Remove the under dash cover panel on the left side , slide the driver's seat all the way back and jamb your face up under the dashboard (I know) , look at the back of the ignition switch ~ there are two brown plastic pipes leading to it, connected by short bits of soft & rubbery vacuum hose ~ this hose *MUST* be firm and take a twist to remove . 90 + % of the time they're oily and soft, ready to fall off in your hand .
Go to M-B Dealer or European Partshaus and buy one meter (minimum) of the correct vacuum hose and replace those two short bits then pop the hood and look at the back of the injection pump until you find those same brown plastic pipes and replace the rubber vacuum hose bits there too .
Now , carefully begin pulling at the other plastic pipes and rubber connecting hose bits,
ANY that you can pull off without twisting are BAD AND LEAKING so replace them one by one ~ never disconnect more than one rubber hose bit at a time ! .
There's a goodly chance you'll need two or more Meters (3' lengths) of rubber hose but it's $pendy so be aware before you buy it .
I always buy at least TWO METERS (6') before even looking because they're always more bad hose bits than one can imagine .
I *think* the hose size is 3.5MM but not positive .
If you cheap out and use Pep Boys, O'Reilly's Kragen, Shuck's etc. vacuum hose be aware it'll go bad in about 12 months, I don't like doing crappy repairs but you might be forced to .
-Nate
wmscawaz wrote :
My 1982 300D runs rough at idle and does not turn off by turning the key. When the key is in the off position, the engine runs smoothly. Please prioritize ideas on checking the vacuum system.