Hi all.

My '78 240D loses vacuum when doors are locked...surprise surprise. My question is this. It seems to hold vacuum longer the warmer the engine compartment is (after a long drive) and if it's humid/rainy outside. Is it safe to say that my problem more than likely is in the engine compartment??? And if so, what's the culprit?

Thanks to all!!!

If I remember correctly there are 2 small check valves that "Tee" off the vacuum line near the power brake booster. These fail and will leak vacuum off. When they get bad enough the engine won't shut down. One is for the door locks and the other on the A/C vacuum actuators. If you disconnect them one at a time and try to lock or unlock the doors you will determine which is for the door locks. I would try replacing it first. HTH

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