1970 wiper door vacuum issue

[Mitch S.]

Happy New Year to all! Can anyone tell me what would cause my wiper door to slowly pop open once the engine is shut down? The complete vacuum system works as designed while engine is running, except as noted, about a minute or two after engine is turned off, the door rises.
Any suggestions for troubleshooting would greatly be appreciated, thanks in advance, Mitch

[Bill C.]

Re: 1970 wiper door vacuum issue

Mitch,

Do a seach on the TDB for previous posts..

Also - on the Corvette Forum there has been a really good thread going for somtime.
Here is the link- very helpfull.

http://forums.corvetteforum.com/c3-tech-performance/2361782-wiper-door-rises-then-closes-at-start-up.html

[Edward J.]

Re: 1970 wiper door vacuum issue

Mitch, a few things come to mind, the first is the metal check valve this check valve is made to hold vaccum in the reserve canister. the other problem is the vaccum switch that the pass side wiper rests on, theres a plastic and the button tends to break, sometimes you don't see the break,sometimes like my 72 the button was not even there to be found. when the switch button breaks the vaccum plunger will stay in that positon which it breaks and could be stuck between the the ports,causing a leak in vaccum out the vented port the extends through the cowl panel. let me know how you make out.

[Dave S.]

Re: 1970 wiper door vacuum issue

Happy New Year to all! Can anyone tell me what would cause my wiper door to slowly pop open once the engine is shut down? The complete vacuum system works as designed while engine is running, except as noted, about a minute or two after engine is turned off, the door rises.
Any suggestions for troubleshooting would greatly be appreciated, thanks in advance, Mitch

Mitch,
I had exactly the same symptoms on my 71. After reviewing Dr. Rebuild's troubleshooting guide I went directly to the vacuum switch on the right side wiper arm. That did the trick. The aftermarket vacuum switches you buy from any of the vendors most likely will have a "white" contact pad. (originals were black) I scuffed it up a bit and applied some "stove black" and it looks very good.

[Michael B.]

Re: 1970 wiper door vacuum issue

What is "Stove Black"?
Thanks, Mike

[Dave S.]

Re: 1970 wiper door vacuum issue

What is "Stove Black"?
Thanks, Mike

It's a paste that comes in a tube like toothpaste. It contains some sort of black dye that works wonders. Don't get it on your fingers. It will be there for a while.
Should be available in smaller hardware stores. It was made for use on wood stoves to dye the steel and keep it from rusting. I've had my tube for years and use it on and off to protect natural steel parts if a black finish is what I'm looking for.

[Edward J.]

Re: 1970 wiper door vacuum issue

Dave,
thats a great tip for the stove black on the nut and bolt finishs?

[Michael B.]

Re: 1970 wiper door vacuum issue

Dave,
Thank you. Have you ever used a product called Rub n Buff to simulate cad plating? It seems to work very well and when coated with satin clear last for quite a while on parts that are not heavily subjected to corrosion. The color looks very much like cad plating. Rub-n-Buff also comes in a tube, a small tube and is available at many Art Supply stores, I purchased mine at Michael's, a art supply store chain.
Mike

[Dave S.]

Re: 1970 wiper door vacuum issue

Dave,
Thank you. Have you ever used a product called Rub n Buff to simulate cad plating? It seems to work very well and when coated with satin clear last for quite a while on parts that are not heavily subjected to corrosion. The color looks very much like cad plating. Rub-n-Buff also comes in a tube, a small tube and is available at many Art Supply stores, I purchased mine at Michael's, a art supply store chain.
Mike

Thanks for the suggeation. I'll keep it in mind for my next profect.

[Terry M.]

Re: 1970 wiper door vacuum issue

That "Rub and Buff" (And this is a family site, right ) also comes in silver and will make a reasonable facsimile of zinc plate. It does, however, have a tendency to come off on fingers if not coated with satin clear. It will not pass real close scrutiny, but is close, inexpensive, and a DIY operation.

[Tom L.]

Re: 1970 wiper door vacuum issue

I'm curious about this Rub 'n buff. I just did a quick search and found that there are many colors.

Mike, What color was used to simulate the Cad plating?

And Terry, what color was used to simulate the zinc?

[Terry M.]

Re: 1970 wiper door vacuum issue

I'm curious about this Rub 'n buff. I just did a quick search and found that there are many colors.

Mike, What color was used to simulate the Cad plating?

And Terry, what color was used to simulate the zinc?

I didn't know there were many colors. I'll have to ask the perpetrator.

[Tom L.]

Re: 1970 wiper door vacuum issue

I didn't know there were many colors. I'll have to ask the perpetrator.

Perpertrator.... Now I feel bad!