Off and on my 190d looses vac to the interior = no shutdown or vent / heater control (defaults to hot). Trans shifts normally, brake booster functioning normally. I have the vac diagram for my car on cd, never can find the leak! Put a gauge on the vac pump, pulls a good vac. I have been tracking this down forever. I have changed all the rubber connections I can find, disconnected the heater from the circuit, removed all of the egr from the vac circuit, pinched off lines here and there. For a while, I had the heater disconnected and that at least let the car shutdown eventually. Had it all working for a while and today - boiling in my car in traffic and when I finally got home, no shutdown, in the rain.

What is the best method to find this problem once and for all?

anyone ever fitted a vacuum pump from a ford powerstroke (works heater and 4x4) or a saab (works cruise control) ??? I would just run the interior off it.

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1982 300sd, new project car to restore

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