headlight relay valves
Thread Starter
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
headlight relay valves
I’m trying to teach myself how this works, but my car is not nearby so I am looking at the AIM.
Each relay assembly has 4 ports. The 3 lower ports contain the valve; the middle connects to the engine manifold, the top and bottom connect to the headlight actuator. The upper port is the actuator that controls the valve.
My questions are about the valve’s actuator control. Does this receive vacuum only when signaled to open the headlights or vice versa? Is the actuator spring loaded to the top or bottom? Is the other side of the diaphragm balanced internally, vented to atmosphere, or sealed?
Each relay assembly has 4 ports. The 3 lower ports contain the valve; the middle connects to the engine manifold, the top and bottom connect to the headlight actuator. The upper port is the actuator that controls the valve.
My questions are about the valve’s actuator control. Does this receive vacuum only when signaled to open the headlights or vice versa? Is the actuator spring loaded to the top or bottom? Is the other side of the diaphragm balanced internally, vented to atmosphere, or sealed?
Last edited by Turbo-Jet; Apr 18, 2005 at 03:09 PM.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
In the control system(the part of the system that gives the instruction), the absence of vacuum causes the positive operation. So when vacuum is removed from the valve, the headlights(or wiper door) open.
There are four hoses: 1) the control system vacuum hose; 2) the operating system vacuum supply; 3) The vacuum from the valve to the vacuum motor to open the mechanism, and; 4) the vacuum from the valve to the opposite side of the diaphragm to close the mechanism.
There are four hoses: 1) the control system vacuum hose; 2) the operating system vacuum supply; 3) The vacuum from the valve to the vacuum motor to open the mechanism, and; 4) the vacuum from the valve to the opposite side of the diaphragm to close the mechanism.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Originally Posted by CGGorman
The diaphragm housing has a spring in it... I took apart both of mine last fall and rebuilt them. Easy and it cost me about $0.18.
Cost has gone up.... from $0.15... LOL
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
To rebuild these relays, the hardest part is getting the ring that holds the upper half to the bottom half, off. When you get them apart you can see the spring under the metal cap that pushes the valve back to the closed postion when no vaccum is to the small upper port. The middle port on the valve body is where engine vaccum is applied at all times. The upper port is to raise the headlights when the vaccum is applied to the small upper port. The bottom port is to drop the headlights when the vaccum is taken away from the small upper port.
Drifting
Joined: Apr 2003
Posts: 1,323
Likes: 2
From: Castle Hills Texas
Originally Posted by PhotoVette1
I got rid of the vacuum relays and installed the solid brass vacuum relays that are used on McDonalds hamburger grills; they're indestructable and fit in the same location--so invisable.
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
Any Taylor Freezer parts distributer; it's a model 32 grill. The valves operate on 12 VDC, so, when headlights are on, the valves are energized and the doors open.
I also use a small air compressor from an air horn instead of engine vacuum. This allows me to raise and lower the headlights with the engine off. easy hookup, just reverse the vacuum lines.
I also use a small air compressor from an air horn instead of engine vacuum. This allows me to raise and lower the headlights with the engine off. easy hookup, just reverse the vacuum lines.
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Drifting
Joined: Apr 2003
Posts: 1,323
Likes: 2
From: Castle Hills Texas
That is ingenious! How did you stumble onto the McDonald's fix? Surely you didn't look at it and say "Hey, I think model 32 grill vacuum relay will solve my problems." I really am curious as to how you came to the grill parts fix and am not trying to be a smartass.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
In the control system(the part of the system that gives the instruction), the absence of vacuum causes the positive operation. So when vacuum is removed from the valve, the headlights(or wiper door) open.
There are some good schematics in the shop manuals. I'll see if I can get a scan and post it...
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
Originally Posted by Z-man
Acutally, the headlights close when vacuum is applied to the OTHER side...
There are some good schematics in the shop manuals. I'll see if I can get a scan and post it...
There are some good schematics in the shop manuals. I'll see if I can get a scan and post it...
Pro
Joined: Aug 2003
Posts: 673
Likes: 0
From: Jackson Ms
this site is good for vacuum troubleshooting.
think it a fourm member's site. click on vacuum troubleshooting.
helped me a lot.
http://www.corvette-101.com/
think it a fourm member's site. click on vacuum troubleshooting.
helped me a lot.
http://www.corvette-101.com/
Thread Starter
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Originally Posted by gerry72
In the control system(the part of the system that gives the instruction), the absence of vacuum causes the positive operation. So when vacuum is removed from the valve, the headlights(or wiper door) open.
There are four hoses: 1) the control system vacuum hose; 2) the operating system vacuum supply; 3) The vacuum from the valve to the vacuum motor to open the mechanism, and; 4) the vacuum from the valve to the opposite side of the diaphragm to close the mechanism.
There are four hoses: 1) the control system vacuum hose; 2) the operating system vacuum supply; 3) The vacuum from the valve to the vacuum motor to open the mechanism, and; 4) the vacuum from the valve to the opposite side of the diaphragm to close the mechanism.
This is what I was thinking. So the 'off’ position of the valve is to 'open' the headlights due to and internal spring? This is because there is no vacuum in the control hose (engine off, vacuum depleted).
Interesting to observe that the headlights do not pop up then close when the engine is first started. This is because there is some delay in vacuum reaching the valve (and therefore the actuator) as it takes a few seconds to evacuate the reservoir tank which is before the valve. The control line does not include the reservoir and therefore evacuates rather quickly.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Originally Posted by Tom454
I did some too...
Cost has gone up.... from $0.15... LOL
Cost has gone up.... from $0.15... LOL
A link some have posted:
Headlight relay repair
http://iotech.no/corvette/index.htm
Just using some black RTV will work instead of adding an o-ring.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Originally Posted by wcsinx
I believe he was strictly referencing the relay. Removing vacuum from the control port will have the affect of opening the lights.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
Originally Posted by PhotoVette1
Any Taylor Freezer parts distributer; it's a model 32 grill. The valves operate on 12 VDC, so, when headlights are on, the valves are energized and the doors open.
Drifting
Joined: Mar 2003
Posts: 1,608
Likes: 3
From: Canberra AUSTRALIA
St. Jude Donor '05-'06
Originally Posted by PhotoVette1
Any Taylor Freezer parts distributer; it's a model 32 grill. The valves operate on 12 VDC, so, when headlights are on, the valves are energized and the doors open.
I also use a small air compressor from an air horn instead of engine vacuum. This allows me to raise and lower the headlights with the engine off. easy hookup, just reverse the vacuum lines.
I also use a small air compressor from an air horn instead of engine vacuum. This allows me to raise and lower the headlights with the engine off. easy hookup, just reverse the vacuum lines.
You better show us some pics! (and part numbers)
Pete