On my '85 300SD, you have the transmission vacuum control valve on top of the IP (I call it the CL valve = controlled leak valve) right? OK, so it's vent line goes up to the firewall to this solenoid/valve-thing. What is this solenoid for and why isn't it turning on? I have by-passed it and the tranny is now shifting like it should. I have heard that the solenoid is controlled by a temperature sensor and that sensor must have gone bad. My Benz Buddy says he knows where it is and how to replace, so that's no big deal. But my biggest question is what is this silly solenoid for and what are the other 2 vacuum lines going in/out of it? I do know that when it doesn't work, I get mushy shifts and way too much flaring between gears, and it gets worse as the car warms up.


Thanks all!

Does this help at all?

http://home.comcast.net/~phantoms/vacuum/egr_california.jpg

Yeah, somewhat. So when the solenoid valve turns on at 50 degree coolant temperature, it switches from full-up vacuum off the pump (through an orifice) to controlled vacuum (also through an orifice)? Wonder why that is....maybe I don't care. I just need to bug the wiring and see if it's the temp sensor that's faulty or if it's wiring.


On a separate, yet related note, my ignition does not turn off when the cab is warm, only when it's cold (10 degree F or so). Think I may have a cracked rubber connection piece at the ignition switch. How hard is it to get to the vacuum switch connections under the dash on my W126?

Travis