from the accelerator linkage on top of the valve cover down thru the intake manifold and back to the right side of the transmission.

what about the 1980 and 81 300Ds? i never saw a rod OR cable.

Someone here knows the exact years and can answer your question, but there were some years without either I think. Don't know what controlled shift points on those years.

The change to a cable was in 82 not sure about rods

Thanks guys you have been very helpful.