Another question about wiper door issue

[Stephen B.]

I have a 72 coupe and I have to ask why my wiper opens and stays open every time I start the car. There are no leaks that I can find or hear. After I turn the engine off the wiper door will slowly close......Help

[Russ S.]

Re: Another question about wiper door issue

Check the positioning of the door over ride switch below the steering column.

[Patrick H.]

Re: Another question about wiper door issue

There are no leaks that I can find or hear. Help

There are leaks, but usually too small to hear.

Buy the vacuum system testing guides from Doc Rebuild and MidAmerica. They describe how to test each component and determine what isn't working.

The simple one is to test the silver valve that connects via filter to the intake. I've had a couple fail - no noise, but poor system function.

[Edward D.]

Re: Another question about wiper door issue

Wiper door opening means either the vacuum control system is venting (not holding vacuum) when it shouldn't or the control valve is bad. Wiper door opens when control vacuum is vented causing spring in control valve to push down dogbone valve directing engine vacuum to the pull open side of actuator. Besides the lines, leaks are common at the manual override valve under the steering column, the switch operated solenoid behind the right side of the dash, the control valve diaphragm, and the interlock valve under the wiper door on the passenger side. Using a mityvac or similar and plugs for lines test the components (including hoses) individually throughout the system. Getting the troubleshooting guide is a good idea. So, test until you find problem component and replace it.

[Stephen B.]

Re: Another question about wiper door issue

Thanks to all for the reply

[Bob W.]

Re: Another question about wiper door issue

Patrick, I have the Dr Rebuild guide do I need to buy the Mid America also ?

Thanks Bob

[Patrick H.]

Re: Another question about wiper door issue

Patrick, I have the Dr Rebuild guide do I need to buy the Mid America also ?

Thanks Bob

Probably not. Using that you should be able to figure out what part(s) are not functioning well.

[Bob W.]

Re: Another question about wiper door issue

Patrick,
Thank you for the reply

Bob

[Edward D.]

Re: Another question about wiper door issue

Stephen,
There are a couple really simple things you should check first in troubleshooting. Are the vacuum lines connected properly? I have seen lines from the control valve to actuator reversed resulting in the problem you have. The bottom port on the valve (open) goes to the port on the actuator can on the same side as the actuating rod (firewall side). The top port on the valve (close) goes to the other side of the can towards the front. The middle port goes to engine vacuum. When the car is running, pull small hose from top of control valve and check for vacuum with a finger. If vacuum was not present, commence going back thru the control system until you find where it is venting. If vacuum present, shut off car and check that the control valve will hold a vacuum pulled with a mityvac. If it doesn't, replace the control valve.

[Stephen B.]

Re: Another question about wiper door issue

Edward, thenks for the reply. Are we talking about the control valve under the rh wiper? Which is new, but hay, it would not be the first time.

[Edward D.]

Re: Another question about wiper door issue

Stephen,
No, the valve under the RH wiper is the interlock valve, it prevents the wiper door from closing (by venting the control vacuum) until the wiper arm is parked closing the valve. The wiper control valve is the larger item probably in the right fender well of a 72 I think (earlier years have it on the firewall). It has a big round flat vacuum can on the top with a small control vacuum line and 3 larger hoses underneath that go to the actuator can and vacuum source. Its exactly the same control valve as used for the headlights. Your headlight system uses two of these, your wiper door has one.