on my 85 300d,ive had intermittent not shutting off issues.it will be good for a while then not shut off.ive checked lines ,cannot find vac leak,put vacume to switch and it shuts down with a couple of pumps on vac pump.door locks are ok,im wondering why its good for a whole day ,then atnight it wont shut off.i probably need to recheck again.?if its got a leak at resoirvoir wouldnt door locks not work after several days?

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95 e320,87 sdl,79 300sd

You have to have a Vac leak somewhere, Commonly the line to the ignition, the rubber Joiners tend to suck air too. so it you have any rubber that looks powdery or cracked then I would replace them.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Minimum vacuum for shutdown is 13 inches....

Verify vacuum pump supply first..

Three times during the approx 8 yrs I've owned my TD, it has appeared to lose all vacuum except for brakes while driving. I can tell when it happens because the downshifts get hard. When it happens, turning the key off makes absolutely no different to the engine. Each time when I've driven the car subsequently, it has been back to normal. Don't know what is malfunctioning.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13