vacuum switch behind tach
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 29
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vacuum switch behind tach
I've been working on my '72 and it's vacuum system for some time now. With all the hoses attached in the right places, the wiper door comes up when the engine is started even though the wiper switch is in the "off " position. Some time after the engine has been shut off, you can manually push the door back down, but not while the engine is running. I have replaced many of the hoses and all the valves but not the wiper door opening canister. My logic tells me that since the wiper door opening/closing canister opens the door, then the diaphram inside must be ok, so I haven't messed with that.
I guess the last thing to try is the valve or switch that sits behind the tach. I found a link to where a guy said to drill out the rivets and clean and rebuild the unit, but I'd rather replace the thing if it's available. I don't ever remember seeing one on ebay, so that's kind of scary. Can't find one in any of my Corvette catalogs from various companies. I'd really like to hear from anyone who has fixed their wiper door problems or knows where to get this switch/valve.
thanks
Denny
I guess the last thing to try is the valve or switch that sits behind the tach. I found a link to where a guy said to drill out the rivets and clean and rebuild the unit, but I'd rather replace the thing if it's available. I don't ever remember seeing one on ebay, so that's kind of scary. Can't find one in any of my Corvette catalogs from various companies. I'd really like to hear from anyone who has fixed their wiper door problems or knows where to get this switch/valve.
thanks
Denny
Last edited by djohan; Oct 17, 2005 at 08:17 PM.
Pro
Joined: Dec 2003
Posts: 631
Likes: 0
From: Northern Virginia
check this thread out, i havent ordered one yet for my car so let me know if they work thanks
http://forums.corvetteforum.com/show....php?t=1194938
-Bob
http://forums.corvetteforum.com/show....php?t=1194938
-Bob
Advanced
Joined: Aug 2004
Posts: 83
Likes: 0
I got one(wiper door solenoid) from:
Piper's Auto Specialties, Inc.
308 Water Street
PO Box 140
Vermilion, Il. 671955-0140
217-275-3742
I found out that these aren't made anymore so the one I got was used and it bench tested o.k. I had my system working fine and all of a sudden, the wiper door started coming open when I started the car. Still haven't figured what's wrong.
The solenoid is expensive-cost me $100 plus S & H. In my case the solenoid isn't the problem. Before you spend the $$$ bench test yours to see if it's bad.
Hope this helps, Roger B.
Piper's Auto Specialties, Inc.
308 Water Street
PO Box 140
Vermilion, Il. 671955-0140
217-275-3742
I found out that these aren't made anymore so the one I got was used and it bench tested o.k. I had my system working fine and all of a sudden, the wiper door started coming open when I started the car. Still haven't figured what's wrong.
The solenoid is expensive-cost me $100 plus S & H. In my case the solenoid isn't the problem. Before you spend the $$$ bench test yours to see if it's bad.
Hope this helps, Roger B.
Instructor
Joined: Aug 2002
Posts: 203
Likes: 0
From: Anaheim Caleefornia
Don't forget to check the vacuum relay for the wiper door. That is if you haven't replaced it already. Some are down near the right side fender vents and others, like mine, are high on the firewall near the brake booster. If that relay is either leaking or stuck, it may be causing the door to stay open.
That little vacuum switch has never given me any trouble (which means it will fail tomorrow).
Good luck with your repairs.
SharkPilot
That little vacuum switch has never given me any trouble (which means it will fail tomorrow).
Good luck with your repairs.
SharkPilot
Racer
Joined: Dec 2002
Posts: 421
Likes: 2
From: Long Grove, IL
Originally Posted by djohan
I've been working on my '72 and it's vacuum system for some time now. With all the hoses attached in the right places, the wiper door comes up when the engine is started even though the wiper switch is in the "off " position. Some time after the engine has been shut off, you can manually push the door back down, but not while the engine is running.
Regards,
Jay
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 29
Likes: 0
wiper door problems
Jay...
I did replace most of the hoses that I could get to easily. I have a steering column mounted vacuum gauge which shows about 17inches of mercury at idle. That is plenty vacuum to pop the headlights up with gusto so there doesn't seem to be a significant leak in the system.
I went over all the hoses again last night to make sure they weren't switched and all checked out fine. Like I said in my earlier post, the valve on the back of the tach is just about the only thing I haven't changed, along with the vacuum motor(canister) which actually opens the wiper door.
I'm very stumped.
Denny
I did replace most of the hoses that I could get to easily. I have a steering column mounted vacuum gauge which shows about 17inches of mercury at idle. That is plenty vacuum to pop the headlights up with gusto so there doesn't seem to be a significant leak in the system.
I went over all the hoses again last night to make sure they weren't switched and all checked out fine. Like I said in my earlier post, the valve on the back of the tach is just about the only thing I haven't changed, along with the vacuum motor(canister) which actually opens the wiper door.
I'm very stumped.
Denny
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Dr Rebuild used to have some NOS ones, but I heard they are all gone now. You could use a fan control solenoid for a big truck. I think it is just a normally closed 12v solenoid valve. Try your local Mack, Kenworth, Peterbilt, Freighliner,Navistar, etc. store in the parts dept. Or you might look online, I believe Horton or Kysor are 2 manufacturers of them.
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
Originally Posted by djohan
I've been working on my '72 and it's vacuum system for some time now. With all the hoses attached in the right places, the wiper door comes up when the engine is started even though the wiper switch is in the "off " position. Some time after the engine has been shut off, you can manually push the door back down, but not while the engine is running. I have replaced many of the hoses and all the valves but not the wiper door opening canister. My logic tells me that since the wiper door opening/closing canister opens the door, then the diaphram inside must be ok, so I haven't messed with that.
I guess the last thing to try is the valve or switch that sits behind the tach. I found a link to where a guy said to drill out the rivets and clean and rebuild the unit, but I'd rather replace the thing if it's available. I don't ever remember seeing one on ebay, so that's kind of scary. Can't find one in any of my Corvette catalogs from various companies. I'd really like to hear from anyone who has fixed their wiper door problems or knows where to get this switch/valve.
thanks
Denny
I guess the last thing to try is the valve or switch that sits behind the tach. I found a link to where a guy said to drill out the rivets and clean and rebuild the unit, but I'd rather replace the thing if it's available. I don't ever remember seeing one on ebay, so that's kind of scary. Can't find one in any of my Corvette catalogs from various companies. I'd really like to hear from anyone who has fixed their wiper door problems or knows where to get this switch/valve.
thanks
Denny
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Burning Brakes
Joined: Apr 2003
Posts: 844
Likes: 0
From: Central KY
Dec 05 Corvette Fever...
...has an article in there about vacuum systems. They touch on this issue briefly. Speaking of replacement parts - the white plastic inline air filter for your hose running to your intake manifold vacuum fitting... I have put two or three on my car. They just split in half - poorly glued together! I super glued my latest one and am waiting to see how long it takes to split in half again. Crappy part! I hope the replacement solenoids are better for you...
Last edited by djcwardog; Oct 19, 2005 at 02:56 PM.
Instructor
Joined: Jan 2004
Posts: 101
Likes: 0
From: New Orleans Louisiana
Search on Ebay
Denny,
I too searched on Ebay for the vacuum switch. I never saw one BUT I did find a guy selling a tach that had the switch still attached. So I bought the extra parts just to get the switch and it works. If you can't find your switch somewhere else, start checking the tachs for sale on Ebay.
Ken
I too searched on Ebay for the vacuum switch. I never saw one BUT I did find a guy selling a tach that had the switch still attached. So I bought the extra parts just to get the switch and it works. If you can't find your switch somewhere else, start checking the tachs for sale on Ebay.
Ken