Fuel System: gas cap and venting

[over50]

On my 1950 2R5, I was somewhat surprised to find the gas tank pressurized when I took off the cap to fill up. The weather is now hot. The cap I have seems to vent inward but not outward. Is that correct?

[warrlaw1]

It has to vent both ways. I had that problem and it sucked my tank in. On the side of the road I remembered StudeRich's advice and drove a spike through the middle of it. That vented it both ways and I haven't had a problem since. Good luck.

[Commander Eddie]

Hmmm. I'll just add to this thread. I just bought a new chrome gas cap for my 61 Champ. I did not think to ask if it vented. Are all gas caps made to vent? Should I check mine? Is there a way to tell by looking if it does, or does not vent?

[warrlaw1]

NO. The one I drove a spike through was "vented" according to the package. New ones are seldom vented both ways and that's why I "altered" mine.

[Skip Lackie]

Hmmm. I'll just add to this thread. I just bought a new chrome gas cap for my 61 Champ. I did not think to ask if it vented. Are all gas caps made to vent? Should I check mine? Is there a way to tell by looking if it does, or does not vent?

Modern gas caps are not vented outward, just inward, if at all. Studes need the old style that will breathe in both directions. If you look at the back side of the cap, you should see a small vent hole. Try blowing and sucking through it.

[StudeRich]

This Stant 10640 is vented and correct for Studebakers that have a Gas Door (Cover). Or 10491 Locking, press-on.

http://ww2.stant.com/modules/partLoc...m.cfm?id=10640
These are also sold as #11640 when "Carded".

_______________________________________________________________
This 10623 Gas Cap is for the exposed installations, i.e. Pickups, but will also work inside the Gas Door type Models.
However I have found that in tight areas like Avanti or '59-'61 Larks it is a bit difficult to turn them.

http://ww2.stant.com/modules/partLocator/view_diagram.cfm?id=10623

These are the ONLY correct OEM replacement Caps that are correct for our Cars, that I have ever bought.
They are sold under the Car Quest, NAPA, Gates, and Stant Carded, bubble pack #11623 (for 10623)

As you will see on their Website.

[over50]

Since my cap looked nice, figuring I really had nothing to loose, I drilled a 1/8" hole in the center check valve plate. Vents both ways now and looks the same on the outside. When I need a new one I will buy the correct part.
Thanks for the info.
Norm

[jimmijim8]

You nailed it- Hit the nail on the head

very good jimmijim

It has to vent both ways. I had that problem and it sucked my tank in. On the side of the road I remembered StudeRich's advice and drove a spike through the middle of it. That vented it both ways and I haven't had a problem since. Good luck.

[gmax336]

Has anyone retrofitted a modern non-vented evaporative control to a Studebaker? With a vented system, there will always be a loss of fumes into the storage area. Not a problem in a free standing garage. This could be a problem in an attached garage especially in warmer climates. This is one of the reasons attached garages were not permitted in some areas years ago.

Jerry

[Commander Eddie]

Okay. I checked the new chrome gas cap I just bought for my Champ truck and it appears to be vented. On the underside is a blue plastic piece with a hole in the center of it. I am not sure where it vents through, but it certainly looks like that is what it is designed to do. It has been hot here the last few days and I have had no problem with a vacuum forming in my gas tank so I believe the cap is doing it's job.
I constantly remind myself why this forum is so useful. These seemingly esoteric things up and you find yourself learning something you never even thought about. Keep the great questions coming. I'm a sponge.

[LeoH]

With the wagon, and it's near original fuel cap and rubber gasket, I'm sure I've got plenty of venting!

[over50]

Assuming there isn't gas on the cap, you can put the center hole up to your lips and try to blow and suck. You will then know whether it vents both ways, one way or not at all.

[warrlaw1]

Commander Eddie, the fuel pump will cause a non-vented cap to suck in the fuel tank. You won't notice it on the road until it runs out of gas. On mine, the bottom of the tank rose to the point the sender unit was showing fuel in the tank, but there was none. When I vented the cap and refueled, luckily the tank popped back out. It was a restored tank (Gas Tank Renu). An original might not pop back.

[Commander Eddie]

Commander Eddie, the fuel pump will cause a non-vented cap to suck in the fuel tank. You won't notice it on the road until it runs out of gas. On mine, the bottom of the tank rose to the point the sender unit was showing fuel in the tank, but there was none. When I vented the cap and refueled, luckily the tank popped back out. It was a restored tank (Gas Tank Renu). An original might not pop back.

Dave, I read post #12 from over50 about how to test the cap. I am going to try that and see what I can learn. If it turns out the cap is not vented then I will find one that is as quickly as I can. I certainly don't want to damage my fuel tank. I take it yours is not the original tank. I think mine is but it was cleaned out at some point during it's rolling restoration. Thanks for the valuable insight. Much appreciated.

[warrlaw1]

It's the original tank that has been coated and baked inside and out. Without the coating, the old metal would have been less able to return to its original form. Metal gets tired.