kansas123

When you test the wiper door safety switch, you hook up the mighty vac to the red port; mine does not hold vacuum so evidently mine is bad? Dr Rebuild says you check the switch hooking up to the white port; when I hook up to that port, it holds vacuum. does that mean the the internals are bad and so the switch is bad?

By the way, this is the switch on the pass. side near the wiper arm attach point; it has about 700 different names, who the hell knows which is correct.

Alan 71

Hi k,
How about the... Wiper Door 3 Port Interlock Switch?
My understanding is that the RED port is open REGARDLESS of the position of the plunger.
The WHITE port should maintain vacuum with the plunger in it's extended position.
Calling Dave J, Calling Dave J…….
Regards,
Alan

theandies

Wiper door vacuum safety switch.

It keeps the wiper door from closing when the wipers are not in the parked position by eliminating the vacuum to the vacuum relay.

It does the same job as the wiper motor safety switch but opposite. The wiper motor safety switch keeps the wipers from moving before the wiper door is fully open.

Dave J

Wiper arm safety valve is what I've always called it. There are about 3 different names for the same valve in the 69/70 GM service manual. Funny thing is the exact same valve is used in '77 - '79 cars on top of the heater box to control the heater core bypass valve.

The good Doc's video and method of testing the valve is WRONG. There I've said it. It shows the lower (white) vacuum port as the test port, when the red port is the one to test with the plunger in the extended position. There is NO vacuum present at the white port when in operation at this position. So, why does he test it there?

The proper test with the plunger extended is to connect at the red port. This is the port that has vacuum with the door up, and it should block the vacuum path there. The other test is with the plunger depressed. With either red or white port blocked, put the test to the other port and apply vacuum. It is designed to pass vacuum through it with no leaks. It should hold vacuum.

Here's how I test them........

kansas123

Hooray, thanks for the quick responses! Ordered new valve yesterday, although I sure wish that Delco / GM still made them. It seems that not very many of these knock-off ones work. Something sooooo simple, why can't they get it right. Oh well, hope I get lucky. Have a great day!

Alan 71

Hi k,
Did you realize that Dave makes a reproduction?
I believe Willcox (and perhaps others?) sell them?
Regards,
Alan

drwet

Where did you find one??? I just ordered one for my '79. (Same part is used on the '79 to control the hot water shutoff to the heater core.) I couldn't find one at any of the major suppliers. Finally ordered it from Willcox because they claim to supply them to everyone else, but they are backordered. By the way this one is to replace a cheap Chinese POS I installed about a year ago. Hoping the US made part is better.

kansas123

Ordered mine from Davies Corvette I am quite sure it is NOT made in USA; can't find one of those.............

Already shipped, be here Friday or Saturday

0Willcox Corvette

Most the imported valves have white caps. So you'll know when you get it, just check the cap. But test it before you install it.

The valves are back ordered right now, but from what I understand they are shipped and on the way to us now.

Willcox

drwet

The one that I have that failed prematurely was all black, but it only cost me about $25. It worked OK, but after a year it sticks. The replacements that are supposed to be US made (and better) run about $50-60.

kansas123

Thanks, you'll be hearing from me.....the one I received today did not test good, the red port did not hold vacuum. I had a feeling that was going to happen. Can you give me the part number for your part please? thanks

0Willcox Corvette

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

And ... just a FYI... the wiper relay and the heater core relay were actually not the same. They were close but the difference was the spring tension. The required tension on the wiper door relay and the heater control valve relay are so close that a compromise between the two could make them close. With GM the original relay was a bit stiff compared to that of the heater control 77-79 relay.

When dealing with the GM parts we could substitute the the heater relay for the wiper door relay but doing the opposite was not good. If you used an original wiper relay on a heater control valve the spring would be so stiff the control would move the temperature control lever.

The current reproduction will work for both because the spring on the valve is very balanced....

Willcox

kansas123

Do you know or suppose that the dust boot off my bad valve will fit on the one that I order from you? Might help keep it cleaner.... Thanks

0Willcox Corvette

I used to make the boot... I did it for years but my supplier went belly up about 5 years ago... To answer your question, yes the original boot will work with our valve. Is it needed???? Not really the valve will work perfectly without the boot.

Willcox

kansas123

I was looking at your website and found the diagram of all the vacuum hose connections for wipers and headlights on (my) '72, but could you tell me where the black hose from the wiper arm safety switch is suppose to go? On the diagram, it just sorta comes off the top position of the switch and makes a 90 deg and stops? Is it open to the atmosphere? On my car it goes to a port on my carb, which I was somewhat surprised to find. Thanks. The wipers and wiper door work perfectly thanks to the switch I bought from you.

0Willcox Corvette

The top nipple one the wiper arm valve is just a bleed off hose. It pass's through the firewall grommet and just ends there. The middle nipple is the source hose and the lower one is the one that goes to the vacuum relay small nipple.

Willcox

kansas123

So it shouldn't be hooked up to a port on the carburetor? I'll unhook it and see what happens

0Willcox Corvette

Here is a vacuum schematic of all the headlamp and wiper vacuum hoses.

bacevedo

Just to add to this discussion. Here we are 6 years later...There are several online video's that show how red port is supposed to hold the vacuum.

I ordered wiper switch (AKA Wiper Vacuum Switch on Firewall) for my 69 corvette from Central Corvette and neither the white port or red port would hold vacuum. They asked me to add a drop of light weight oil and retry it but is still failed to hold vacuum.

I ordered a second one from Keenparts (via Amazon) and it held vacuum on the white port but not the red port.

Does anyone know where to get the part that works???

Dave J

Willcox was the primary supplier to the industry and through their retail website. Unfortunately they are out of business due to the owners passing. I am the manufacturer and am supplying them now to both Corvette Central and Zip Products. Yes they are twice the price of the imported ones, but well worth the extra dough. They are essentially handmade and guaranteed for life. My return rate is less than 1%.

Corvette Central part # 453098
Zip part # WW-404

The proper way to test them is to connect a vacuum pump to the red port with the plunger extended, it should hold vacuum. With the plunger pressed down and the white port blocked the red port should hold vacuum with vacuum released when the white port is unblocked.