PeachParts Mercedes-Benz Forum - View Single Post - Vacuum to transmission-1980 300 SD

864Lightning · #2 12-19-2006, 10:02 PM

I have a 79 300 SD and I found the Peterschmidt diagram to be fairly accurate. I bought the car a few weeks ago and am still in the learning process.
My trans would flare between shifts, engine kinda reving between shifts.
I disconnected the vac line to the trans modulator and this resulted in head snapping shifts. Nothing like my Lightning truck but fairly harsh.

Just last night following the MercedesShop writeups, I calibrated my vacuum control valve to have 9 inches at idle going to the trans. It was 22 inches before hand. I havent had a chance to test it yet..

As for the PeterS diagram. I have a large dedicated line from the pump to the brake booster, then a smaller line from the pump to the first rubber Y . A line from the first Y then goes down to the VCV on the injector pump. The Y on the VCV has a orifice in one leg, that leg has a white plastic ring around it.. The other two legs are free flowing, one going to the VCV and the other going to the transmission. Another line hooks to the side of the VCV and this is the atmospheric vent line from the cabin..

This doesnt answer your question much, but just wanted to add my observations.. This is a fun car to learn to work on.. A nice change from my computer controled cars..