My 1991 300D used to shut off almost instantly. Now When I turn the key to off, it takes a few seconds. Not a big deal, but I just wanted to see if there was anything that could be adjusted.

No adjustment you can do,you must have vacuum leak in system,check all vacuum hoses,lines,connectors,an other possible is shut off valve at top of diesel injection pump,have to check with vacuum gauge.

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MB STARS Master Guild Technician,12 years MB tech
6 years independent shop owner

Thanks!

I am going to replace the vacuum shut off swith on top of the pump, they are very inexpensive and with 165+k miles, I figure it can not hurt.