69 Headlight Switch-Vacum Leak
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Intermediate
Joined: Dec 2002
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From: Annandale VA
69 Headlight Switch-Vacum Leak
I had the shop replace the original swith because the interior light dimmer didn't work. New switch leaked air but the supplier sent a new switch. This one I put in myself (Thanks to CF and Stew), but it leaks also. Am I just lucky, is this a common problem with repro parts, or is something else going on?
Other details: Blue hose, closest to dash seems to have no vacum. The all black hose, closest to engine, has vacum and when I pull it off and put my finger on the end vacum is sealed and no 'hissing'. Put the black hose back on and leaking comes for metal body of switch. I've sprayed water onto the switch behind where the hoses attach and can hear some gurgling. Both new switchs act the same way. I put sealant on one of the switch bodies put no improvement. Growing weary of removing dash..... :confused:
Other details: Blue hose, closest to dash seems to have no vacum. The all black hose, closest to engine, has vacum and when I pull it off and put my finger on the end vacum is sealed and no 'hissing'. Put the black hose back on and leaking comes for metal body of switch. I've sprayed water onto the switch behind where the hoses attach and can hear some gurgling. Both new switchs act the same way. I put sealant on one of the switch bodies put no improvement. Growing weary of removing dash..... :confused:
Safety Car
Joined: Aug 2000
Posts: 3,943
Likes: 44
From: Florham Park NJ Port Credit Ontario
Re: 69 Headlight Switch-Vacum Leak (Jim69conv)
Jim, check the hoses that go from the Switch to the under dash switch.I have to doubt that TWO switches are bad. It has to be something minor.
I know about your woes. I had to pull my dash apart because I was a dummy and forgot to hook up my oil pressure guage :banghead:
Let me know how you progress.
Stew
I know about your woes. I had to pull my dash apart because I was a dummy and forgot to hook up my oil pressure guage :banghead:
Let me know how you progress.
Stew
Thread Starter
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Joined: Dec 2002
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From: Annandale VA
Re: 69 Headlight Switch-Vacum Leak (Stewart's74)
The under dash switches seem to be fine. I have to use the underdash override to open the headlights and the override for the windshield wipers still works fine.
In your experience, should the blue vacuum hose (closest to the dash) have any vacuum?
In your experience, should the blue vacuum hose (closest to the dash) have any vacuum?
Burning Brakes
Joined: Nov 2000
Posts: 948
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From: Johnston Iowa
Re: 69 Headlight Switch-Vacum Leak (Stewart's74)
Ok let me think this out with you:
When the headlight switch is closed vacuum should flow through the switch. So to test the switch if you plug one end and put a vacuum pump on the other it should hold vacuum when in the closed position. If it does then you have no leak. When you open the switch it should not hold vacuum. When vacuum is routed through the switch (closed)it pulls the spring loaded diaphram in the relay under the nose to the top which then directs vacuum to the rear of the headlight acuators keeping the headlights closed. When the headlight switch is pulled on or open that breaks the vacuum which cause the spring loaded diaphram to move to the bottom of the relay directing vacuum to the front of the acuators to make the headlights open. Do you have access to a vacuum pump?
[Modified by James, 3:17 PM 1/21/2003]
[Modified by James, 3:17 PM 1/21/2003]
When the headlight switch is closed vacuum should flow through the switch. So to test the switch if you plug one end and put a vacuum pump on the other it should hold vacuum when in the closed position. If it does then you have no leak. When you open the switch it should not hold vacuum. When vacuum is routed through the switch (closed)it pulls the spring loaded diaphram in the relay under the nose to the top which then directs vacuum to the rear of the headlight acuators keeping the headlights closed. When the headlight switch is pulled on or open that breaks the vacuum which cause the spring loaded diaphram to move to the bottom of the relay directing vacuum to the front of the acuators to make the headlights open. Do you have access to a vacuum pump?
[Modified by James, 3:17 PM 1/21/2003]
[Modified by James, 3:17 PM 1/21/2003]
Thread Starter
Intermediate
Joined: Dec 2002
Posts: 37
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From: Annandale VA
Re: 69 Headlight Switch-Vacum Leak (James)
"When the headlight switch is closed vacuum should flow through the switch. So to test the switch if you plug one end and put a vacuum pump on the other it should hold vacuum when in the closed position. If it does then you have no leak. When you open the switch it should not hold vacuum. When vacuum is routed through the switch (closed)it pulls the spring loaded diaphram in the relay under the nose to the top which then directs vacuum to the rear of the headlight acuators keeping the headlights closed. When the headlight switch is pulled on or open that breaks the vacuum which cause the spring loaded diaphram to move to the bottom of the relay directing vacuum to the front of the acuators to make the headlights open. Do you have access to a vacuum pump?"
Do not have a vacuum pump, but starting to sound like a good investment.
Leak only occurs when the headlight switch is pulled out (vacuum open), then I can hear the leak at the switch and it doesn't have enough 'whatever' to open the headlights without pulling the override.
Do not have a vacuum pump, but starting to sound like a good investment.
Leak only occurs when the headlight switch is pulled out (vacuum open), then I can hear the leak at the switch and it doesn't have enough 'whatever' to open the headlights without pulling the override.
Burning Brakes
Joined: Nov 2000
Posts: 948
Likes: 0
From: Johnston Iowa
Re: 69 Headlight Switch-Vacum Leak (Jim69conv)
Ok so I take it your headlights stay closed when the switch is closed?
You should have a break in the routing of the vacuum when the switch is pulled open that you might be able to hear. This is what causes that diaphram in the front relay to move to the position to pull open the headlights. Have you checked the relay under the nose to make sure it is working? You may need to start checking the lines that run to the front relay to make sure you have no leaks. An easy test of the relay is to start the car and pinch the skinny hose with the white stripe that runs to the top of the relay under the nose. This should cause the headlights to open if it is working correctly. You can pickup a hand held vacuum pump called the MightyVac from a number of different automotive stores pretty cheap or get a better one from Sears. By vacuum testing these lines it will assure you of no leaks. Let me know what you find out.
[Modified by James, 4:01 PM 1/21/2003]
You should have a break in the routing of the vacuum when the switch is pulled open that you might be able to hear. This is what causes that diaphram in the front relay to move to the position to pull open the headlights. Have you checked the relay under the nose to make sure it is working? You may need to start checking the lines that run to the front relay to make sure you have no leaks. An easy test of the relay is to start the car and pinch the skinny hose with the white stripe that runs to the top of the relay under the nose. This should cause the headlights to open if it is working correctly. You can pickup a hand held vacuum pump called the MightyVac from a number of different automotive stores pretty cheap or get a better one from Sears. By vacuum testing these lines it will assure you of no leaks. Let me know what you find out.
[Modified by James, 4:01 PM 1/21/2003]
Thread Starter
Intermediate
Joined: Dec 2002
Posts: 37
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From: Annandale VA
Re: 69 Headlight Switch-Vacum Leak (James)
Solution: Hoses at switch crossed.
I could swear that I had tried this but I guess not. After reading the above advice this seemed to be the logical problem. In my defense the shop that put the switch in and looked at it briefly before declaring 'drop it off and we'll take care of it' could have switched the hoses right then. I was sure that they knew what they were doing, and other instructions said carefully note current position of hoses, etc.
Thanks for everyones help. My lesson is if a knucklehead is going to work on my car, it might as well be me.
I could swear that I had tried this but I guess not. After reading the above advice this seemed to be the logical problem. In my defense the shop that put the switch in and looked at it briefly before declaring 'drop it off and we'll take care of it' could have switched the hoses right then. I was sure that they knew what they were doing, and other instructions said carefully note current position of hoses, etc.
Thanks for everyones help. My lesson is if a knucklehead is going to work on my car, it might as well be me.
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