mpopp2002

Looking for some help here - just replaced the wiper door actuator on my 1970 corvette. All is now functioning well... The door opens and closes with the wiper switch. (Happy the I diagnosed the problem!).

Here is my problem: After turning the wipers off again the door closes as expected but after I turn the car off - about 10 seconds later the wiper door pops up about half way.

Can anyone out there is corvette land help?

Mark

kansas123

Am no expert but it sounds like you may have a vacuum leak; the wiper arm safety switches are notorious for causing all kinds of problems. Has yours been replaced lately?

phil48315

When I restored my 1970 ...New hoses and switches.
The hoses didn't seal well on the safety switches under the dash.
I used a smoke machine to diagnose the vacuum leak.
A little silicone did the trick to get them to seal.

mpopp2002

Where do I find the wiper arm safety switches?

mpopp2002

I will give this a try... seems like a have checked everything else

Alan 71

Hi mp,
If the vacuum hoses have been in place for a long time (20 years?) you might consider trimming about a 1/3rd of inch off the ends of each hose.
This gives the hose a fresh diameter and surface with which to seal at each pipe it connects to.
A wiper door that opens on it's own is often the result of a problem with the 'control' part of the vacuum system, made up of the small hoses, the relay on the firewall, and the safety valve in the wiper bay under the right side wiper arm.
You can check their operation with a small vacuum pump (mity-vac, for example) that has a gauge on it.
You can also check the operation of the check valve. That's the gray metal fitting in the vacuum line that comes off the intake manifold to the rear of the carb. This valve helps maine vacuum in the systems when the engine is shut off.
Good Luck!
Regards,
Alan

kansas123

It's under the passenger side wiper arm near the post the arm mounts on. It's plastic and has 3 vacuum hoses hooked to it. If you have a vacuum gauge you can check the middle hose connection to see if it holds vacuum, it should and if so, that switch/valve is not the problem. You can also take the red and white hoses and hook them together; if your door goes down then, the switch/valve is okay.

phil48315

Saftey switch or override switches ?
My leak was at the override switches at the bottom of the dash under the steering wheel.
One is an override for the wiper door.
And the other is for the headlights.

0Willcox Corvette

The wiper system is supposed to hold vacuum... so if the door pops up, it could be the check valve at the engine but the most likely culprit is the wiper arm vacuum switch leaking vacuum down. Either way, your issue is on the small hose side and the system requires vacuum on the small hose side to hold the down plunger on the relay down... When the vacuum is released from the small hose side the plunger drops and the door opens because the large hose side still has vacuum.. Hope that makes sense...

https://willcoxcorvette.com/corvette...t-really-works

I have videos on my tech site to show you how to test the over-ride and the wiper arm safety switch. http://repairs.willcoxcorvette.com/?yt=1970&s=wiper

Willcox