Paul71LT1

Does anyone know if leaky C3 vacuum relay valves can be rebuilt, or do they have to be tossed and replaced? My original '71's are getting a little leaky. I took each one out and bench tested it. The two head light units leak a "little" and the wiper door unit leaks more, but not enough to cause rough idling or affect function, it just flattens the vacuum tank within a couple minutes of parking the car. Leak is out the open vented end of the spool valve and since all the parts are plastic I know it's not corrosion, just seal wear. Generic replacements that I found are in the $65 range and GM Delco units as per original are almost twice that much. Since my car is very original I would have to spring for the more expensive pieces. I'd like to hear the thoughts of the C3 corvette masses regarding vacuum relay valves.

'75

, I'm interested in this too. Both mine for the headlights leak. I took them apart and the seals on the spool are worn. The diaphrams are good yet. I hate to put out another $100 for these, this car is putting me in the poor house fifty or a hundred at a time.

goinbroke

Good pic of the valve Dean (lower pic). There are "cups" at each end (not shown in the pic). Get 4 o-rings 5/16" OD X 3/16" ID X 1/16" thick. Swab some black 3M weatherstrip adhesive into a cup, then press an o-ring into it and keep some pressure on it until it sets up. The idea is to flare the cups on each end of the valve so that it makes contact with the inner cylinder of the relay. Mine have help up for over 6 years now using this method.
When I reassembled my relays I also put a very thin coat of RTV on the diaphram.
Hope this helps.

'75

Good idea, thanks. Do you think it will help to lube them with some petrolium jelly or similar when I put them together with the o-rings?

goinbroke

Yes, I used a Q-tip to reach up into the plastic body. Seems like petrolium jelly is what I used. Also a light coat on the outside of the rubber valve. I cut some new pieces of foam for the filters as one of mine was shot and the other missing. Be sure and bench test the relays with your hand held vacuum pump after reassembly.

Alan 71

AKTBIRD,
Great pictures! How did you get the 'spool' out? I thought you had to un-crimp the diaphragm end to get at it. Thanks!
Regards,
Alan

'75

There's a small washer looking clip on the bottom end, just pried it off with a small screwdriver, then put the small screwdriver into the ports and gently moved the spool out enough to get ahold of it. Don't know if that retainer piece will stay on later, I might have to crimp something else onto the metal rod.

'75

ENG40

Great thread!

Alan 71

Thanks Aktbird!
Regards,
Alan

Paul71LT1

Thank you all for your input. I too didn't think I could get the spool out without opening up the crimp on the diaphragm cup and since the diaphragm is still tight I really didn't want to go hacking on that! I will try the spool release trick and get a couple o-rings for the cups.

Goinbroke, how did you reassemble? and how did you get access to the diaphragm?

speedreed8

this website might help. goodluck

http://iotech.no/corvette/index.php?...d=10&Itemid=11

fotyfobravo

OK...this hurts me to say this, but I have sprayed the insides with WD40. It's a Bubba fix, but it causes the rubber to swell and it will once again control the direction of vacuum. Sorry to admit this! I feel so cheap! I am going to bed.

'75

Ok, got them fixed and working good, saved some$$$

'75

Thought I should verify, that's grease on the q-tip, not super glue

Paul71LT1

Great pics. How did you hold in the spool valve after putting it back? I haven't taken mine apart yet so I can't visualize how tough it will be to get apart and reassemble. Three day weekend coming so I hope to Git 'er done!

goinbroke

Paul, I took mine apart per the link posted by speedreed, but it looks like Dean may have come up with a much easier way. For furure reference I'll be anxious to see how he refastened the valve onto the shaft. It shouldn't take much to hold it in place. A very small C clip or even a dab of strong glue could work. From the factory I think they use some sort of stamp that flared a couple of "ears" on the shaft. In any case it saves uncrimpimg and recrimping the top housing. Nice job Dean....and great pics of the procedure.

'75

Thanks, The tiny washer in the pic with the pencil is what I pried off to get it apart. The rod has a flattened area near the end so I put the tiny washer on there and crimped it with needle nose pliers. I cycled the relay valves several times and it seems to be holding.

'75

Wow, over 2 years later and the relays are still popping the lights up together.

...Roger...

Cool thats nice to hear. I'm going to have to put o rings in a wiper door relay and see if it will add a little resistance to the valve action.