I have a 1982 380SL. It sits up alot and the last time I drove the car the door lock on the driver's side would lock but nothing else would( passenger's door, trunk. gas tank). Where would I start to find the problem?

There are others much more knowledgeable then I; but I'll start the ball rolling.

I suggest checking for a vacuum leak. If you can trace the vacuum lines back from the door, gas door & trunk you will hopefully find an easy to replace broken fitting.

you have to start by taking off the drivers side door pannel. that is where the control valve is for the system. that lock works manually. all the other vacume functions originate when that lock is used. The easiest way to check it out from that point is with a hand vacume pump that you may be able to borrow from some auto parts stores.

Dan

I was having similar problem. My mechanic did some testing and found the gas tank door vacuum ($99) was leaking. Also, check the two small vacuum filters at the Y-line connections under the hood. Best of luck.