1976 300D Locking system vacume leak -How to Use them?? - Mercedes-Benz Forum

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post #1 of 2 (permalink) Old 05-18-2010, 08:25 PM Thread Starter
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1976 300D Locking system vacume leak -How to Use them??

Yes the usual ever elusive vacuum leak...
could anyone tell me what the common things to fail are on these cars? or where to start looking for the leak?
could it be the little valve that opens and closes on the drivers door or something
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post #2 of 2 (permalink) Old 05-19-2010, 11:26 AM
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Go buy a mitivac tool first of all. The kind that lets you pump and read vacuum. Get a vacuum diagram of your car. If it's the same as W123, yellow w/ red stripe is the locking circuit, yellow with green stripe is the unlocking circuit. If it's like a W123 you can test at the junctions under the carpet rather than test the things in the door.

In my 123 wagon I ended up replacing the tailgate actuator and two door actuators. Note that they can leak in on direction only -- holds vacuum for locking but not unlocking for instance so you need to test both.

Currently: 1967 250 SL, 1963 220Sb, 1965 300SE Lang, 1971 280SE parts car, 1972 Alfa GTV, 1965 Alfa Duetto, 1993 BMW R100R
Past: 1971 250 C, 1985 300 TD, 1967 250 S, 1968 280 S,1981 300 D, 1982 280CE, 3 Facel Vegas, Borgward Isabella Coupe, Alfa 2600 Sprint, Volvo P1900 (yes), numerous less interesting Volvos, ...
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