Gas leaking at gas cap

[72chief]

Ok, I know there have been many discussion about vented and unvented gas caps. The problem I'm having is when tank is over 3/4 full, gas spills out when turning. Purchased new cap at auto tire and parts, same thing. Any advice? This is on a 72 c10 original tank.

[Lattimer]

Originally Posted by 72chief

Ok, I know there have been many discussion about vented and unvented gas caps. The problem I'm having is when tank is over 3/4 full, gas spills out when turning. Purchased new cap at auto tire and parts, same thing. Any advice? This is on a 72 c10 original tank.

Pretty typical with these tanks. 72 should not be a vented cap, so you shouldn't have a leaky vent. That means its leaking around the cap gasket.

Check the condition of the filler neck. If its bent up, dinged, etc., it won't seal. Also if the inside area is bent out the cap will fit loose and not seal.

If all that is ok, could be the gasket on the cap isn't touching well enough. I used o-rings stuffed behind the gasket to make it push against the filler neck harder. I also put an o-ring around the center of the cap to help seal. So far its been leak free for 2 years.

Mine is a 70, so the cap is vented, it looks a bit different from what a 72 should look like.

[72chief]

Ok thanks, I can see where the o rings would help. I don't understand why a new cap didn't fix it, unless like you said, inside is bent out. The cap has never felt loose.

[Lattimer]

Originally Posted by 72chief

Ok thanks, I can see where the o rings would help. I don't understand why a new cap didn't fix it, unless like you said, inside is bent out. The cap has never felt loose.

Don't know. My tank is new, and I bought 3 caps to get 1 that didn't leak. after about a year that one started to leak.

[old Chevy guy]

The easy answer is don't fill it over three quarters. When I got my truck going recently after being apart for a few years the first fill up poured out the cap on every corner too. Bought a new cap at the zone . I wasn't overly impressed with the appearance but it doesn't leak. Mines a 71.

[72chief]

Originally Posted by old Chevy guy

The easy answer is don't fill it over three quarters. When I got my truck going recently after being apart for a few years the first fill up poured out the cap on every corner too. Bought a new cap at the zone . I wasn't overly impressed with the appearance but it doesn't leak. Mines a 71.

As thirsty as mine is, less stops at gas stations would be easier for me.