240D trans
 

I am considering buying a 1982 MB 240D. the car is in good shape except the automatic transmission will slip in third gear when you are going up hill. It will shift into third for a few seconds and then junp down to second for a few seconds and then back to third. its like there is not enough pressure in the trans to keep it in third gear. the man who is selling it says he thinks this could be caused by a transmission vacuum problem? i have not owned a 240d yet so i don't know. what do you guys think?

Did the owner say this problem has just recently occurred with the car and before the transmission did not do this when going up hills? If this is a new problem then it could be the transmission is in need of some kind of servicing.

It may just be trying to downshift because the RPMs are not high enough to keep it in third. Does the transmission do this when driving on flat ground?

When going up the hill and the transmission downshift into second can you press down on the petal to keep it in second? Usually with an automatic transmission to get it to downshift you press the gas petal down and it should kick into a lower gear, causing the engine to run at a higher RPM until there is enough power to shift into a higher gear.

Also can you manually shift the car into second gear and have it stay in second gear?

Here is a site concerning adjusting the Vacuum on Transmissions:
http://www.continentalimports.com/ser_ic20242.html

Also there is a kick-down switch a described by the other poster and there could be a cable (bodwen cable) or lever that also needs adjustiment concerning the kick down.

If it seems like it is happening at a certain point when yo depress the Pedal it could be activating the Kick-down Switch dropping you to 3rd Gear and when you ease up on the pedal it goes back to 4th Gear.