"Rollover valve" on or near '67 gas tank? Is there such a part?
03-11-2014, 03:29 AM
#1
Melting Slicks
Thread Starter
"Rollover valve" on or near '67 gas tank? Is there such a part?
My '67 surprised (maybe "appalled me" is a better way to put it) by leaking fuel at the rear when I had it out on some errands on Sunday. The last time this happened, about 26 years ago, the tank had rusted out and was replaced. When I checked the car into the shop on Monday morning, the shop owner, a Corvette specialist, suggested that the problem might be, rather than failure of the fuel line or the replacement tank, a failed "rollover valve" which he said is a plastic part. Plastic or not, IS THERE SUCH A PART on a '67? Even if known by some other name?
I understand what the purpose of such a thing would be. It seems like something all cars should have had since about two minutes after cars powered by combustible liquids were invented, but I can't find any mention of such a part for a C2, not even in the very detailed drawings in Long Island Corvette Supply's catalog. Nor anything sounding remotely like that. I did a web search and found an eBay mention of a gas tank rollover valve for '70 through '74, but no earlier model year mentions (anywhere, not just eBay) of a rollover valve.
I'm not trying to play "gotcha" with the shop owner. If he's thinking of something that doesn't apply to my model year while we're discussing it without eyes or hands on the car, that doesn't worry me. I have only one model year to worry about, not sixty different ones as he does. I'm sure his guys will find and fix the problem. I'm just curious while I await the verdict. If it is tank failure, the replaced outlasted the original by about 30%. If it's rusted out, I'm thinking about stainless this time.
I understand what the purpose of such a thing would be. It seems like something all cars should have had since about two minutes after cars powered by combustible liquids were invented, but I can't find any mention of such a part for a C2, not even in the very detailed drawings in Long Island Corvette Supply's catalog. Nor anything sounding remotely like that. I did a web search and found an eBay mention of a gas tank rollover valve for '70 through '74, but no earlier model year mentions (anywhere, not just eBay) of a rollover valve.
I'm not trying to play "gotcha" with the shop owner. If he's thinking of something that doesn't apply to my model year while we're discussing it without eyes or hands on the car, that doesn't worry me. I have only one model year to worry about, not sixty different ones as he does. I'm sure his guys will find and fix the problem. I'm just curious while I await the verdict. If it is tank failure, the replaced outlasted the original by about 30%. If it's rusted out, I'm thinking about stainless this time.
Last edited by SI67; 03-11-2014 at 03:31 AM.
03-11-2014, 07:37 AM
#2
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No such thing on a mid year
03-11-2014, 07:48 AM
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There is a "rollover" valve built into the gas tank cap vent that seals the vent off in the event of going upside down.
I don't know how effective it is as I've never put one in the ditch!
Since it's made to work upside down, and your car is leaking while on four wheels, I wouldn't think that would be your problem.
I don't know how effective it is as I've never put one in the ditch!
Since it's made to work upside down, and your car is leaking while on four wheels, I wouldn't think that would be your problem.
03-11-2014, 08:38 AM
#5
Melting Slicks
Some heavy trucks have them on their fuel tanks to prevent fuel loss when the wheels are flapping like an upside down turtle.
All it is, is a fitting on top of the tank with a ball inside of an open ended tube that seals the vent opening when on its side or upside down.
All it is, is a fitting on top of the tank with a ball inside of an open ended tube that seals the vent opening when on its side or upside down.
03-11-2014, 02:33 PM
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The "rollover valve" didn't appear on Corvettes until the C3 era ('71 or '72, I think). 
03-11-2014, 07:22 PM
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The '63 caps (or some of them) did not have a two way valve in them to both vent pressure and vent vacuum. They just had a clear hole. The later caps would vent both ways but if you turned the cap upside down (which would simulate a rollover) you could not aply oral pressure and blow the vent open.
Whether it would constitute a true "rollover valve", I have no idea.
As a guess, the "rollover valve" started with the carbon cannister. Don't know though.
Last edited by MikeM; 03-12-2014 at 03:42 PM.
03-11-2014, 09:20 PM
#10
Drifting
The 26 year old rubber 3/8 fuel line connecting your tank to the steel fuel line is a good and simple place to start.
No such valve on a 67 fuel tank. I replaced the tank in my 67 and that valve doesn't exist on a 67. Only an overflow nipple at the fuel neck and the sending unit...that's it.
However, the 73 I used to own had a valve on the tank that was an evaporation/emissions-related part. Matter of fact that valve was leaking on my 73 but so was the tank and the rubber lines (disaster waiting to happen).
Oh, another possible cause could be the rubber gasket that seals the sending unit to the tank.
I don't know what a stainless tank costs, but a regular repro tank is $200 and if the one you have lasted 26 years, a repro tank is probably all you need.
In all, this is a simple issue to fix and it shouldn't cost an arm and a leg.
Frank
No such valve on a 67 fuel tank. I replaced the tank in my 67 and that valve doesn't exist on a 67. Only an overflow nipple at the fuel neck and the sending unit...that's it.
However, the 73 I used to own had a valve on the tank that was an evaporation/emissions-related part. Matter of fact that valve was leaking on my 73 but so was the tank and the rubber lines (disaster waiting to happen).
Oh, another possible cause could be the rubber gasket that seals the sending unit to the tank.
I don't know what a stainless tank costs, but a regular repro tank is $200 and if the one you have lasted 26 years, a repro tank is probably all you need.
In all, this is a simple issue to fix and it shouldn't cost an arm and a leg.
Frank
03-12-2014, 12:32 PM
#11
Race Director
There is a "rollover" valve built into the gas tank cap vent that seals the vent off in the event of going upside down.
I don't know how effective it is as I've never put one in the ditch!
Since it's made to work upside down, and your car is leaking while on four wheels, I wouldn't think that would be your problem.
I don't know how effective it is as I've never put one in the ditch!
Since it's made to work upside down, and your car is leaking while on four wheels, I wouldn't think that would be your problem.
I have put a few cars in the ditch over the years, but (thankfully) not my Corvette.
Larry
03-12-2014, 12:35 PM
#12
Race Director
The 26 year old rubber 3/8 fuel line connecting your tank to the steel fuel line is a good and simple place to start.
No such valve on a 67 fuel tank. I replaced the tank in my 67 and that valve doesn't exist on a 67. Only an overflow nipple at the fuel neck and the sending unit...that's it.
However, the 73 I used to own had a valve on the tank that was an evaporation/emissions-related part. Matter of fact that valve was leaking on my 73 but so was the tank and the rubber lines (disaster waiting to happen).
Oh, another possible cause could be the rubber gasket that seals the sending unit to the tank.
I don't know what a stainless tank costs, but a regular repro tank is $200 and if the one you have lasted 26 years, a repro tank is probably all you need.
In all, this is a simple issue to fix and it shouldn't cost an arm and a leg.
Frank
No such valve on a 67 fuel tank. I replaced the tank in my 67 and that valve doesn't exist on a 67. Only an overflow nipple at the fuel neck and the sending unit...that's it.
However, the 73 I used to own had a valve on the tank that was an evaporation/emissions-related part. Matter of fact that valve was leaking on my 73 but so was the tank and the rubber lines (disaster waiting to happen).
Oh, another possible cause could be the rubber gasket that seals the sending unit to the tank.
I don't know what a stainless tank costs, but a regular repro tank is $200 and if the one you have lasted 26 years, a repro tank is probably all you need.
In all, this is a simple issue to fix and it shouldn't cost an arm and a leg.
Frank
Another possible leak source is at the two main electrical connections on the gas tank sending unit. On original sending units, the packing nuts can be tightened. On repros, this possibility is 50/50.Get under the tank with a flashlight and check it out yourself.
Larry
03-12-2014, 01:25 PM
#13
Race Director
