another wiper/vacuum system question
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 19
Likes: 0
another wiper/vacuum system question
Hi guys,
I purchased a 70 vette and have been slowly nursing it back to health. I replaced all the vacuum hoses, filter and check valve and the wiper arm control valve. I now have a wiper door that opens and wipers that come on (most of the time).
Is it normal for the vacuum system to "decompress" after about a minute of the car being off? The lights stay down but the wiper door was coming up about an inch. I lengthened the wiper door actuator arm (by unscrewing the bolt) and now the door is a little low but stays closed after I hear a click and air escaping from the valves..
Or do I have a vacuum leak?
Any input would be appreciated!
Noob
I purchased a 70 vette and have been slowly nursing it back to health. I replaced all the vacuum hoses, filter and check valve and the wiper arm control valve. I now have a wiper door that opens and wipers that come on (most of the time).
Is it normal for the vacuum system to "decompress" after about a minute of the car being off? The lights stay down but the wiper door was coming up about an inch. I lengthened the wiper door actuator arm (by unscrewing the bolt) and now the door is a little low but stays closed after I hear a click and air escaping from the valves..
Or do I have a vacuum leak?
Any input would be appreciated!
Noob
Pro
Joined: May 2006
Posts: 573
Likes: 5
From: Georgetown Township MI
I have the exact same problem with my 70'.
Tonight I opened the hood to "listen" for an air leak and sure enough
I heard it. It's either at the 3 way valve or the rubber hose coming off of
the intake to it.
Joe
Tonight I opened the hood to "listen" for an air leak and sure enough
I heard it. It's either at the 3 way valve or the rubber hose coming off of
the intake to it.
Joe
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 19
Likes: 0
Well, I ordered a new vacuum actuator valve(4 ports) the other day and will replace the old wiper one and see if that helps. I can't really hear air leaking from anywhere.
Joe, when you say 3 way valve, do you mean the one under the passenger wiper? That is brand new along with the hoses and I have adjusted it so that when the wipers are down, it is definitely closed tightly.
In your 70 vette, is there a screw in the vent hose in the "safety control valve" under the wiper? It was in mine and I saw one other pic online. I took it out as all the vacuum kits guides online do not have this.
Joe, when you say 3 way valve, do you mean the one under the passenger wiper? That is brand new along with the hoses and I have adjusted it so that when the wipers are down, it is definitely closed tightly.
In your 70 vette, is there a screw in the vent hose in the "safety control valve" under the wiper? It was in mine and I saw one other pic online. I took it out as all the vacuum kits guides online do not have this.
Last edited by pyro454; Aug 10, 2011 at 03:56 PM.
Safety Car
Joined: Sep 2005
Posts: 4,062
Likes: 103
From: Southeast, Tennessee
St. Jude Donor '09 thru '26
i'd bet on it. there shouldn't be any hissing sound that you can hear with the engine running or not. you might want to double check the vacuum reserve can. many of the older C3 models had nothing more than a reasonable facsimile of a #10 fruit can for the reserve tank and they had a tendency to rust out easily. if the tank is ok, check to see if you can hear where the hiss is coming from. the switch directly under your steering column is designed to manually open the system (to change the blades or to wash the headlamps) without running the engine. it gets it's "power" from the reserve tank. if there is a leak, there will be no reserve (obviously).
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 19
Likes: 0
So I got the vacuum actuator valve relay and replaced the wiper one near the firewall. It did not help so I then moved it up front to replace the one I heard a "click" coming out of after the car was off. Problem solved.
Wiper Door on my 70 C3 goes up and down nicely now! (I just need to find out why the wipers won't come on now!!)
Wiper Door on my 70 C3 goes up and down nicely now! (I just need to find out why the wipers won't come on now!!)
Team Owner
Joined: Sep 2006
Posts: 31,267
Likes: 4,362
From: Westminster Maryland
Hi p,
Have you checked the limit switch that's on the firewall and operated by the wiper mechanism. It's function is to NOT let the wipers start until the door is fully open.
Here's a picture of the switch.
Do you have a headlight/wiper trouble shooting guide?
Regards,
Alan
Have you checked the limit switch that's on the firewall and operated by the wiper mechanism. It's function is to NOT let the wipers start until the door is fully open.
Here's a picture of the switch.
Do you have a headlight/wiper trouble shooting guide?
Regards,
Alan
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 19
Likes: 0
(oh and if that's you engine compartment, it is imaculate!)
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Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 19
Likes: 0
Well, I finally had a chance to remove the switch and test it with an Ohm meter. Works perfectly. I also bypassed the safety switch with a wire and then turned on the wiper switch and I can hear a click sound but have no wiper action... is a new wiper motor the next step?
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Check the over-ride switch under the dash before you do anything, its right between the two vacuum switches under the column.
Then: Go here and click on supporting document.
Corvette Windshield Wiper Motor Wire Schematic 69-72 with test
http://willcoxcorvette.com/repairand...elp.php?hID=95
Next, go watch the bench testing video....
Here is a picture of the three way valve or "Check" Valve.
Video thread is here.. http://forums.corvetteforum.com/c3-g...post1578797422
Then: Go here and click on supporting document.
Corvette Windshield Wiper Motor Wire Schematic 69-72 with test
http://willcoxcorvette.com/repairand...elp.php?hID=95
Next, go watch the bench testing video....
Here is a picture of the three way valve or "Check" Valve.
Video thread is here.. http://forums.corvetteforum.com/c3-g...post1578797422
Last edited by Willcox Corvette; Sep 26, 2011 at 10:46 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If I'm not mistaken, the wiper interlock valve/switch does vent vacuum when the engine is shut down. If the system is not 'leak-free', the wiper door might go up a bit after a few seconds due to vacuum in the system not being retained as it should. But, otherwise, the vacuum items operate as they should. This is just one of the symptoms of a system with normal wear in seals/valves.
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
Well, I ordered a new vacuum actuator valve(4 ports) the other day and will replace the old wiper one and see if that helps. I can't really hear air leaking from anywhere.
Joe, when you say 3 way valve, do you mean the one under the passenger wiper? That is brand new along with the hoses and I have adjusted it so that when the wipers are down, it is definitely closed tightly.
In your 70 vette, is there a screw in the vent hose in the "safety control valve" under the wiper? It was in mine and I saw one other pic online. I took it out as all the vacuum kits guides online do not have this.
Joe, when you say 3 way valve, do you mean the one under the passenger wiper? That is brand new along with the hoses and I have adjusted it so that when the wipers are down, it is definitely closed tightly.
In your 70 vette, is there a screw in the vent hose in the "safety control valve" under the wiper? It was in mine and I saw one other pic online. I took it out as all the vacuum kits guides online do not have this.
http://forums.corvetteforum.com/c3-g...trieval-5.html