My 1972 wiper cowling opens itself but will not close. When I turn on the windshield wipers the cowling opens but will not retract itself. I have been told that the cowling opens by vacuum but retracts by electricity. I have replaced the accuator to no avail. It appears everything is connected but the cowling will not close any suggestions?
Submitted by: Jeff Groh
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The 1972 uses several items to operate the wiper door. The door is opened and closed by the vacuum actuator that you replaced. The system uses an electric solenoid controlled by the wiper switch. This solenoid opens and closes a vacuum source to a vacuum relay valve. My experience is that the relay valve is the problem. It's located at the rear of the right hand (passenger side) fender. It's the same type valve used to operate the headlight actuators. If it's original, it's probably leaking. You usually have to run the engine to generate vacuum and listen for leaks at the control valve. Sometimes it's difficult to hear over engine noise. I use a stethoscope and sometimes the engine noise is still too loud. In that case I use an air conditioning vacuum pump to power the vacuum system on the car without the engine running. You will be surprised at how many air leaks you will hear with the engine off. Check the relay valve for leaks and proper operation. Sometimes the valve is dirty and can be cleaned with Armorall. Don't use solvent - it will damage the plastic valve parts. It has rubber 'o' rings inside and the Armorall will rejuvenate these. If that doesn't work, replace the valve. You will also need to check the electric solenoid valve. It's located under the dash. I'd say use a vacuum gauge at the control valve and turn the wipers on and off and see if the vacuum signal goes away when the switch is off. There is a bypass valve under the dash that might be positioned incorrectly. The bypass valve will keep the wiper door open by design. There is one other item to check. It's the interlock valve operated by the wiper linkage. It won't allow the door to close when the wipers are running - that is not in the parked position.
This sounds complicated. However, once you troubleshoot the problem and fix it, it will be well worth the effort. Good luck!
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Jerry Rebman on
7/16/2010 11:52:40 AM
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