Just got my 72 together. Everything is new and everything works. Except now the wipers. They worked perfect until I told my wife I was going to get the car inspected. Now they don't work. Or they worked when I closed the door hard and the wiper door opened and they worked. I guess I will check them tomorrow.

 

Did you check the connections on the wiper motor, or fuses? Sometimes on vintage cars, a light amt of corrosion is enough to stop things from working. Sometimes glass fuses can 'look' good, but I've seen where the filament inside can corrod on the inside metal caps (where where the fillament attaches). So you might want to check for voltage on both sides, or replace with a new one.

 

If the door opens and they dont work check the wiper override switch. Chances are you may have bumped it and just a little twist can shut it off. It happened to me and I had the wiper wiring under the hood disconnected before remembering that little .......then of course the connections, does the door open? If not then check the wiper switch it self and maybe run a seperate ground to it if your bezel is cracked

Rereading your post, slammimg the door and it suddenly works may indicate a loose connection, most likely a ground knowing how this system is put together....check all your connections. If you can have the motor running so you have enough vacuum to open the door, (or open it manually and then leave the key on and not running), then go wiggling wires, you'll find it and know it when the wipers pop up

 

Thanks for all the suggestions guys. I actually have a vacuum pump. Something has to be loose somewhere. The only thing that i did is I put the chrome ignition cover on. before that it was working fine. So maybe I hit something when I added that.

 

Rescue Rogers your great. I only have three things that weren’t working on the Lt1, the wipers, the clock and the trip Odometer. You fixed one in 10 seconds.

THANK YOU. I thought the motor had gone bad. Now can you help fixing the other two in the same easy fashion?

 

Everything worked fine, like I said I put the chrome ignition cover on and then I washed the engine compartment and then put a new filler neck on the wiper tank.
With the wiper door open the wipers work. On the door, it doesn't open even with the override. If I have it open and pull the override down the door will close. And then I can't get it open. There is only vacuum to the closed side of the canister. If i put vacuum to the other side of the canister the door doesn't open.


The door will close but not open. When I remove the hose that goes from the metal tubing to the wiper door vacuum switch valve the door will stay open. As soon as I put that hose back on the wiper door closes.

 

You would have to vent the actuator on the close side and add vacuum to the open side or it will fight itself which hose are you removing then reinstalling?

The good news may be that wiper washer tank is down in the passenger side fender correct? thats where mine is, its also where the wiper actuator relay is. Check and see if you you disconnected the small diameter vacuum hose with the white stripe, maybe you thought it was for the wiper washer.... If not then you may have done something to the actuator, they can be fragile.....

with the wiper switch off, see If all the hoses are connected and if you have a vacuum pump , use the guage and see if you even have vacuum on the open side of the actuator, red stripe hose, then see if you have vacuum on the black and white stripe line.. switch the wiper switch on n.... IF there is no vacuum on the black and white line then everthing is It probably working up to the actuator relay and it needs to be tested. Its easiest to test to see if the vacuum coming in on the black hose with the white stripe is actually there, than getting at the relay itself
http://repairs.willcoxcorvette.com/1...e-valve-works/

If vacuum issnt shifting from the red to green hoses then the relay may be leaking and you 'll have to pull it, along with your expansion tank if you have a small block

IF theres vacuum With the wipers in the on position to the top of the actuator relay on the small diameter hose with the white stripe, check it at the wiper arm vacuum switch under the wiper door. when the wiper is in the down position it should let vacuum pass, when its operating it stops the vacuum. Willcox has a test for it. Then check the vacuum at the solenoid on the tach and the bypass switch under the dash.


work backwards from K

THere will always be vacuum on G at Relay H coming in on the yellow stripe hose when the wipers are off
when the wiper switch is turned on,A vents vacuum and you wont have vacuum on K releasing the plunger. The plunger switches from the red hose to the green hose and you get openning vacuum, When there is vacuum on K, the the plunger is pulled up and vacuum is swithed back to the red hose

The relay actuator relays can go bad at anytime, so i wouldnt be surprised that it isnt the issue, especially since you where working near it, hopefully its just a hose

 

Start a new thread so we dont hijack this one and we'll try and figure it out...usually blowing all the dirt out of the clock will help using low pressure air. You have to pull down on the odometer **** when you turn it.....

 

Thank you for taking the time to explain these things to me. My car has a 502 in it. Original 454. car. I will check everything and get back ASAP. I will let you know what I am getting at each hose. 2 things I love about my 72. The chrome bumpers and the wiper door. And I think it adds to the car when it works right.

 

Been a little busy yesterday and today to check anything. I started about an hour ago and will continue Tuesday. I wrote down some findings but want to try them again tomorrow.

 

thats okay, we're not going anywhere.... apparently

 

Okay this is what i got today.

Door worked with bypass and the wipers came on. Everything off. I had vacuum at D. When hose was removed the door opened. And when reconnected the door closed.
K has vacuum with everything off.
G has vacuum
F no vacuum.

Now I went back to the bypass to try it again and it didn't work. The door stayed closed.
I opened the door manually and the wipers work and when the wipers are shut off they park and then the door closes.
Removed D from metal line and the door opens and when the hose is reconnected the door closes. I guess the vacuum switch that the wipers go down on is working.

 

I made amistake in my explaination of the system. I'll go back and change it after i answer you thread. So when the switch is off, K will always have vacuum, it holds the plunger up and keeps vacuum on H as long as the wipers are off. When the system is turned on, the k side is vented, the diaphram at the top of H is released and the plunger is pushed down and F gets vacuum and pulls open the door , the wipers move off the plunger it blocks the flow to K so that it wont get vacuum again until the wipers park. Thats why when you pull the bypass and you can here the vacuum leaking, its venting the air to H which lets the plunger drop to pull a vacuum on F. So as long as the switch is on you shouldnt have vacuum at H through K, D and B. You could test A and see if it vents when it is switch on. I was just looking at Willcox to see if there is a test for it. You could pull a vacuum on one side and block the other of it and then add power and see if it vents..

It sounds like you have an operating system but there is a bad connection or non funtioning switch at A possibly.

to address your tests
Door worked with bypass and the wipers came on. So the wiper switch was on, good. Everything from the bypass to the door is correect

Everything off.

I had vacuum at D. When hose was removed the door opened. And when reconnected the door closed. This sounds like its functioning fine from here to the actuator
K has vacuum with everything off. wiper switch off? This would be normal

So these following readings are with the switch off? I assume yes and these readings are normal
G has vacuum normal
F no vacuum. normal with switch off,
Turn the switch on and see if you have vacuum at K. It should be vented, If its there unplug it at A and see if the door opens and the wipers come on, If they do check A for power. If it does then pull the hose on the bypass side and put your finger on the bypass side nipple to feel for vacuum, if there is turn the wipers off and see if it changes, then turn it back on and see if the vacuum has changed.


Now I went back to the bypass to try it again and it didn't work. The door stayed closed.
I opened the door manually and the wipers work and when the wipers are shut off they park and then the door closes.
Removed D from metal line and the door opens and when the hose is reconnected the door closes. I guess the vacuum switch that the wipers go down on is working.
Im not familiar with the metal hose but if there is vacuum on it, pull the bypass and see if it goes away, maybe you either pulled the wrong bypass or it didnt open enough..... not sure, it should have gone away. But yes that wiper down switch doesnt sound like its malfunctioning.

Sorry about any of my obviously confusing info, someties I over think and get it backwards. You did good with your testing, We just need a definitve test for A and you sould be good to go. If we cant find one I'll try and pull mine out and test it

 

Just got done editting my last post. Just one easy test left

 

I found this at the end of a replacement tach solenoid description.....To test your old solenoid, apply power to one terminal and ground to the other side. When power and ground are supplied the solenoid should click and it should block vacuum from passing through itself.

Test your solenoid if it works while bench testing, hook the vacuum back up but not the plug from the wiper switch, then turn wiper switch on and see if when you apply power to the swotch like the bench test, the wiper doors opens. If it works check the power and ground at the tach solenoid connection, maybe you dont have a good ground

https://willcoxcorvette.com/corvette...solenoid-68-98
this one is unavailable
https://willcoxcorvette.com/corvette...solenoid-68-72

 

Thanks for getting back. Of course my luck has the hardest of the parts to get to might be bad. I will check that tomorrow.

 

good luck

 

My wipers were acting similar to yours a couple of months ago.
I could get the wipers to work if I got the door open but otherwise neither the wiper door nor the headlights were working properly...i was about to do a bunch of troubleshooting but then decide to check the wiper door actuator grommet because it had torn a couple of years ago.
It was the grommet on the aft side of the vacuum actuator that had slipped out. It's fairly new (~4+ years) so I cleaned everything up and then RTV'd in place..... then everything worked fine. I was lucky to not have to go into deep troubleshooting. Might be worth a look.

 

That metal vacuum line [running across the firewall] can be a problem. It has an angular 'dip' in it in the middle of that line. That is a spot where any condensation/moisture/dust/dirt can collect and form a blockage. Pull the hoses off BOTH ends and shoot some high pressure air thru there to clear it out. If you want to test for blockage first, put a hose on one end and blow gently thru it. If you get any resistance, you've found A problem. Maybe not THE problem, but certainly something that is amiss in the system.

 

I will also check that today. I did actually have that off 2 years ago when I restored the engine compartment. But worth a shot.