70 Wiper Door Pops Up On Start???

[Carr C.]

I have a '70 Corvette and the entire vacuum system has been restored.

The headlights work PERFECTLY and snap open and closed.

The wiper system works perfectly and snaps open and closed.

The only issue is that after the car sits for a while the wiper door will pop up and then go right back down when you start the car.

Nothing else is winking or doing anything strange. It's just the wiper door.

I have treid all the suggestions in the "Troubleshooting Guide", but I cannot find any particular part of the system that fails it's test.

Obvioulsy it's not getting the appropriate "signal" to keep the door shut until vacuum builds.

I would appreciate some suggestions, becuase I have worked on this over and over.

Thanks in advance!

[Dave S.]

Re: 70 Wiper Door Pops Up On Start???

I have a '70 Corvette and the entire vacuum system has been restored.

The headlights work PERFECTLY and snap open and closed.

The wiper system works perfectly and snaps open and closed.

The only issue is that after the car sits for a while the wiper door will pop up and then go right back down when you start the car.

Nothing else is winking or doing anything strange. It's just the wiper door.

I have treid all the suggestions in the "Troubleshooting Guide", but I cannot find any particular part of the system that fails it's test.

Obvioulsy it's not getting the appropriate "signal" to keep the door shut until vacuum builds.

I would appreciate some suggestions, becuase I have worked on this over and over.

Thanks in advance!

Carr,
I had a similiar problem with my 71. I used Dr. Rebuilds troubleshooting booklet and traced it to the valve at the right side wiper arm. When the wipers are in the "rest" position the right arm depresses this plastic valve. In my case the wiper door went up/down at the time the engine was shut off. I do not recall the name of the valve from memory but there is only one.
The Dr. Rebuild catalog is quite detailed and helpful.

[Paul O.]

Re: 70 Wiper Door Pops Up On Start???

Carr

From what you described your control side of the wiper door system small hoses is losing/leaking vacuum before the vacuum is lost on the motor side large hoses. As Dave stated the wiper arm park valve could be your problem but it could be in other areas of the control side. Here is a list of possible areas.

1. Any of the small hoses on the wiper door side and connections
2. Wiper override switch ride side under the steering column.
3. Wiper door control solenoid behind the tachometer.
4. The control relay in the right wheel well.

Hope this helps it is best to use a vacuum compressor for troubleshooting as running the car make to much noise to find the leak area.

Paul 18046

[William L.]

Re: 70 Wiper Door Pops Up On Start???

Carr
I just went through this on a friends 69. If you have no leeks in the system, I'll bet its the vacuum control valve. Like Dave said its the one close to the right side wiper arm.
No sense in using a repo because they are JUNK we tried 2 of them with no luck. One did not work at all the other lasted about 10 cycles.
We pulled an original one off of his other 69's and it has worked ever since. If you need one I would do my best to find a original.
Bill