willysmjeeps.com

Hi all,
Are the gas caps suppose to "breath" at all? I am having a pressure problem on my 1952 M38A1. The vent tube on the tank is clear but pressure still builds up so much fuel leaks out of my pick up and sending unit fitting when she been driven for a long distance. Both gaskets are new and everything is tight. My gas cap has been painted over so many times over the last 50 years I can't tell if the round middle part is suppose to open or if it's just a bump. Plus the inside middle is pretty corroded. Time for a new cap? Any help will be appreciated, thanks guys.

Dragnet, I'm kinda new at this A1 stuff and can't really answer your question but I would like to know which of these caps would be correct for an early A1...

Mike,
If it has ribbing around the outer edge the one on the right is correct.

Gragnet,
Leave your cap loose and drive the jeep. Does the seepage stop?

It does have the ribbing, Wes. What is the cap one the left for?

The REO 2 1/2 T

http://www.g503.com/forums/viewtopic.php?t=101165

wesk wrote:Mike,
If it has ribbing around the outer edge the one on the right is correct.

Gragnet,
Leave your cap loose and drive the jeep. Does the seepage stop?

I will try it and let you know. It does stop after I loosen the cap when I stop driving her.

The non-vented cap that says "release slowly" on it will not and is not suppose to vent. So if pressure is building up in your tank then either the vent line to the air filter housing is plugged, the relief valve in the tank fuel pickup assembly is stuck or your fording valve is in the fording position.

1-Check the position of your fording valves.

2-Remove the vent line from the top of the tank. blow thru the line to the air cleaner. Is it clear? Remove the gas cap. Blow thru the tank vent line port to the tank. Can you hear air rushing into the tank?