View Full Version : Fuel tank vent

05-23-2008, 06:26 AM
Hi, new here, hope this is appropriate.
1960 Lark Station Wagon
I think the fuel tank is vented through the gas cap. At some time my brother replaced the gas cap with what I believe is a non-vented cap. Recently I dropped the fuel tank, used internal sealer, primed and painted the outside, and replaced the fuel sender gasket (which was positively leaking, probably for a long time). Car runs great!

???Now that I have fixed the air leak at the sender unit; have I made the wrong (maybe?) gas cap a problem and how serious is that? I think the worst it will do is starve the engine for fuel and make it stall.

Aside: I knew a mechanic at a new car dealership who showed me a gas tank that looked like a crushed beer can. Seems that model car had a problem with clogged fuel vent lines. Electric fuel pump would suck it flat.

???How far do I need to drive to get confidence I am OK?

41 Frank
05-23-2008, 08:21 AM
Why push the issue,;) just get a vented cap like all Studebakers have. Studebakers fuel systems never were designed for non-vented caps. You may experience fuel starvation. Most parts stores still stock vented caps.Cosmetically it won't be correct unless you order one from a Stude vendor.

Chucks Stude
05-23-2008, 09:10 AM
If you pressurize the fuel tank, you may risk blowing the diaphram in the fuel pump, it was not designed for pressure.

05-26-2008, 10:08 AM
Be sure that you get a vented cap! I had the wrong type on my Wagonaire and drove far enough one day to partially collapse the fuel tank as the gas got pumped out of it. The cap must have sealed really well that day, as it had been on there for years without any noticeable problem.

On the day the tank collapsed, I did notice that gas gauge kept going UP as I drove. The float must have been pushed up by the bottom of the tank. Eventually, the engine died because of fuel starvation.
Here's a photo of AFTER I had released the vacuum when I went to put more gas in the tank. I didn't get to see it in its more-collapsed state because I didn't know why the engine had stalled. I got a clue when I heard the air suck in as I took the cap off.
I was later able to drain out the gas, drop the tank, cap the inlet, fill it with water, and very carefully use the garden hose to pressurize it just enough to pop it back into a reasonable shape. DO NOT do this with air pressure as the tank can rupture. It only took about 3-5 psig of water to push the tank back out. I also had to bend the fuel pickup tube back into place.

[img=left]http://www.studegarage.com/images/gary_ash_m5_sm.jpg[/img=left] Gary Ash
Dartmouth, Mass.
'48 M5
'65 Wagonaire Commander
'63 Wagonaire Standard
web site at http://www.studegarage.com

05-26-2008, 10:29 AM
everyone's points are valid but one slight correction - 62-up Lark types did NOT use a vented gas cap. There was a vent tube connected to the filler neck that vented inside a body brace under the LR corner of the trunk floor. All other Studebakers that I've worked on (except maybe Avanti? I haven't looked) used a vented cap as I recall.


55 Commander Starlight

05-26-2008, 11:00 AM
Even station wagons, Nate? ;)

Matthew Burnette
Hazlehurst, GA

05-26-2008, 12:01 PM
I have no idea, never having worked on one... but pre-62 anything should have a vented cap anyhow so the distinction is unimportant to the OP.


55 Commander Starlight

05-26-2008, 03:31 PM
All Stationwagons use a vented cap, or the tank WILL collapse! :(

Studebakers Northwest
Ferndale, WA

06-08-2008, 11:49 PM
[8D]Thanks all, Great information.
I took a close look at the aftermarket gas cap and it is vented. I just got confused by the pressure warning printed on the cap. Vented caps do not build pressure, or vacuum (kind of the idea), but I guess they print that warning on all caps now regardless of whether it makes sense or not.