mbeeman350

My 1972's wiper door opens and then shuts quickly when the engine is started! Headlight doors and wiper doors work fine when engine is running. Reserve tank holds enough vacuum for wipers and headlights to work after engine is shut off. Any suggestions? Thanks
Mark :steering:

rgregory

Check and see if you still have enough vacuum to open the wiper door or headlights before you start it. The actuator valve moves to the open position when there is no vacuum and takes a second to close which is just enough to open and shut the door. Mine started to do this and I know mine is no longer holding vacuum when the car is off.

72GACRZR

Check the check valve, the little one usually first from carb on vacumm line with 1 in and 2 out.

ddecart

That sounds like it's along the right lines. Your control side of the system isn't getting vacuum as fast as the actuation side.

How long does your car hold vacuum for after the engine is shut off? 1 minute? 1 hour? if it bleeds down, like Robert said, the relays move to the 'open' position. If there's a leak in the control side, it could allow the actuation side to depressurize first and makes the open/close thing happen.

bcliff

Mark,
My car did the same thing when I got it. It turned out the be the check valve that is located on the passenger's side of the wiper compartment, right near the wiper actuator. The valve with the plunger type end on it, the plunger on my valve was bad.

Tom