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Discussion Starter · #1 ·
I still haven't got all the parts to put the entire RS hideaway headlights together but I'm trying to test the canisters to see if they're any good. They are brand new repros but have never been used for at least 4 years now. I tried to hook the vacuum line straight off the manifold to either side of one and it doesn't move the plunger in or out. If I hold my finger over the other fitting for a little bit and then let it go the plunger jumps in or out about an inch. is there any valid way to test them? If I get a vacuum pump/gauge, how much vacuum should I have?
 

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Discussion Starter · #3 ·
Man, at $90 a pop that stinks. Do you know how much vacuum it should have? Maybe that's the problem.?
 

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Discussion Starter · #5 ·
Sounds great Carl. I just ordered a new relay valve, actuator brackets etc to put it all back together. When I get all that I'll assemble it, then take vacuum readings at the canisters, and if it matches your readings then I'll get new canisters.
I guess there's nothing one can do to free up the sticking new ones? WD40?
 

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Discussion Starter · #6 ·
CarlC, if I could ask one more favor while you're working on an RS today. Someone emailed me a diagram of the hose routing in response to my post asking if I got it right and in his diagram it says the hose that runs from the light switch back to the very top fitting on the relay will have vacuum present only when the light switch is pulled out. I tested mine by blowing into one of the hoses that goes to the switch. If the switch is in (off) I get air out of the hose going to the relay. If the switch is out (off) I can't blow through it. Dosen't that sound backwards from his description? If so, could my switch be backwards or the hoses on wrong? Seems like that would be a simple open/close switch but maybe it could be turned around on the light switch housing?
 

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I wish I had better news for you on the repro relay valve; they are just as bad as the actuators. They leak out of the bottom of the mechanism. I'm still on the lookout for a really good original part. The repro will get the job done but it just sucks that the quality is so poor.

WD40 did not help either the old or new repro acturators that I tried it on.

If my ailing brain remembers correctly vacuum is applied to the relay to make the actuators open. In the normally closed position there is no vacuum available. I'll double check. I don't think it makes much difference which side the engine vacuum line attaches to the light switch. It's just an on-off slide valve.

I won't be able to take vacuum readings at the cannisters but can get one at the reserve tank.



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The Red Beast http://www.geocities.com/casanoc
 

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It does matter which side the manifold vacuum attaches to the light switch.If it's on the wrong side, it will leak.I just went out and checked my car,there is vacuum at the head light switch hose,at the top of the valve,with the light switch off.If you pull the hose off the valve,the headlights open.I had problems with my new actuators,but found I had the hoses at the head lt switch reversed,and the tank couldn't develop enough vaccum.It sure sounds like your actuators are too stiff.I feel as long as they hold vacuum,they should work.I don't know if WD40 is ok to use on rubber,maybe some Armorall would work,and run it back and forth by hand a bunch.

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68 z28 ,68 rs 327 ,73 454 vette, 2 goofy kids
 

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Discussion Starter · #10 ·
Man this is not encouraging, so the relay valve repros are no better? How do you know when one leaks? can you hear it or feel it? If it's around the housing can you use cilicone calk to seal it up?
Dale what you described makes sense. I think my hoses going to/from the switch are on correct.
One more question: should there be a check valve between the manifold and tank on 68 or just a filter? My hose kit came with a filter and instructions that said there was no check valve on a 68 but there should be one on a 69,
 

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My 68 has a check valve,I it is essential,if you want your doors to open quickly,after you start the car.I'm using the repro canisters and relay valve,they work flawlessly(if you take out the I am an idiot factor)The relay valve is just a spool valve connected to a rubber diaphram on top.The top port is to the rear of the canister,my hose is green.The rear of the canister pulls the doors closed When vacuum is supplied to the diaphram,it pulls the spool valve up,connecting the supply port(center) to the top port.You could check the relay valve for a vacuum leak by sucking on the center port,and covering the lower port.If it holds vacuum,it doesn't leak.Pull a vacuum on the upper diaphram,this will pull the spool valve up,connecting the center and top port.Try the same test,if it holds vacuum,it's good. This is really a simple system,easy to test,if you understand how it works. I took apart my origional relay valve,and sealed it up by "shimming" up the lip seal inside.It worked great,didn't leak anymore,to bad the canister on the right side leaked,and the hose clamp I used to clamp the valve back together was ugly.The "hole" on the bottom of the valve needs to be there,it is ableed to atmosphere,without it the system wont work properly. You can use the check valve for a 69,it is installed near the master cyl. The hose that is t'd into the supply line (tank to valve) will go to the check valve,instead of the Tee.Just run a straight piece of hose (no Tee) from the tank to the valve.

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68 z28 ,68 rs 327 ,73 454 vette, 2 goofy kids

[This message has been edited by dale68z (edited 04-29-2001).]
 

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Discussion Starter · #12 ·
Dale, thanks fot the info. It sounds like it ought to be simple to test for leaks. I'm still confused on where your the check valve is. Maybe you can look at another post I put out just the other day. I detailed how I understand the routing to be. I thought the check valve would go in the supply between the manifold and the small fitting on the tank. Then the large fitting on the tank goes to the yellow (middle) fitting of the relay valve but it has a Tee that connects a small hose to the light switch. The other hose on the light switch then comes back to the top of the relay. Is that correct? Appreciate the help.
 

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Dale,

Sound like you had good luck with with the relay valve. I've had the unfortunate experience of having to deal with three of them. Each one leaked at the bottom of the valve so badly that I could hear it leak while the engine was running. At a car show in Burbank last week I was talking with a guy who has a 1969 RS Z-28 car that is one of the nicest cars I have ever seen. He's gone so far as to trim the lengths of vacuum tubing so that each actuator opens at the same time! He too has had bad experiences with the relay valve.

It may be hit or miss on the actuators. The ones that I bench tested and confirmed worked smoothly work great in the car. I tried using my power vacuum pump for 1/2 hour to loosen up the sticky ones but had no luck. I tried several different lubricants but again had no luck.

I believe the check valve goes on the manifold line just before the lines that go through the firewall. The valve has two output connections, one goes to the T on yellow line (between the relay and tank) and the other to the light switch.

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Winch,you are correct on the vacuum.If you use the 69 check valve(3 port),you will loose the Tee,between the reserve canister and check valve.The 68 check valve is a 1 in 1 out,valve(2 port).
 

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Discussion Starter · #15 ·
Ah nuts, now I'm even more confused. So the check valve goes in the small line that goes from the light switch to the Tee thats in the large yellow hose between the tank and the relay? I sure would have it would be in the hose from the manifold to the tank. Seems like that would be the appropriate place to keep from losing vacuum when the engine is off.
Also I'm confused between what is a filter and what is a check valve. Year One shows a picture of what I got with my hose kit but calls it a filter on one page but a check valve in the index. Are they really the same thing?
 

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I know I have a problem when I respond,I ramble to much.The check valve goes between the manifold and the tank.On a 69 the check valve has 2 output hoses,one to the tank,the other to the head light switch.I havn't seen the 68 check valve in the repro cataloges.They do sell the 69 check valve.I saw a similar check valve on a 82 corvette,just the other day.The filter just keeps the air passing thru the hoses clean.This might be a preventive maintenence item.(changed every so many years)The assembly manual has the hose routing in it.If you don't have one,it is very helpful.The check valve and filter are 2 different things that are installed in the intake manifold, to tank,hose.

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68 z28 ,68 rs 327 ,73 454 vette, 2 goofy kids
 

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Discussion Starter · #17 ·
Ok I think it's starting to sink into this ailing brain. I need a check valve but so far I haven't found one for a 68. I may have ordered a relay valve when I don't need one. I have the original but the center connection was broke off. I inserted a small piece of copper tubing and put JB Weld all around it. It seems to hold but when the whole system didn't work I assumed I had a bad relay. Maybe not. I noticed by sucking on the top fitting I could hear the diaphram go up. I also noticed that if I blow into the center fitting while holding my finger over the bottom I feel air coming out the bottom. Somewhere I read a response that said that is normal - it's an air bleed? I'll test the new one I get and if it works the same I'll send it back (I hope they'll take it back!).
What I've got to do is get a vacuum pump and gauge and hook it all together and just see what I've got where and when. I still need to know how much vacuum is normal.
Also since right now it's not all hooked up, I just have 2 hoses going to/from the light switch. I suppose I could still hook them up wrong. Dale, since you say it matters, is there a way to tell which goes to which fitting on the light switch? Do you have to pull the switch out to see it? I haven't climbed under there to see if I can see it w/o pulling it out.
Thanks guys
 

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Discussion Starter · #18 ·
I just bought a MityVac vacuum hand pump and gauge. I can't wait to see how it works. The book says a normal engine will pull 16-22" hg of vacuum so I assume that's what should be required to open those canisters. I'll let you know what I find out. Also I didn't realize how many different diagnostic test you can perform with one of these.
 

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Discussion Starter · #19 ·
Well what tests I could perform weren't very encouraging. Checking the vacuum straight from the manifold I get a steady 19. The needle vibrates a lot but doesn't fluctuate. Hooking the gauge to the large output from the reservoir I get a steady 19 that climbs to 20-22 when engine reved. When I turn the engine off it slowly but steadily drops to zero in about 2 minutes (is that normal or does it indicate a leak?).
I then hooked the gauge to one of the lines going to the headlight switch. I can hold the other line and pump it up to 20 and it then will drop steadily to zero in about 20 seconds (leak somewhere in the switch or hoses to/from it?). That s*(&^(* switch is above the astro ventilation and looks like it will be a bear to get to. Then I checked the relay valve I have. It doesn't hold vacuum at all. You can hear it sucking air in from the bottom.
I did discover I have a check valve in the hose from manifold to tank and it seems to work!
I'm beginning to wonder if this is worth it.
 

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If I remember right,the hose that goes to the tee is the rear most port on the head lt switch.The switch is easily accessed thru the astro vent.Pull out the vent,easy!If you have a check valve,it doesn't sound like it's working,since the vacuum drops that quickly.The vacuum part of the light switch can be taken apart.There is a rubber seal and a flat spring in there.

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68 z28 ,68 rs 327 ,73 454 vette, 2 goofy kids
 
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