Been through the entire vacumn/electrical system that has to do with headlights and wipers.
Everything works fine except now, when I shut the car off after about 15-20 seconds, the wiper door pops up.
As near as I can figure, it is the (img. 1) wiper safety switch, which seems to bleed air after testing taking about 15-20 seconds. Which then I hear a click from the (img. 2) Headlight/Wiper Vacuum Actuator Relay Valve and then the door pops up.
Is the wiper safety switch suppose to hold vacumn at all times? I've tested two of these and both leak down...or should I be looking elsewhere?

(img. 1)


(img. 2)

 

The problem is that on the electric solenoid under your tachometer does not have the small cube piece of foam on the end of the bleed port to SLOW DOWN the bleed off.

The vacuum is bleeding off so quickly...that the actuator relay can change position and cause the wiper door to open.

By the way...if you look at the vacuum schematic...the drawing will show that square foam filter on the end of the solenoid.

Something so small that DOES make a BIG difference.

DUB

 

Thanks, never noticed any foam underneath.
Only tested the solenoid to see if it's working fine, it is...
a pic of the foam piece perhaps

Ok, looked at pics of the solenoid, and yes a small piece of foam...I'm on it.
Hope that is the ticket...gracias

 

Well the foam part sounded good
So I am back to...finding a safety switch yhay holds vacumn
Been through two of them now, Wilcox?

 

You might also try blowing compressed air through that metal 'crossover' [vacuum] tube which runs across the firewall, under the wiper motor. That tube has a dip in it which can collect 'crud' over the years; and, if it gets closed down, the vacuum system can have problems.

Remove the hoses from both sides of that tube and blow pressurized air through it to make sure it's clear. Then, reconnect the hoses.

The vacuum solenoid/switch on the tach and the 'park' safety switch that you mentioned can also have effects on the system, if the internal seals are leaky. Also, verify that the check valve in the vacuum supply line is good.

The foam piece on the end of the tach valve is there to filter the air entering that valve when it is exhausting. It has nothing to do with slowing down exhaust speed. If it needed that, it would have an orifice in that fitting.

 

Gentlemen,

The biggest issue with wiper door problems as most know is the safety switch located under the passenger wiper arm. The repop's available today are not a very good solution. They are very cheaply made and suffer from a design issue which I will not go into now. People try to give good advice based on wrong information from the manufacturer, and it gets passed on down from there.

The best way I have found to test the switch is two fold. A Mityvac is the best tool to use. Simply hook up to the middle port, and pump it down. It should hold vacuum. Next, push the plunger down halfway and support it in that position in a vise or clamp. This is the position it would be in the car with the wipers parked and wiper door closed. Leaving the Mityvac on the middle port, block off the lower port, and pump it down. It should hold vacuum till you unplug the lower port, then release it.

What causes wiper doors to open after shutoff is the imbalance between the control and actuating vacuums present when the safety switch leaks internally.

There is a solution coming soon for this problem. I've been working on a rebuilding kit for these valves that will be available soon, along with a video series on vacuum problems for our cars.

Scratch, If you would like, I could send you one of my rebuilt valves to "field test". Let me know if you're interested.

 

I have had air through everything including the solenoid and everything electric
Every system seems to work as it should other than the safety switch, and when tested, they both will not hold vacumn.
My old corroded one worked better than the two replacements I've tried so far.
Dave, I will PM you on your project

 

Dave J,
Great explanation and when and if you get these vacuum switch made....let me know...via a PM. I would like to "test drive" a few and see how they do.

And not knowing if you know and you more than likely do know this ...but the same switch is used for the hot water shut off valve. The problem is that no one makes it with the correct tension spring so when you slide your lever over...you are not fighting against the tension of the spring...which is stout for the wiper arm...obviously. So if you make some with the light tension spring...that would also be a good marketing strategy. I have to remove the springs and replace them with the correct ones so the HOT-COLD lever does not spring back when it is engaging the vacuum switch as designed.

I have checked these vacuum switches (like you described) and from what I have found that causes the wiper door to come up is the missing piece of foam.

DUB

 

When I bought my car, all the vacuum accessories were intact and operational to a certain extent.....but the vacuum storage tank under the left fender, stuck to the well liner, was shaped like a gas tank, and sure enough the steel had leaks, so I tossed it, and just spliced the lines, and guess what?? tons of strange operational crap went away.....engine running headlights up/down easy...wiper door normal....

but over the years, the headlights are now fixed position, and the wiper door is now electric, with intermittent wipers......

 

The vacuum system is not designed to bleed off and should hold vacuum. My 72 will hold it for about 2 days when left to sit. I'd take David J.s offer and try his valve...

David J is on to one major issue we've fought for the past few years and you’ll notice I do not have that part on our website. (And David, I’d be interested in those kits too).

At one time there was a reproduction valve that worked. (It was imported)
For some reason they changed the internal plunger inside the valve. I talked with the manufacturer about a month ago and told him we had a video on how to test the valves. His response was that "another vendor did a video of this" and his valves passed his test so they were right…. WRONG! The other vendor used the wrong nipple to test with.

You don’t test the valve from the lower nipple you test it from the vacuum nipple which is the middle one. It is possible for the valve to hold vacuum on the lower nipple but leak when pumped up from the middle one. (At least with the reproduction valves it is). So if you get a repro valve, always test it from the middle nipple.

The check valve at the engine is another part that will let the vacuum drain out. Make sure the check valve is holding vacuum, and really any combination of parts in the system could be causing this same issue.

69-72 Wiper Arm Vacuum Relay testing.

 

Tested from the middle nipple, would bleed down. Tested the check valve also...I actually didn't test my original corroded one, it may actually still work
DavidJ is going to send me one of his...gonna test it out

Thanks for all the input

 

I agree 100%. The vacuum storage should hold....in regards to the storage tank/reservoir.

But you would be so kind to explain to me why when I installed the cube piece of foam on the electric solenoid for the wiper door...the issue of the wiper door coming up after the car was shut off stopped immediately.

I completely understand the physics of the system...and I know that some of these aftermarket parts are NOT ALL THAT...in some cases.

DUB

 

Dub-

I have no idea why putting a foam block on it stopped your door from coming up. There really is no logical reason unless possibly your solenoid was leaking down through the intake and somehow you blocked it with the foam or maybe the glue used to hold it place. It really isn't the norm that's for sure.

I've had stranger things that that happen. Believe me, I know you are top shelf when it comes to experience with these cars, this was just an oddity.... lets call it a Vacuum anomaly

BTW.. I have 10 of the arm valves heading our way on Weds. I'll test all 10 and get back with you all.



Willcox

 

Scratch,

You new safety valve was shipped out today. You should receive it Thursday. I tested it on my car, and it performs flawlessly. Let me know how it works..........

DUB,

I sent you a PM on my valves. Additionally, I have been trying to figure out how you cured the "winking wiper door" issue with your vent filter. As you know, the vent is sealed off with the door closed, it shouldn't bleed off. There's lots of anomalies with these cars, and I know you know what you're doing.

Mr Willcox,

I will be in contact with you very soon

Also Wednesday morn I will be out of town on my annual Walleye fishing adventure through this Sunday. I leave the madness of the city for the wilds of the sandhills of Western Nebraska.

 

Dave, just received the wiper arm safety valve Looks like a stock setup.
May not be important, but will it require a dust cover boot over the plunger spring?

 

Thanks!!!

I also know YOU also are TOP SHELF also...and a great asset to the Forum and Corvette repair industry.

I know that the foam fixed it because I could remove it and the wiper door would come up after the car was shut off....and when it was put back on...it stopped. GO FIGURE!!! More than likely was the solenoid...but saving the time and headache in servicing that solenoid...I figured I would let it ride.

I would have one due to allowing dust/dirt/water into the moving portion of the switch.

DUB

 

Installed Dave's part works as it should. One happy ****

Do you mean you have one or I should get one?
And I still have not found a piece of foam yet on the Solenoid...but will

 

Years ago, we had these made.... We have a limited stock... and when we run out, I doubt we'll make more.



http://willcoxcorvette.com/product_i...ducts_id=28188

 

Ten valves received and tested. Ten valves failed.... All valves hold vacuum on the lower port but leak from the middle port.

In the door vacuum system.... as far as operation:

When the wipers are turned on the tach solenoid blocks vacuum to this relay, the lack of vacuum at the relay will cause the door to open. When the door opens the limit switch is pushed and the motor runs. So while running the middle port is not blocking vacuum, the lower port is… but there will not be any vacuum there because of the tach solenoid is already blocking it.

When you turn off the wipers, the solenoid opens allowing vacuum to this switch, the arm comes down push the plunger which now ports the vacuum to the relay. The relay gets vacuum and will close.

So what's this mean...

It means the valves will work and function as designed while in operation. However, (The OP has found out the hard way) when in the closed position the vacuum will leak off the system from the middle port. (They are leaking out the top under the cap, not the top nipple) If the large hose side is in proper working order, the door will rise. The only way to stop this would be to place a one way check valve between the valve and the top of the relay.

You can test the relay for this issue by applying vacuum to the middle port and covering the lower one with your finger, the relay should hold vacuum this way.

If the large hose is not in good shape and leaking vacuum, the door will probably stay shut and the defect goes un-noticed. This is why few are complaining now about the newest run of valves..

 

[QUOTE=Scratch;1586901960
Do you mean you have one or I should get one? [/QUOTE]

You need to get one.

DUB