I’m in the process of getting ready to install the new tank into my ‘71 and have been doing a little research on the fuel separator valves available through the vendors and see a lot of negative feedback. Are the valves still failing at a fairly high rate? I saw a thread where the member had blocked off the vent lines and installed a vented gas cap. I believe a Stant 10853 cap was recommended. Is that a viable option?

Thanks in advance.

Allan

 

Hi Alan,
As far as I'm concerned these reproduction valves are still causing issues by leaking over time. I have had a third valve start leaking recently as a matter of fact. This most recent valve was purchased from Corvette Central about 4 years ago and was working fine until a few weeks ago. I was planning on taking my '73 on an extended road trip so I wanted to fill the tank as much as I could. (I know there a guys who say "Just don't fill the tank up so high!". But I feel you should be able to fill your tank so the gauge reads full not 3/4's full.... JMO......... Within a couple days I started to smell the fumes in my garage. Took a look underneath and low and behold the valve was leaking around the bottom seam and dropping on top of the spare tire plastic top as well as on the muffler. Ugh!!!! Not again, I said to myself!. What a pain these are to change out. I've mentioned this before in an article that I believe if you can find a good used original you are better off in the long run. I'll get into that more in a moment. This time when I removed the valve it was not only leaking but it had collapsed on the side, which renders the valve (ball inside) useless. Like you, I've researched and found that many are starting to just bi-pass the EVAP canister and get a "vented" gas cap. I decided that even though I'm pretty much a stickler for originality and wanting things to work as they should on my car I decided to go this route to try and see what happens. So I ordered a 68-69 Vented Cap from Corvette America (Now Top Flight). All I did was disconnected the lower hose from the valve which comes down from the tank. Plugged it with a bolt and clamped it tightly Left everything else in the EVAP system connected as original. I've been running the car for a few weeks now and so far I haven't had any issues.. No fumes in the garage either, and no leaks... If I ever decide to have the car judged again I can just reconnect and re-install the sealed gas cap. Something else, while I was waiting for the new cap to come in the mail I had another repro valve that I removed a few years ago. I decided to try to seal up the leaking seam with JB Weld's Marine Epoxy. I installed it on the car and ran it for a couple weeks even after I refilled the tank. It held up without leaking. So maybe this could be a fix but I don't know how long it would last over longer periods of time. Just a thought.
Finally, I've started to study the valves a bit more closely and I found that the original valves all seem to have extra sealant added rather sloppily to the bottom seams of the valve as well as a three digit number engraved by hand in them. Why the numbers? Inspection numbers? Perhaps.....day of the year? Perhaps. vs. the repro valves that do not have any added sealant along the bottom edges and no numbers engraved. Probably more than you or anyone else wanted to know, but pretty interesting.....If I were you, I'd still install the valve on your tank before installing it, and just block off the EVAP cannister and use the vented cap. But at least you'll have everything in place for a later date if you decide to hook things up.. I've included photos below to show a couple leaking valves, the collapsed valve and a couple originals showing the extra sealant and engraved numbers... Good luck with whatever you decide.
Tooch

Leaking bottom seam on a repro valve.

Collapsed repro valve.

Original valve showing engraved numbers.

Side view of an original valve showing the added sealant.

Disconnected tank overflow hose with plug and clamp. Note the JB Weld heavily applied to the valve seam!

Vented Gas Cap

 

Thanks for the great info! Do you happen to know if the Stant 18503 Is a vented cap?

 

That cap # isn't listed on the Stant website, but the #10853 is listed as a vented cap suitable for my '71 vette!
The #10852 is a sealed cap.

Paul

 

Tooch,

Thanks for all the info and expressing your experience/results. I do have a some questions though...

In the photo above I see the plugged hose but I have to ask if you did anything to plug the nipple to the valve case or is it just left open. I'm not exactly sure how the valve operates, but I'd be concerned about leaving that open with "access" to the tank's interior.

Also, rather than using JB Marine Weld, could the valve case's exterior just be completely coated in something like GOOP's "Seal All" which is resistant to gas & oil?

Paul

 

If you don't already have the 71 tank- I'd look at the 69's that didn't come with the air/fuel separator.

Albeit I'm running fuel injection and I needed a real vent as I'm running a return system.


See pic of my tank -look in the lower left hand corner. Used fuel rated hose- clamps and sealed it up.

I would not leave the Chinese piece of plastic junk there- it will leak- and if ever the unfortunate happened - accident or rolled over the car-gas could be pouring out.

Here is a GREAT article on the importance of tank venting-

https://www.streetmusclemag.com/feat...-tank-venting/

 

If you still have the valve on your old tank, it's worth a function check. I was pleasantly surprised that my '72's original valve still worked fine.

BTW, for Stant gas caps, Rock Auto carries them at 1/3-1/2 of the price of the Corvette-specific retailers. My replacement looks perfect.

 

Oops. That’s what I meant. lol

Thanks.