gas tank vent

The Era of The Square Body Racing Comets
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Groover
Posts: 1796
Joined: Wed Jun 02, 2010 11:36 pm
Location: Indianapolis, IN

Re: gas tank vent

Post by Groover »

Few years ago my 64 was making the "swoosh" sound when I opened the gas cap. I wasn't entirely sure whether it was pressure or vacuum. Then on our way to Pidgeon Forge on a very hot day after driving 200 miles, we stopped for gas. The tank was low on gas, maybe a quarter or less. I happened to have the trunk open before I opened the cap and I could SEE the floor of the trunk was bulged. When I opened the cap, the swoosh happened and I saw the spare tire drop as the tank top sucked back down to level.

So if you want to confirm whether its pressure or vacuum perhaps open the trunk and put your hand on the tank top while you open the cap. For me, with not that much gas in the tank and a hot day the pressure was enough to bulge the tank visibly. I took a pick and ran it around and under the gasket on the gas cap which apparently was dry rotted and blocking the vent? At any rate I haven't had the problem since.
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1964 Comet Caliente Convertible
30,000 miles on our rebuild

All Comets start out as dreams...

popscomet
Posts: 9689
Joined: Sat Jan 01, 2011 11:19 pm
Location: Jacksonville, Arkansas

Re: gas tank vent

Post by popscomet »

AS loose as my cap fits,,,it couldn't build pressure if you built a bon fire under it......good thing it has a door over it///been that way forever !! pop
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hotrodron
Posts: 29
Joined: Tue Jun 06, 2017 9:44 pm

Re: gas tank vent

Post by hotrodron »

thanks guys, I loosed the gas cap n ran fine, my initial trouble was the car would stall and not restart. took cap off (with a whoosh) could tell if it was vacuum or pressure. let car sit a couple minutes and it started right up. got a vented cap, no more troubles. Thanks again guys

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