7T1vette

I believe so. When the interlock valve is depressed (wiper parked), the vacuum supply line should not be 'vented' at all. When you turn off your car, you should not hear any "hiss" from that valve. If you do, the valve isn't fully depressed...or it is defective. My guess is that the interlock valve and/or the parked wiper blade are not properly oriented to each other.

0Willcox Corvette

Ccrane,

I think you now have a great concept of the door and the controls that make it work and only a few things come to mind here. Roger, Alan, 7t1 and all others that have posted have posted good info for all to share in the future. I’ve been pre-occupied the past few weeks and I just now got a chance to look at this.

One thing that comes to mind is that you can do a by-pass test to see if the switch or the arm adjustment is the problem by by-passing the switch. To bypass it, simply route the red stripe hose to the black/white stripe hose. You can use your over-ride in the dash as the new interrupt switch for the system if needed. I’m only telling you this to confirm there is a problem with either the valve or the arm adjustment.

If you by-pass and the door is not jumping up and down, then yes, you have nailed the problem to this area.

Next as 7t1 stated, you can do a blow/suck test on the valve to see if it’s working properly. Do this on the car and you will know if the problem is the wiper arm adjustment of the switch. If you do the blow/suck test on the car and the valve fails, remove if from the car and test it off the car. If it works off the car, then your problem is an adjustment problem.

Now this may/may not be a problem that can be solved with trying to adjust the valve. It could be a problem with the wiper arm. If the arm is slightly tweaked, of if the wiper transmission is worn you will not get proper seating on the arm and thus the valve may be leaking down inadvertently. I've seen cars come in the shop in the past with rubber strips glued to the wiper arm. One of my cars had this problem and the PO just glued a strip of thin rubber on the arm. The system worked fine with it, but it looked. . . well it looked like Bubba and the transmission was the actual problem.

Roger is on some house sitting sabbatical in the sunny Fl, and I don’t think he has internet service, so I though along with 7T1, I would inject my thoughts. I have not read this entire post but I’ll try to do this on Saturday. I’ll have some time then and see if I can help you further.

Alan: I’m working on new schematics with diagnosis for all to have, but it like other things this week have been put on the back burner.

7T1, you help a ton of people here. . . Just want to say thanks; kind people are what make this forum a good place for everyone.

Personally and not to jack this thread: I’ve spent most of this week trying to help a customer at our shop understand why he has a 61 worth about 40k that needs 7K worth of work and he has over 128k in. Yes you read right!

Oh. . . we just got the car this a few weeks ago and he has yet to spend 1 cent with us. Long story short is he got Jacksoned on a fake car and then paid another 48k to a street rod shop to do a destoration. . . I’m taking plenty of pics and will do a post on C1-2 when we get it all together. It really is a sad story!


Willcox Inc.

CCrane65

Wow, thanks Willcox. You've given me a lot of additional information. I never thought to watch the transmission linkage to see if it was sloppy. I have had that problem in the past, about 3 years ago but had long since forgotten about it. At that time I only had to tighten up some bolts to fix it. Seems that many of the lock washers on this car are flat from age.

I went to try testing the switch and the battery was dead so it's sitting on the charger now. Tomorrow if the battery is holding a charge I'll test the vacuum through the switch.

I will also bypass the switch and see if the door pops up and down or not.

cc

0Willcox Corvette

Cliff,

Just a hunch. . . But try this and see. I'll be online a little tomorrow but for sure on Sat. . . So post again. . . I'll try to cover for Roger. Ha Ha!

Willcox

CCrane65

I pulled the red striped and white striped hoses off the interlock switch and jumpered them together and the door still popped up and down when I started the car. So the leak is somewhere else I take it?

cc

0Willcox Corvette

Yep! It has to be somewhere else if you removed the switch from the system.

I'll try to look this over tonight and if not tomorrow. I'll only be short on time tonight.

Willcox

CCrane65

More information from testing - I did the blow test with the switch installed and with the wiper up and locked on the windshield the red port blocked air passage while the white port passed air, with the wipers down and parked both the white and red ports passed air.

There are only 2 components left and I'm afraid it is the solenoid that is failing to hold vacuum.

Just for grins I switched the hoses on the override switch around and there was no affect that I was able to detect.

cc

...Roger...

I've been following when I can but I haven't been successful at posting,and believe me I have tried. I hope I can get this message to actually post. I'm on dial up.
CCrane try the 2 tests in this thread.
http://forums.corvetteforum.com/c3-g...inch-test.html
In the first test in this thread hold the pinch for up to a minute and see if that will cause the wiper door to come up-- if it doesnt come up then the solenoid is not leaking.
If the door doesnt come up on the first test then go to the #17 post and and do that test. If this test keeps the door from popping up on start up then the check valve is leaking.

FB007

The only significant thing he changed that changed function was the check valve. The new repop unit is bad. Change it again.

CCrane65

According to these last 2 tests, the new check valve is bad. I put the old one back on knowing it is bad but apparently it is not leaking at as high a rate as the new one since the door only raised about 1/2" then went back down.


Thanks all for your help and DWncchs, you have a friend for life so anything I can do the help you sometime all you have to do is name it.

I wish I could get you high speed internet because I know how much of a pain dialup is.

Willcox as always your help and information is invaluable and you can expect an order for a check valve soon.

FB007, only one post but you nailed it thanks.

cc

0Willcox Corvette

CC,

No problem! You can check the valve too! Do you have a mighty vac? If so you can put it on there and see if it's leaking down. Also a quick check but not as accurate. You should be able to blow thru it in one direction and not the other too!

If the valve came from me, shoot me an email and I'll have one sent out on Monday NC.

Willcox

CCrane65

Willcox, this was not one of yours so not to worry. I have a mini car vacuum but the opening is too large for testing these types of parts and I have no idea if it is too much suction.

cc

cc

7T1vette

Just clean both ends and suck! Actually, that will tell you if the check valve is OK or not. It should pass air one way and seal off on the other. If it doesn't seal completely (some leakage gets through), the valve is junk. Then you need to install it in the correct direction...the end which passes air [when you suck] goes toward the intake manifold fitting.

CCrane65

I just blew through the check valve and it seems to work the way it needs to. You can blow through the two port side but not through the single port side.

That would be right for vacuum.

cc

7T1vette

That's correct. But, the 'blow' side is the 'downstream' side (toward the vacuum reservoir).

...Roger...

The 2nd test shows the valve is definitely bad. There are varying degrees of "bad".

Very glad you got to the bottom of the problem and happy I could help. Do you happen to know a good workers comp attorney in the state of Florida ? While volunteering at a state park I got hit with a backhoe,launched into the air, through a hedge,rope fence , breaking a 4X4 and landed on my back in a parking lot. Its been almost 4 months and W.C. has chosen to ignore me.

Big pain but I'll be home to my HS in a week or two (should have bought an air card).

As I said above the leaking varies. If your using the "blow" test on the single port side blow very easy don't blow hard. The aftermarket check valves seem to pass the quick hard blow test but not the slow easy blow test. "Its the slow easy test that counts."
If I can get my pics from Photobucket to load I will post a dissected check valve and you will see its just a flat piece of rubber that is doing the "checking" of vacuum. This is the 3rd time I have tried to post this response.Here we go again !!!

...Roger...

Here is a check valve opened up. As you can see the single port side is the check side the 2 port side is just an open "T". Its just a rubber wafer , its not like a tapered valve with seat and a spring to apply pressure. To make matters worse when the wafer seeps slightly the vacuum in the reserve tank slowly draws the gasoline fumes from the hot engine through the check valve damaging the wafer and into the vacuum system where the fumes sit an attack the other components.

CCrane65

I wish I did. That really sucks. They're probably ignoring you because Florida is a socialist state. Everybody gets the same crappy healthcare etc.


Air cards are wonderful. I introduced them to my company in 2003 when Sprint was the only one offering them. I had executives reporting that they were checking email from a duck blind.


I went out and tried the soft blow and really didn't notice any leakage. What I'm struggling to understand is when you shut off the engine, is the intake manifold vacuum maintained? I would think not since there are large openings through the carburetor. With the valve allowing air through towards the engine I would think that would evacuate the entire system rather quickly.

cc

...Roger...

NO manifold vacuum is maintained when the engine is shut down.

The engine or intake side of the check valve goes to 0 vacuum when the engine is shut down and this is when the check valves operation comes in to play.


Just to clarify --test #2 in the other thread was to:
have engine running,
pinch hose between check valve and engine,
while maintaining the pinch on the hose have a helper shut engine down,
wait a min. or so (still pinching the hose) have helper restart the engine,
if the door pop up problem is gone then the problem was the check valve was leaking back.
You might have to try the suck method to prove your valve is bad. "On the 2 port side" - block with your thumb the small port and suck lightly on the larger port. You will most likely find you can sneak vacuum past the check valve when you suck lightly but when you suck hard the valve seals up.

CCrane65

DWncchs, I modified test 2 slightly by using 2 flat pieces of metal and a pair of vise grips to pinch the hose since I didn't have a helper handy.
But I got the same result. The door stayed shut.

cc