https://www.corvetteactioncenter.com...print-697.html

 

Its sounds like you are on the right track. That actuator relay was bad on my system, You can unplug it and put your pump on the #10 hose and see if you hear air at the vent if so its bad. I jumped ahead and wrote a little break down to tesst your system but Im a couple of drinks into it before ai notice you may have it solvedand not realize it. getting the realy unscrewed and out to a point you can test it is the hardest part

First make sure the bypass switch under the dash has the both rods pushed in. These vent the switched side of the system.. In Wilcoxs ddiagram you can see the yellow hose (#6) controls both relays and is common to both sides. With the motor running see if you have vacuum to both actuators by unplugging the hose at the actuator and just putting a finger over it. If not thats one of your problems. Thnen make sure the (#7) hoses have vacuum. the number 7 hose also supplies both sides but you have to climb under the dash to check it. Check at the filter, then the check valve You could also seperate the sides here to see if one system works over the other. I've had a new headlight switch leaking that caused both sides to stop as well. if not the check valve or filter could be cracked. if you can determine that 6 and 7 have vacuum then you could jump to the relays and see if they have vacuum. While your under the dash you can check the override switches by pulling the #8 hose and then operating the headlight switch. if the switch is leaking, you will have no / minimal vacuum here.

#6 will always have vacuum with the car running, (#10 wipers and #1 headlights are the switched side). if both #6 have vacuum, then #5 and #3 should have vacuum. you can check the blue hoses too incase im *** backwrds, but you get the idea. Then disconnect the #10/#1 side and plug in your vacuum pump and operate the relay with it, it should pull the relay over and open the wiper dorr/ headlights by supplying vacuum to the #9 side/#4 sides. . if it doesnt work, try again unplugging one side of the #6 T (removing the headlights from the circuit)and see if the remaining wiper system will work. This should tell you if the operating systems are working. The other side is the switched system.
http://repairs.willcoxcorvette.com/w...or-testing.jpg




If your operating side is functioning, Then I would isolate the systems at the actuator relay in your passenger fender well down by the gills. Thats where mine was leaking the worst. Test that (#10/#1) with your pump and listen at the vent at the end by the blue hose #9 /#4 thats where mine was leaking. You can backtrack from here through the switched side of the system. If this sounds confusing its because im drinking to mourn my pup who passed today. she was almost 15

 

The way the relays work is #6 supplies the operating vacuum to pull the actuator rod towards the window or away. #10 is the switched side that pulls the relay rod inside to direct vacuum to either the #5 or #9 hoses. If the internal seals are leaking you can loose vacuum to both sides of the sytem as well as the headlights systems. to test itif you take the #6 and use a adapter you could plug it roght into #9 hose and see if the door oppens, it should. then do the vacuum pump on #10 and order a new relay. lubing and cleaning them isnt going to fix it. I tried

 

Thank you gentleman, I believe the info you've sent will be 'gold' for me. This has been a long time issue, it would be great to have it resolved. I've removed the dash and have access to the vac lines and related component. Had to replace the headlight switch, attached the vac pump to the carb side of the filter, that is when I found the 'leak' in the windshield actuator. My sympathies regarding the puppy, we lost ours years ago took 5 years before I could get another dog, they are truly 'member of the family'

 

This is great information. I will save it for use on my '68.

Can any of you tell me why my '72 opens and then closes the headlights and the wiper door when I start the engine?

 

how long can it sit before this happens, as in if you shut it off and go in a store or get gas, then start it a few minutes to 10 minutes later will it do it? sounds like you dont have stored vacuum to keep them closed, so its trying to fail open.

 

Every time I start the engine. The car is not currently on the road. All components are new and I have traced the hoses repeatedly.
Vac tank holds vacuum but you are saying I am losing vac somewhere while it sits. I don't understand why there should be vac to hold the doors closed as that is their normal state without vacuum in the system.

 

I KNOW what is causing this.

Look at this and you can pretty much figure out WHY this happens. Or at least I figured it out and know how to stop this.

https://www.corvetteforum.com/forums...t-problem.html

DUB

 

OK DUB I understand the problem as you explained it. What do I do? Buy new actuator relays? How do I know the replacements won't be like the old "new" ones?

 

That makes sense, sometimes mine does that, but not all the time

 

Come-on DUB let us know how to stop this. Do we buy new relays? Re configure the old ones? Who sells actuators that have the correct spring?

 

You can...if you wish...take apart the relay and swap out the spring. My method does not cause me for me to do this. And how I do it...is something I do not give away due to it is in the book I am working on. I cannot give away all of what I know here on the forum. If I did that then my customers could do a search on the internet and find it and fix it themselves.

BUT by me posting that thread...if a person has really good deductive reasoning skills..they can easily figure it out and what needs to happen to stop this. My method, you could never tell it was done by looking at it. That comment alone in itself is adding more information for a person to figure this out. And if they have hours in figuring this out and what to give it way...that is their choice. But they paid the price in their time and trying out countless things till they figured it out. Just like I did.

DUB

 

The spring in the new relays is too heavy. It takes less vacuum to activate the the actuator than the relay so the door opens and closes momentarily and if you wait after shutdown, the door will open and close after vacuum bleeds off. Mine takes a couple of hours to do that. I found two ways to solve it. You can either counteract the problem of the heavy spring by installing a spring in the back side of the actuator or you can use a controlled bleed in the vacuum line at the back of the actuator to slow actuation for a few seconds.

The easiest one is to use a small control bleed orifice like a 1 inch long piece of that red extension tube from a can of spray brake cleaner and insert it between the hose and fitting on the bottom rear of the actuator (fitting on the above pic) to make a controlled leak. It creates a slight vacuum leak but only when the wiper door is up and is nothing compared to the size of the carb inlet.
The other way is to counteract the spring pressure in the relay by installing a spring on the inside of the back of the actuator to counteract the high spring pressure of the relay. See above again. I used part of a light spring from a pop-up underground sprinkler and it seats on the inner metal rim of the actuator and the metal center plate of the diaphragm.
Both work but figuring out how much spring and everything else to use is a pain. A controlled leak using a free tube is easy and flat out works. There are 2 sized orifices commonly used on those red spray can extension tubes and you want the smallest orrifice possible like with brake cleaner. Slide a 1 inch piece into the vacuum line with a 1/4 inch sticking out then install the line on the actuator tube and that should cure it.

 

Well there is an answer to the problem doing it in different way than what I do due to my method does not cause for a vacuum bleed off or leak.

As we discussed along time ago Grant....when you asked me how to fix this and I left it up to you to figure out because you are so darn close to figuring it out without having a vacuum leak it is not funny Literally you are 99.8% there.. You just need to stop and think what you are trying to do. When you figure that out...which you have figured out the problem in the vacuum system and WHY this problem occurs.....AND you figured out the size of the tubes needed to fix it in the way you fixed it....then you will know WHERE to make you HIDDEN modification.

Here is another clue...and I am darn near giving the answer to you......."Consider the source". where this modification will correct EITHER the headlights or wiper door from coming UP when it is cranked. There is ONLY ONE PLACE to do this.

DUB

 

Hi DUB. I have a few of these faulty new relays collecting dust. On the worst one (from Corvette Central) the spring pressure is almost double that of the original 69 relay which has "AC Spark Plug Div" cast into the body. Since I don't have the equipment to crimp the ring I can't change the internal spring so my next experiment is to pull the foam filter and try an outer spring on the plunger end with a small plate bonded across the opening in the bottom to hold it up. Cut a small hole in the foam and put it back in. The outer spring would counteract the high pressure of the internal spring and nothing would be visible from the outside. My problem is finding the proper size/diameter spring. Lucky I have more than one junk drawer....

 

Grant,
Your are putting a lot of effort in the wrong area....but do as you wish..

I tack weld the crimped ring back on when I used to rebuild the actuator relays. Apply the tack weld and then put a soaking wet towel on it immediately. I sue one of those very thin stone discs that you can use with your Dremel tool to make the angled cut on the crimped ring if that is what you want to do.

You can also use some epoxy adhesive to hold the cut crimped ring also as long as you prep the surface as needed for maximum adhesion. I use a large radiator hose clamp to pull the ring back to where it need to be when I am tack welding it

YEAH...I have NUMEROUS junk drawers full of all kinds of 'goodies'.

DUB

 

I looked at it from another angle, the cold beer angle, and tried this today. I removed a spring from a spray bottle of bathroom cleaner, dropped it over the piston then slid a hacksaw blade over it just to try it out. It reduced spring pressure by about 50% and is very smooth. I'm going to bond a thin plate in there in place of the saw blade, install the filter and nobody will ever see it.

 

Okay, so I bonded in a piece of a starter shim with JB Weld to hold the spring and will put in the foam and install it in the car tomorrow after it cures to test it. This was the worst relay I have and seems to be very smooth and light now. Total cost so far is about 10 cents worth of JB Weld and a few beer. Plus I get to use something that was worthless before.

 

Great ingenuity but my concern is now you may have moved the internal plunger valve that routes the vacuum when it is needing to go to the top port to keep the door down....and it is possible that when you do not have vacuum on this actuator relay....it may not allow the headlight door to now open due to this newly added spring keeping this plunger up. You did not state if you tested that and it works out fine.

When I wrote "Consider the source"...What is the source that makes this system work at all. Then read what I previously wrote and use your previous idea that I wrote that is 99.8% correct in that location and it is fixed. Or at least all of the cars with entirely NEW vacuum system and parts...that is what fixed them all.

DUB