68 Wiper Door Vacuum
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Joined: Oct 2004
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From: Bowling Green KY
68 Wiper Door Vacuum
Good Morning Everyone!!!
I've been pulling my hair out trying to find what I assume is a vacuum leak on my vette. It's a 68 car that I recently had the dash out of, so im suspecting that the problem is behind the dash, but not sure. I've checked every switch and connection I could find.
Basically what happens is that when I start the car, the wiper door opens, and stays open, you have to push it back down by hand once the engine is shut off to get it to close. The headlights work perfectly, this is my only problem,,,,,,
There's a solenoid mounted to the back of the tach that has (going off of memory) a vacuum hose with a white (or gold) stripe going into the top, and one with a blue stripe coming out of the bottom.
Any help would be greatly appreciated!!!
Scotty
I've been pulling my hair out trying to find what I assume is a vacuum leak on my vette. It's a 68 car that I recently had the dash out of, so im suspecting that the problem is behind the dash, but not sure. I've checked every switch and connection I could find.
Basically what happens is that when I start the car, the wiper door opens, and stays open, you have to push it back down by hand once the engine is shut off to get it to close. The headlights work perfectly, this is my only problem,,,,,,
There's a solenoid mounted to the back of the tach that has (going off of memory) a vacuum hose with a white (or gold) stripe going into the top, and one with a blue stripe coming out of the bottom.
Any help would be greatly appreciated!!!
Scotty
Instructor
Joined: Jul 2007
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Before you do any serious digging, make sure you haven't activated the switch that keep that door open. I don't recall exactly which one it is, but directly below your steering column (you can hit it with your shins), there are a couple of pull switches. One of them it there to keep that door open. You may have it activated and just need to push it (or pull it??) to deactivate it.
Safety Car
Joined: Feb 2006
Posts: 3,557
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From: Ridgeway VA
I have a '70 so it should be the same. The relay under the RH wiper
controls the door opening/closing. First, make sure the RH wiper is
firmly down on the "button" top part of the relay. If not check the
LH wiper to see if it is preventing the RH from going down all the way.
If OK could be the relay itself. My problem after I took the dash out was
I hooked the solenoid hoses backward. Lots of great more detailed
threads on the search function.
controls the door opening/closing. First, make sure the RH wiper is
firmly down on the "button" top part of the relay. If not check the
LH wiper to see if it is preventing the RH from going down all the way.
If OK could be the relay itself. My problem after I took the dash out was
I hooked the solenoid hoses backward. Lots of great more detailed
threads on the search function.
Thread Starter
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Joined: Oct 2004
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From: Bowling Green KY
Does anyone know which hoses go where on the wiper vacuum solenoid, or if it matters? I believe right now I have the Black/yellow going in the metal barb, and the Black/blue going in the bottom plastic barb. I think that this plastic barb is a T and has one side that stays open.
Thanks!
Thanks!
Racer
Joined: Mar 2007
Posts: 321
Likes: 1
From: Melbourne Florida
Before you do any serious digging, make sure you haven't activated the switch that keep that door open. I don't recall exactly which one it is, but directly below your steering column (you can hit it with your shins), there are a couple of pull switches. One of them it there to keep that door open. You may have it activated and just need to push it (or pull it??) to deactivate it.
My limited experience with the wiper door is that the vacuum solenoid switch must be activated. When activated, it routes vacuum into the door cannister to pull the linkage and thus open the door. I think the 68 cannister is different than the 69 (mine) but I think the operation is the same. Pull the vacuum hose off the back side of the cannister (towards the wiper door) and feel for vacuum while the car is running and the wiper is off. If there's a vacuum, the solenoid switch is allowing it to go there and is likely the culprit.
Having said all that, I've had strange experiences with mine that defy logic. I know if the vacuum reserve cannister located just behind the left front wheel hasn't stored enough vacuum, weird things happen. My car doesn't really function correctly with the vacuum operated devices for at least 3 to 4 minutes after start up. My buddies' 69 comes to life within 8 or 10 seconds. I must have a vacuum leak somewhere.
Drifting
Joined: Jul 2004
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From: Kissimmee fl
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You said you had the dash out. Make sure that the plug on the wiper switch is hooked up properly. It can be pushed on 180 deg. out with very little effort.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Does anyone know which hoses go where on the wiper vacuum solenoid, or if it matters? I believe right now I have the Black/yellow going in the metal barb, and the Black/blue going in the bottom plastic barb. I think that this plastic barb is a T and has one side that stays open.
Thanks!
Thanks!
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Drifting
Joined: Oct 2004
Posts: 1,255
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From: Coralville Iowa
I assume you have checked the most obvious vacuum problems and are still in the weeds. If so....
There is a small needle valve in the electric solenoid behind the dash that gets stuck open. I rebuilt mine. Your dash wiper switch electromagnetically activates the needle valve in the solenoid. The needle valve has a very small return spring. The small foam filter that is put on the end of the inlet get lost or falls out allowing small bits of dust, smoke, and anything else that is behind the dash to be sucked in causing the valve to stick. Once you pull it apart and free the needle it will work fine. Use a small piece of foam hepafilter on the end after you put it back together. I believe you can now purchase a replacement solenoid aftermarket which might be easier than a rebuild. I have a tech sheet on the rebuild somewhere... I will try to find it.
There is a small needle valve in the electric solenoid behind the dash that gets stuck open. I rebuilt mine. Your dash wiper switch electromagnetically activates the needle valve in the solenoid. The needle valve has a very small return spring. The small foam filter that is put on the end of the inlet get lost or falls out allowing small bits of dust, smoke, and anything else that is behind the dash to be sucked in causing the valve to stick. Once you pull it apart and free the needle it will work fine. Use a small piece of foam hepafilter on the end after you put it back together. I believe you can now purchase a replacement solenoid aftermarket which might be easier than a rebuild. I have a tech sheet on the rebuild somewhere... I will try to find it.
Thread Starter
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Joined: Oct 2004
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From: Bowling Green KY
I'll give these things a look and see what happens!!
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Sounds like I have the Yellow hose in the right place, but the blue is not. The blue is on the straight barb rather than the 90* barb. It's really hard to get to, so I wasn't thinking about it when I was trying to get it stuck on there. I'm 99.9% sure that the connector is on the solenoid correctly, but will it really make a difference, I think I tried it and it would work both ways,,,,,,,
I'll give these things a look and see what happens!!
I'll give these things a look and see what happens!!
Edit-That was stupid of me. You have to use the side port the other port is what dumps the vacuum.Thats whats stopping your flow of vacuum from getting to the relay valve under the hood.
Last edited by ...Roger...; Dec 6, 2007 at 02:12 PM.
Burning Brakes
Joined: Oct 2001
Posts: 911
Likes: 5
From: TN
wiper switch
Precaution- I have a original owner 68 and have only done it twice and the results were the same. When my 68 is not being used and during cleaning of top of the dash the wiper switch got moved to the on position. I moved it back and finished cleaning. Left the car sit for several days and had a dead battery. The movement of the wiper switch caused the drain. This is my 68's gremlin. To make things right if the switch is moved, the only way to do it is to start the car and cycle the windshield wipers and turn off with the the car running. Has anyone else experienced this on a 68? My 70 has no reaction if the wiper switch is turned on/off when the ignition is OFF.
Thread Starter
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Joined: Oct 2004
Posts: 62
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From: Bowling Green KY
Precaution- I have a original owner 68 and have only done it twice and the results were the same. When my 68 is not being used and during cleaning of top of the dash the wiper switch got moved to the on position. I moved it back and finished cleaning. Left the car sit for several days and had a dead battery. The movement of the wiper switch caused the drain. This is my 68's gremlin. To make things right if the switch is moved, the only way to do it is to start the car and cycle the windshield wipers and turn off with the the car running. Has anyone else experienced this on a 68? My 70 has no reaction if the wiper switch is turned on/off when the ignition is OFF.
Thread Starter
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Joined: Oct 2004
Posts: 62
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From: Bowling Green KY
I'm not totaly sure of whats inside the 90*.Maybe Highschool can tell us if it is just an open 90 or if the needle valve only effects ONE of the 2 ports. I probably have a solenoid valve I can look at if he doesnt respond.
Edit-That was stupid of me. You have to use the side port the other port is what dumps the vacuum.Thats whats stopping your flow of vacuum from getting to the relay valve under the hood.
Edit-That was stupid of me. You have to use the side port the other port is what dumps the vacuum.Thats whats stopping your flow of vacuum from getting to the relay valve under the hood.
Sounds like that might be where my problem lies!! I'll move it around tonight and see what happens! Thanks for everyone's input!!
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
I have heard of the black **** on 68s causing drain if left in the bypass mode.
Drifting
Joined: Oct 2004
Posts: 1,255
Likes: 7
From: Coralville Iowa
I assume you have checked the most obvious vacuum problems and are still in the weeds. If so....
There is a small needle valve in the electric solenoid behind the dash that gets stuck open. I rebuilt mine. Your dash wiper switch electromagnetically activates the needle valve in the solenoid. The needle valve has a very small return spring. The small foam filter that is put on the end of the inlet get lost or falls out allowing small bits of dust, smoke, and anything else that is behind the dash to be sucked in causing the valve to stick. Once you pull it apart and free the needle it will work fine. Use a small piece of foam hepafilter on the end after you put it back together. I believe you can now purchase a replacement solenoid aftermarket which might be easier than a rebuild. I have a tech sheet on the rebuild somewhere... I will try to find it.
There is a small needle valve in the electric solenoid behind the dash that gets stuck open. I rebuilt mine. Your dash wiper switch electromagnetically activates the needle valve in the solenoid. The needle valve has a very small return spring. The small foam filter that is put on the end of the inlet get lost or falls out allowing small bits of dust, smoke, and anything else that is behind the dash to be sucked in causing the valve to stick. Once you pull it apart and free the needle it will work fine. Use a small piece of foam hepafilter on the end after you put it back together. I believe you can now purchase a replacement solenoid aftermarket which might be easier than a rebuild. I have a tech sheet on the rebuild somewhere... I will try to find it.
Cleaned the solenoid and has worked perfect ever since. Had the same problem with my 69. Same fix and it has worked ever since.
Here is an exploded view. It makes and breaks vacuum depending on the
wiper switch. The only hard part of the dissasemble/reassembly is drilling out the extra small rivets and finding small enough screws,nuts and lockwashers to put it back together. It needs to be "vacuum" tight.
Make sure that you but some type of filter on the open end. It is drawing vacuum and will suck in every small dust particle behind the dash. (Not much dust behind a dash on a 40 year old car!! )
Hope this helps.
Last edited by highschool67; Dec 7, 2007 at 12:57 PM.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
My entire light/wiper vacuum system on my 68 worked fine except the wiper door never closed.
Cleaned the solenoid and has worked perfect ever since. Had the same problem with my 69. Same fix and it has worked ever since.
Here is an exploded view. It makes and breaks vacuum depending on the
wiper switch. The only hard part of the dissasemble/reassembly is drilling out the extra small rivets and finding small enough screws,nuts and lockwashers to put it back together. It needs to be "vacuum" tight.
Make sure that you but some type of filter on the open end. It is drawing vacuum and will suck in every small dust particle behind the dash. (Not much dust behind a dash on a 40 year old car ) :>)
Hope this helps.
Cleaned the solenoid and has worked perfect ever since. Had the same problem with my 69. Same fix and it has worked ever since.
Here is an exploded view. It makes and breaks vacuum depending on the
wiper switch. The only hard part of the dissasemble/reassembly is drilling out the extra small rivets and finding small enough screws,nuts and lockwashers to put it back together. It needs to be "vacuum" tight.
Make sure that you but some type of filter on the open end. It is drawing vacuum and will suck in every small dust particle behind the dash. (Not much dust behind a dash on a 40 year old car ) :>)
Hope this helps.
Last edited by ...Roger...; Dec 7, 2007 at 01:05 PM.
