Vented fuel cap in cab?


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Yard Art
Yard Art

Posts: 92

Joined: Wed Nov 28, 2018 4:10 pm

Location: Bay Area, California

Post Wed Jul 22, 2020 2:16 pm

Vented fuel cap in cab?

I run into the strangest things working on my 1936 C-40 truck. After running the truck for a bit I opened the fuel cap to check the fuel level (gauge not currently connected), and got a bit of a "sssst" when I removed the cap. It doesn't look like the cap has a vent at all. Anyhow, I started checking the old IHC parts book for this truck, and found that the interior under seat tank came with either a non-vented cap with a "vented drain plug" or a vented cap with a non-vented plug. Somehow mine ended up neither the drain plug or the cap vented (I assume the cap was probably replaced with the wrong type). Note that on this series truck the fuel cap is inside the cab. It doesn't seem like a great idea to vent the tank into the interior with a vented cap. It should work fine, but it seems like it would stink up the interior if it was parked in the sun for long. Anyhow, I was just curious what others have in a truck with a interior mounted gas tank like this? If using a vented cap, does it stink up the interior?

Thanks,
Randy
1936 International C40
1962 Triumph TR4
2002 Chevy Avalanche

Golden Jubilee
Golden Jubilee

Posts: 8937

Joined: Thu Dec 27, 2012 12:45 pm

Location: Canada's left Coast

Post Wed Jul 22, 2020 4:32 pm

Re: Vented fuel cap in cab?

Try these guys for a better idea. I agree with you on the danger of having a fuel tank vent in the cab. In the past I have used one of those humidifier waterline taps into the filler neck. I ran a piece of fuel resistant hose to an inline fuel filter hidden behind a running board. The filter was there to keep out dirt and bugs.
I drilled into the filler neck, close to the top then threaded for an 1/8" pipe tap. I suppose this could be done to the top of a tank.
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Yard Art
Yard Art

Posts: 92

Joined: Wed Nov 28, 2018 4:10 pm

Location: Bay Area, California

Post Wed Jul 22, 2020 4:55 pm

Re: Vented fuel cap in cab?

Thanks, that does give me another idea to think about. My bottom of my fuel tank has two fittings. One goes to the fuel pump, the other is plugged. I was thinking I might use the second fitting to put a tube in for a vent, but your idea does give me another option. I am also considering adding a fitting to the fuel gauge sender. That might be easier since I could remove the sender and work on it out of the truck. Not sure if I have enough clearance there under the seat, though.
1936 International C40
1962 Triumph TR4
2002 Chevy Avalanche

Golden Jubilee
Golden Jubilee

Posts: 8937

Joined: Thu Dec 27, 2012 12:45 pm

Location: Canada's left Coast

Post Wed Jul 22, 2020 5:01 pm

Re: Vented fuel cap in cab?

The tank vent should be at the top of the tank or in the fuel filler neck. Safety first then keep it original.
I would rather have tools I do not need than to need tools I do not have
Thinking risks being controversial and possibly being offensive
User avatar

Yard Art
Yard Art

Posts: 92

Joined: Wed Nov 28, 2018 4:10 pm

Location: Bay Area, California

Post Wed Jul 22, 2020 7:43 pm

Re: Vented fuel cap in cab?

Good Point.
1936 International C40
1962 Triumph TR4
2002 Chevy Avalanche

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