'94 c280 transmission question
 

Does this transmission use vacuum control to shift smoothly? If so where can I find the unit and test it? I am asking because it shifts hard most of the time and the auxillary vacuum pump cycles for a while after start up. Just wondering if they are related. I do not hear any hissing noise to be able to find where vacuum leak could be. Thanks.

Yes, the transmission uses a vacuum modulator. The vacuum line connects to the intake with a rubber hose. IF that hose is disconnected, the trans will shift harsh.

or the hose could be cracked or have a hole in it... might need to be inspected

Thank you M.B.DOC!!:thumbsup: I checked the black vacuum line and found it disconnected. When I tried to hook it back up the rubber connector disentegrated. It took awhile to work a new piece on to the modulator body, BUT man she shifts pretty smooth now!! On to the next...........!