Vacuum relay valves leaking. Normal? Rebuildable?
Thread Starter
Team Owner
Joined: Jun 2004
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From: Smile, it's just the internet.
Vacuum relay valves leaking. Normal? Rebuildable?
Hooked a vac pump to the wiper/headlight system this morning and found both relay valves to be leaking past the "piston". The diaphragms are OK. Is this leak normal? I'm assuming not... Can they be rebuilt? I didn't have enough time before leaving for work to study them. Besides, after finding the leaks I figured I'd just buy replacements . Replacements are like $60 ea, though. I'll spend the money if I have too, but it's too much to simply accept if there is a possibility of a rebuild.
Le Mans Master
Joined: Aug 2000
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From: Brazos TX
Cruise-In IV Veteran
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I did the same test on mine a few years ago. Leaking is not normal. I used to have a link to someones site that detailed a repair of the piston. It involved using RTV. I think the last time I tried visiting the site it was down. I usually repair things like this as well but I didn't feel like messing with it. So I just bought new ones and now my headlights really work great.
Team Owner
Joined: Mar 2002
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Originally Posted by burners
I did the same test on mine a few years ago. Leaking is not normal. I used to have a link to someones site that detailed a repair of the piston. It involved using RTV. I think the last time I tried visiting the site it was down. I usually repair things like this as well but I didn't feel like messing with it. So I just bought new ones and now my headlights really work great.
1. Carefully disassemble the relay by prying up the retaining ring all the way around.
2. Pull the plunger/bladder assembly out of the plastic port housing.
3. Get two little o-rings and put them around either end of the rubber "dumbell" shaped diverter that's at the end of the shaft attached to the bladder. It might take a few tries with different sizes, but get ones that offer just the tiniest bit of resistance with the port housing once "installed" on the rubber diverter.
4. Get a cotton swab, impregnate it with grease, and then use it to put a thin film of grease inside the port housing.
5. put a thin coat of RTV on the outer end of the diverter and slide it carefully into the port housing and let it set overnight
6. remove diverter from port housing and repeat steps 4 & 5 for the inner end of the diverter (you'll have to slide past the outer end this time, that's why we let it set up first)
7. pull diverter back out, regrease a little, reassemble
Note: You might be able to skip the RTV-ing part altogether if you feel you got a sufficient seal with just the o-ring and grease. I did not however, and the RTV got me damn near airtight. I'm going on 2 years with this repair.
Burning Brakes
Joined: Jun 2002
Posts: 837
Likes: 3
From: Texas
Here is a site with some pics.....once there click "headlight relay repair".
http://iotech.no/corvette/
You don't need to do all the steps in the procedure shown, but pics can be useful. I did almost exactly the same rebuild as the write-up in the above post. I believe the o-rings I used were 5/16" OD X 3/16" ID X 1/16" thick. The idea is to flare the cups at each end of the rubber piston with the o-rings. Stick them there with RTV or 3M weatherstrip adhesive. Mine have held for 2 years now.
http://iotech.no/corvette/
You don't need to do all the steps in the procedure shown, but pics can be useful. I did almost exactly the same rebuild as the write-up in the above post. I believe the o-rings I used were 5/16" OD X 3/16" ID X 1/16" thick. The idea is to flare the cups at each end of the rubber piston with the o-rings. Stick them there with RTV or 3M weatherstrip adhesive. Mine have held for 2 years now.
Thread Starter
Team Owner
Joined: Jun 2004
Posts: 20,216
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From: Smile, it's just the internet.
Thanks for the help, guys! I fixed both my relays at a cost of $0.76. I couldn't be happier! I blasted them and painted them prior to reassembly. I used a specialized vacuum grease to seal up the diaphragm and o-rings. We use lot's of vacuum equipment here at work, so I borrowed a little. Anyway, they now hold a 25+ vacuum with no leakdown.
One question...
Jus how fast os the wiper door supposed to close? Mine is almost violent with the force it uses to pull closed. Perhaps, I just applied too much vacuum?
One question...
Jus how fast os the wiper door supposed to close? Mine is almost violent with the force it uses to pull closed. Perhaps, I just applied too much vacuum?
Team Owner
Joined: Mar 2002
Posts: 24,160
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Originally Posted by CGGorman
I used a specialized vacuum grease to seal up the diaphragm and o-rings. We use lot's of vacuum equipment here at work, so I borrowed a little.
Jus how fast os the wiper door supposed to close? Mine is almost violent with the force it uses to pull closed. Perhaps, I just applied too much vacuum?
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Burning Brakes
Joined: Aug 2004
Posts: 914
Likes: 0
From: Longview Texas
wonderful
glad you got them fixed, vacuum grease does sound good though ...... hmmm....... any I used this site referred to thruogh this forum ... here look to the left and there is a vacuum troubleshooting section ....... a quick ???? , I used brake fluid to enlarge my piston 
was that wrong? it works now though . Robert 
was that wrong? it works now though . Robert
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Vacuum grease? That sounds promising. Where would get ahold of "vacuum grease".
I use this stuff... Dow Corning High Vacuum Grease-
"A Silicone Lubricant For Glass Stopcocks, Joints, And Glass-Rubber Connections. Resists Most Chemicals, Heat Stable, Inert."
Scientific supply houses carry it. Probably any silicone based grease will do though... easy to find stuff..... Radio Shack... for CPU mounting (heat sink grease) I believe is silicone based.
You're not supposed to use any petroleum based products on the relays because petroleum will mess up the plastic & rubber parts.
I use this stuff... Dow Corning High Vacuum Grease-
"A Silicone Lubricant For Glass Stopcocks, Joints, And Glass-Rubber Connections. Resists Most Chemicals, Heat Stable, Inert."
Scientific supply houses carry it. Probably any silicone based grease will do though... easy to find stuff..... Radio Shack... for CPU mounting (heat sink grease) I believe is silicone based.
You're not supposed to use any petroleum based products on the relays because petroleum will mess up the plastic & rubber parts.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Originally Posted by CGGorman
Jus how fast os the wiper door supposed to close? Mine is almost violent with the force it uses to pull closed. Perhaps, I just applied too much vacuum?
Hans
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
One form of grease... don't know if this particular one is good for the relays though... dielectric type...
http://products3.3m.com/catalog/us/e...er/output_html
http://products3.3m.com/catalog/us/e...er/output_html
Racer
Joined: Jan 2006
Posts: 323
Likes: 4
From: McKinney Texas
To update this post, I just rebuilt my vacuum relays, using 11/32 O-rings.
Tips I found useful:
1)I bought the cheap vacuum pump from Harbor Freight, as it is hard to hear vacuum leaks when the engine running, and I do not like the idea of pulling vacuum from another car parked outside.
2) Rubber restore was not available, and soaking the pistons in brake fluid for 24 hours did not work for me.
3) Putting the O-ring "inside" the piston end, then holding it in place with a washer worked (see bottom end of piston in picture), but it takes up too much space to do both ends.
4) Cutting a groove in the piston where there already is a bit of a groove, and rolling the O-ring into it, worked great (see top of piston in picture), and it is easy to do both ends. This is what I finally decided on, and the valves work great. I used Vaseline to grease the bores.
5) I used a mig-welder to put the retaining ring back in place, but the suggestion of using a hose clamp is probably better.
Hope this helps.
Tips I found useful:
1)I bought the cheap vacuum pump from Harbor Freight, as it is hard to hear vacuum leaks when the engine running, and I do not like the idea of pulling vacuum from another car parked outside.
2) Rubber restore was not available, and soaking the pistons in brake fluid for 24 hours did not work for me.
3) Putting the O-ring "inside" the piston end, then holding it in place with a washer worked (see bottom end of piston in picture), but it takes up too much space to do both ends.
4) Cutting a groove in the piston where there already is a bit of a groove, and rolling the O-ring into it, worked great (see top of piston in picture), and it is easy to do both ends. This is what I finally decided on, and the valves work great. I used Vaseline to grease the bores.
5) I used a mig-welder to put the retaining ring back in place, but the suggestion of using a hose clamp is probably better.
Hope this helps.
