marshal135

Hello,
I've read all the great info on the headlight vac on this forum and I have a followup ?
I have 16-17 vac at the yellow line pulled off at the relay.
I have only 1 relay.(68)
I can move the yellow line directly to the green line pulled off at the relay and the headlights pop up. I can do the same on the red and have them drop.
Actuators appear fine and working just a little slow. Left 1st than right with direct vac guess they are a lil tired.
At the black hose w/ white stripe on the top hat I have 3-5 vac reading?
It seems too low to pull up the dog bone? Is my thinking correct?
I checked the 1 way valve and working according to test. Vac only running in one direction from the manifold.
No obstructions on the lil port or big port on 2 sided side.
I am connected to direct manifold vac. The filter is new. It is a '68 BB.
Does vac drop off that much at the top hat or is the overide switch shot?
I've replaced all the hoses from a hose kit for a '68. They are larger on the outside diameter than originals but fit snug on all connections. New tees as well.
I'm thinnking the relay if 3-5 vac reading is all the required amount to raise the dog bone?
Do I have a possible pinched small black line under the dash some where?
I will be getting a mighty vac to test relay before I purchase as Mike has strongly suggested in other posts.
Just not sure if the vac reading is correct?
Thanks,
Marshal

wombvette

Sounds like the valve is leaking.

...Roger...

3-5 is too low,sounds like you have a leak if the 3-5 is a direct and not a Tee'd in reading.

marshal135

The 3-5 reading is taken from the black line which would be connected to the top hat which runs directly from the over ride pull down not tee'd any where. Solid line.
I don't know if the leak is under the dash as a tee is there for spliting vac to wiper solenoid and head light switch. But 3-5 is definitely to low? Wombvette sorry I missed it, what valve did you mean? 1 way valve?
Thanks again,
Marshal

...Roger...

Is the problem that they work slow or not all ?

The system is tied together,if you have 16-17 on the yellow you should have close to the same on the black/white.

3-5 will usually move the dogbone but 3-5 tells me there's a problem somewhere

marshal135

Roger,
thanks for responding. The problem is they quit working.
Marshal

78IndyPace

You should have the same 16-17 vac reading here that you have at the large, yellow-striped hose. 3-5 vac might be too low to pull up the dog bone, but that also depends on the condition of the relay's diaphragm and/or of the dog bone itself and how much gunk may have accumulated that could interfere with its movement. You can test dog bone movement without a vacuum pump by connecting a hose (using a reducer T) directly from the vacuum reservoir to the relay's top hat then starting the engine. Keep the large yellow-striped hose connected between the reservoir and the large middle port on the relay. The headlights should retract or stay retracted. Remember to block any hoses and ports that you disconnect.

Refer to Figure 1 in my original post of this thread:

How Your Headlight Vacuum System Works

While your '68 has one relay rather than the two shown, operation is the same.

Your low-vacuum-at-the-relay-top-hat problem lies somewhere between Circle 1 and Circle 2. You have a significant vacuum leak, a blockage (pinch?), or an incorrect connection somewhere in that part of your system. If your wiper door is working, then the problem is somewhere after the T where the wiper door control line is connected.

Easy Mike

New check valve? It could be installed backwards.

7T1vette

Either the headlight relay is leaking so much that there isn't enough left to work the lights [the yellow hose is the supply hose and your testing proved that there is enough on that to do the job], or the headlight switch is damaged or has lost a hose from a fitting. You should pull the 'signal' hose off the top of the headlight relay, stick a vacuum gauge on that line and actuate the headlight switch in the car. If it doesn't 'flip' between 0" Hg and 15" Hg (approx.), then you know where the problem is.

marshal135

7T1Vette,
which signal line are you refering too? Top hat line(black w/white stripe)?
78IndyPace,
I'll jump the yellow supply line w/ reducer tee to top hat nipple on relay
and see if they open. They are down now. I jumped the red to yellow and lowered them where they remain. They do not open on own even though the lights are illuminated facing downward.
I hope its not the head light switch that looks like a bitch to change
Thanks,
Marshal

wombvette

The signal line is the small one, and it just switches vacuum on or off. The system is fail safe to the up position so whether the inside switches are working or not will not make any difference, the lights should come up if you pull that signal line off. The relay valves are prone to leak, and the vacuum actuator boots on the headlights are prone to seal failure.

...Roger...

Marshal,if you have the engine running and remove the small black/white stripe hose from the tophat , do the lights come up ? They should pop up.

marshal135

I'll try to pull off the line and report back
Marshal

7T1vette

You should be trying to determine if that [top hat] signal line can supply the proper vacuum signal when you turn the headlight switch ON and OFF. I would choose to stick a gauge on that line (instead of hooking it to the relay) and turn the light switch ON and OFF to see what the vacuum signal does. But, you can test it however you want. If you get no change on that line when the switch is activated, nothing will happen with the lights.

marshal135

7T1Vette,
thanks for clarifying it for me. That's what I'll do I'll pull a vac reading from signal line w/ headlight switch off (should be zero), I guess and on
pulled out all the way and let you know what I found.
I'm leaning towards the relay but do not want to throw parts at it wantanly.
Thanks Again,
Marshal

...Roger...

No ,HL switch in the off position should show full manifold vacuum
HL switch pulled out or ON should show 0

Thats why I ask what the lights do with the small hose pulled off and the engine running.

0 vac to the tophat should make the lights come up if the relay is working correctly (and the hoses are in the correct positions).

marshal135

Gentlemen,
here is the results of my testing:
I started the car and warmed it up.
I checked for full manifold vac at the check valve.
I had 17 on the large port, 5 on the small port leading to inside dash?
I can not blow through the 2 ported side but can suck through the single ported side alt big and little ports on 2 sided end of valve. Both sides allowed suction when the other port was covered. Pass testing right?
I by passed the check valve(removed) and ran full manifold vac through small hose leading into dash.( large yellow hose to tank left off) I connected vac guage at signal line at relay end.
I received 17 vac reading and when I shut the car off the vac guage
went down very slowly not rapidly. It looks like the dash components are holding vac. I pulled the headlights switch on with the engine running and vac guage dropped to 2 , same results with pull down overide activated.
When I tee'd the yellow line in at check valve end by passing check valve vac dropped to 5 again at the signal line end.
I ran car and disconnected signal line again with all components hooked up and the head lights did not rise.
I can only raise and lower by by passing relay and applying dierct yellow line full vac to either the green to rise or red to lower.
This is where I'm at???
I'm not running out and buying a bunch of replacement parts till I isolate the problem.
Awaiting Help
Thanks,
Marshal

7T1vette

Maybe you stated the results in your post somewhere...I'm not sure. It's clear that when you pulled the headlight switch ON you got 2" Hg on the gauge; that would certainly indicate that the vacuum signal was LOW under those conditions. But, I didn't really see the result you got when you pushed the headlight switch back in [OFF].

Now, if I just didn't catch the results, but the headlight switch successfully toggled between HIGH vacuum and LOW vacuum when it is exercised, then your problem MUST be a very leaky [or defective] relay valve. Perhaps it is frozen up internally and can't move (or something to that effect). However, if the signal line also gets 2" Hg when that headlight switch is turned OFF, then the headlight switch is the problem...or a hose has come off of that switch.

marshal135

7T1Vette,
headlight switch off 17 on guage, switch on 2 so slight leak possible in headlight switch. Same results when pull down activated wiper side of system fine. I'm thinking also relay is frozen up inside.
I saw Wilcox has them the cheapest anywhere at $34.00
Thanks for all your help
Marshal

marshal135

From what I can gather by trial and error and testing it's the relay.
I ordered a new relay for the head light actuators from Wilcox.
Seems to be the problem. It acts frozen inside.
All other components responding as accordingly
I'll let u know how I make out
Marshal