I’m getting 15 at the end of the hose that would plug into the valve. The larger nipple on the valve reads higher than the small nipple. The small nipple is what is giving vacuum to the relays downstream and their in lies the problem. Not enough vac to the relays to keep the plunger up and activate the closing side over the actuators.

 

It's one of those things that I replaced when I did the engine compartment....detail thing....kinda pissed me off....but I just took the original one and stuck it in a media tumbler at work. Now it looks too good. Lol.
BTW...I never run the filter either....troll me if you like but you are not going to suck anything in there to cause the engine to explode.....and how is it going to get past the check valve anyhoo?

Jebby

 

If you pull the 2 lines off the check valve and attach a mighty vac to each of them and pull a vacuum, you should be able to isolate the 2 systems. If you can hold vacuum in one line, that system is not leaking. Try them both. Keep headlight switch "off" and keep the pull down valve in the "up" position.

The black hose coming off the check valve going into the firewall grommet is the supply for the "control signal" and the other hose coming out of the check valve going to the front of the car is the "actuator power" line. These 2 systems are independant.

The black vacuum control signal line going thru firewall grommet goes in to the headlight switch and then out of the switch as a blue line going down to the pull down switch before heading back out of the passenger compartment as a white line to the front of the car. This control line works by RELEASING (leaking) the vacuum out to the atmosphere. If you pull out on the headlight switch, the vacuum is released to the air and the loss of vacuum in the "control" line will cause the headlight doors to OPEN while the electrical part of the switch lights the bulbs. If you want to open the headlight doors without the bulbs lighting up, you pull down on the under dash valve and the control signal vacuum is released to the air. Zero vacuum in the signal line opens the doors either way.

check both systems to be sure they hold vacuum first.

I recently found my control signal line circuit leaking. Headlights would not open. I found the 2 hoses on the headlight switch were reversed. I attached them according to the assembly manual first BUT that diagram seems to be wrong. Another poster here confirmed this. Reversed those 2 hoses on the switch and everything works fine now.

I hope this helps.

 

good advice here. Thanks. If I remember right when I used the mv to pull vac from the smaller hose going through the firewall to the headlight switch it did not hold. I’m starting to think maybe the hose is too loose at the headlight switch. Does anyone know if this should be a very tight connection? When I plug mine in it’s surprisingly easy to put on. I’ll check this today.

 

Yes!

Those 2 hoses should be snug but not crazy tight. Just tight enough to not leak. You might need to cut off a half inch to see if it snugs up a bit.

If that system is not holding vacuum, you have found the first issue. Your headlights will not work until you fix this.

If the black hose to the headlight switch is connected wrong you can swap those 2 lines (black hose and blue stripe hose). When hooked up wrong, this part of the control system will not hold vacuum. Your sidepipes will drown out the vacuum leak sounds. Worth a try.

Before you do that...if you can attach your mighty vac to the white hose coming out of the pull down switch and see if it holds vacuum. If that line holds vacuum, the problem is not up front - It is inside the passenger compartment. Then you can try swapping those 2 hoses at the headlight switch.

 

I’ve spent the last 3 hours on this and still no solve. I will try to see if it holds vac from the white hose from the pull down. I did however verify 16 inches at all points from the source all the way to the pull down. From the pull down is where it failed with no vac. I bypassed the pull down to see if the hose connection at the t to the relays was getting vac and it did get 16 inches too. I thought I had found the culprit but when I tried to use the head lights car running still not working. I know the relays are moving up to activate the red hoses to the actuators but no cigar. Only thing I have left to verify is the two yellow hoses going to the center nipples of the relays. I’m pulling hair out over here. Damn!

 

I don’t get it. If I know the relays plunger are pulled up because they are getting 16 inches vac and I know the yellow hoses are getting 16 inches vac why the hell don’t the actuators close the lights?? What am I missing here??

 

The vacuum relays might 'move', but they are notorious for leaking internally.

 

Relays work. Just checked them again. The new check valve doesn’t supply vac to both nipples. It will only supply vac to one or the other when the other is plugged. Is this normal?

 

No.
Vacuum should go to both nipples. One goes to the vacuum reservoir and the other goes inside the cabin for HVAC 'stuff'. They BOTH need to function all the time.

 

well for some reason only one works when the other is plugged. I guess I got a brand new dud.

 

Hang in there Bluesting !

 

It happens. Part quality has come to the point that I do a functional test on everything I buy BEFORE I install it. I can't do functional testing for 'strength', so I just buy the better quality parts at higher price for a brand with better credentials. And if I buy it at a local parts store, my intent would be to check it at the store before I pay for it. (Can't do that on mail-ordered stuff, however.)

 

I don't understand, in post 47 OP says 16" at relay actuator and yellow hoses.
Depending on what nipple side (large or small) of the check valve is blocked or defective, how can you have 16" at both the relay actuator (Signal Vacuum/Small Nipple) and the yellow hoses (Feeding Reservoir Tank/Large Nipple)?

 

Been at it again for the last few hours and and losing hope here. I used a little silicone spray in the new relay valves just to make sure it was lubed up. That helped a little. I currently have bypassed the tank with a t. Bypassed the pull down connecting directly into the light switch and have gotten 16 inches again at the t before splitting to the relays. 16 inches at each supply line going to the middle nipples of the relays. Took out the headlight switch and tested again. They “worked” one time very slowly then would not come back down. The relay valves are getting 16” so I don’t understand why they would come back down.

 

Are you sure the canisters are ok?

Jebby

 

if you mean the actuators, yes. Rebuilt them and tested several times. I can’t explain it. Vac going to both main supply lines, going to the relays and headlight switch checks out. I can’t explain it. I feel like I know this design like the back of my hand now but can’t figure out where it’s going wrong. Going to contemplate it for a few days. I may just need to plan on electric. I’m really trying to save the money and keep the vac system especially since I almost never actually use the headlights.

 

Your relays are BAD and leaking internally. To prove this, just remove the yellow striped (center nipple) hoses from the relays and plumb them directly to the OPEN side (or the other) of the headlamp actuators. Then fire up the engine. The headlamps should pop open as soon as engine is fired. Shut down engine and plumb the [yellow] vacuum hoses to the other side of the actuators. Fire engine and headlamps should quickly close. If all that happens as expected, REPLACE THE WORN-OUT RELAYS.
P.S. The lube shot into the relays "helped" because it temporarily blocked some of the leakage flow past the internal shuttle valve (with worn out seals). But after the lube dried out, they still acted the same....correct?

 

the relays are brand new. I did test them too. I think the lube helped because they probably weren’t lubed to begin with at manufacturing.

so tonight I took it for a nice drive. Got dark so tried the lights. They flipped open although slowly. Got home to shut them and nothing. I’m pretty sure it has to be no vac to th relays now. WTH. That tested ok yesterday so maybe I’ll retest.

I am starting to wonder if these new relays maybe the problem though. I did test test before install though. I’m just at a loss.

 

Tomorrow I’m going to plug my vac gauge to one end of the relay vac line and the other end to my mighty vac to see if that line maybe leaking. It’s the one thing I think I haven done.