Wiper door actuation help needed
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 5,253
Likes: 768
From: Waterford WI
Wiper door actuation help needed
Wiper door isn't opening on the 1970 with 62k miles that is running for the first time since 1980. This is the "70 barn find revisited" car. Here's what's happening:
Headlights open and close fine.
I hear no vacuum leak anywhere. Engine is 350/350 and idles fine at 700 rpm.
Wiper door doesn't open either from the wiper switch or the override switch under the dash.
When I manually open the door, the wipers work, and as soon as I turn them off, the wipers park and the door closes.
Because the car is untouched and unmolested, I'd rather not touch anything unnecessary. Any suggestions on where to look? I've read through the guide on the whole system, but would rather have someone point me to a more specific starting point.
Thanks for your help!
Headlights open and close fine.
I hear no vacuum leak anywhere. Engine is 350/350 and idles fine at 700 rpm.
Wiper door doesn't open either from the wiper switch or the override switch under the dash.
When I manually open the door, the wipers work, and as soon as I turn them off, the wipers park and the door closes.
Because the car is untouched and unmolested, I'd rather not touch anything unnecessary. Any suggestions on where to look? I've read through the guide on the whole system, but would rather have someone point me to a more specific starting point.
Thanks for your help!
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
sounds like the vac motor is bad. maybe the relay. got a vac guage? check for vac signal at motor at the hoses. should have vac in switch position off, then switch to wiper on,recheck for vac signal at other hose. if ok then bad vac motor. if not then bad vac valve. also check to MAKE SURE you have a vac signal to the valve in one position. there are also hoses and solenoid inside, if the above doesn't fix it get back to me and I'll work you throught the rest of the system. T
Team Owner
Joined: Sep 2006
Posts: 31,235
Likes: 4,326
From: Westminster Maryland
Hi 62,
Try reversing the green and red hoses on the relay. Does the door now open but not close?
Put the hoses back where they were on the relay and try reversing the red and green hoses on the actuator. Does the door now open but not close?
Do you have a mity-vac tool? With it you can test the actuator and relay individually with them still in place.
Regards,
Alan
Try reversing the green and red hoses on the relay. Does the door now open but not close?
Put the hoses back where they were on the relay and try reversing the red and green hoses on the actuator. Does the door now open but not close?
Do you have a mity-vac tool? With it you can test the actuator and relay individually with them still in place.
Regards,
Alan
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
If you follow me on this, we can get your wiper door working like new. 
Because you have control vacuum to the relay closing the door, or keeping it closed, we know that portion of the system works. Reason is that the default position is door open with no control vacuum to the relay. The relay is passing actuating vacuum to the front port of the actuator because the door is closing when signaled. What is not working is the actuating vacuum to the rear of the actuator which would open the door. There is a rubber seal on the actuator rear shaft that holds vacuum inside it. The seal is probably kaputski........Very common on old original survivor type cars. If the bellows is still on the actuator rear shaft, simply pull it towards the firewall. Look at the condition of the shaft seal, I bet it is shredded. You can also hook up a Mityvac to the rear port and try to pump it down. It should hold vacuum. You can also apply lung vacuum to the port if you do not have a Mityvac. It won't take much to determine the problem.
This is step one. If you need step two, let me know......
btw, nice car, I have 2 '70 L46's myself
Because you have control vacuum to the relay closing the door, or keeping it closed, we know that portion of the system works. Reason is that the default position is door open with no control vacuum to the relay. The relay is passing actuating vacuum to the front port of the actuator because the door is closing when signaled. What is not working is the actuating vacuum to the rear of the actuator which would open the door. There is a rubber seal on the actuator rear shaft that holds vacuum inside it. The seal is probably kaputski........Very common on old original survivor type cars. If the bellows is still on the actuator rear shaft, simply pull it towards the firewall. Look at the condition of the shaft seal, I bet it is shredded. You can also hook up a Mityvac to the rear port and try to pump it down. It should hold vacuum. You can also apply lung vacuum to the port if you do not have a Mityvac. It won't take much to determine the problem.
This is step one. If you need step two, let me know......
btw, nice car, I have 2 '70 L46's myself
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo