1978 450 SL Central Locking - Works sometimes, others not

[AstroturfHead]

Hi, as the subject says, I own a 1978 450SL. When the car is running and I'm inside, if I press the lock closed it will close the passenger door. However, when I stop the car and get out and use my key, it doesn't automatically close the passenger.

It did, however, work correctly before I put the radiator in, a full week ago. I put a new radiator in the car and now it does not work correctly.

I just tested it again. When the car is on, the locks work perfect. When I stop the car, only if I immeditaly press the lock does it lock the other side. If I get out of the car, it will not lock the other side. I know these are vacuum regulated, and my breaks still hold vacuum after 2 or 3 hours after I turn off the car. Can somebody help me? Thank you.

 

[Malcolm Brown]

In the pre-85 models I believe there's a vacuum 'reserve' chamber under the wing (driver's side?). A leak in this would give the symptoms you describe.

 

[Mikesmerc]

You may have disconnected vacuum tubes around the engine bay, perhaps the vacuum control to the adjustable headlights or that its one of the vacuum units to the doors,boot or petrol cap has a perished rubber seal.
I am referring to the 123 series with my answers to this problem. Have a 72 Sl but no C.L.
Regards
Mike