Self venting metal gas tank - can it stop venting with time ?

pecheux

Lieutenant Junior Grade
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Jun 9, 2006
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1,200
I own a 30 years old OMC self venting metal gas tank. Little usage, no rust inside, repainted it to make it look better ... etc

I beleve these tank vent from the cap, but there is no vent hole or vent screw. My question is: can it stop venting properly due to time ? There is always pressure in this tank when I open the cap.

Thank you
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
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Re: Self venting metal gas tank - can it stop venting with time ?

Assume a self venting tank should not hold pressure when cap is closed, should always be releasing pressure, used to have a plastic tank that inflated round as a pig so had to use it with cap slightly lose when operating the boat in sunny environments. Probably yours must have a very small hidden diaphragm somewhere inside cap that only releases bigger pressures.

Happy Boating
 

JimS123

Fleet Admiral
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Jul 27, 2007
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7,952
Re: Self venting metal gas tank - can it stop venting with time ?

Its just fine. Fogetaboutit. Think of it as a pressure relief valve. It'll open when it needs to but not before. Those tanks are the best ever invented. Never have to worry about vapors leaking out or moisture leaking in. One of mine is from the 1960's and still works fine. Just had to replace the gauge float because the E10 dissolved the lacquor, but that was only a buckandahalf fix.
 

Chris1956

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Mar 25, 2004
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Re: Self venting metal gas tank - can it stop venting with time ?

Didn't those old OMC tanks have a two position cap? Tighten it one click and the vent was open. Two clicks and the tank was sealed.
 

pecheux

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Re: Self venting metal gas tank - can it stop venting with time ?

Didn't those old OMC tanks have a two position cap? Tighten it one click and the vent was open. Two clicks and the tank was sealed.
I always used it fully closed, thinking this tank was safer to use than the ones with a vent hole in the cap. Epecialy when I have heavy cigarette smokers in boat using matches.
I'llcheck and see ... but how could it have worked fine for so many years with the cap fully closed if it had to be half open ?
 

JimS123

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Re: Self venting metal gas tank - can it stop venting with time ?

The "detent" in the cap (or half open if you prefer) is the pause point where you relieve any pressure. At tyhat point the cap is loose and will spill gas or take on water. Never keep the cap in that position.

If your crew are heavy smokers with matches, time to get some new friends. Your choice, but if you come in my boat you better not plan on smoking. (I was a smoker too so its not a prejudice).
 

pecheux

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Jun 9, 2006
Messages
1,200
Re: Self venting metal gas tank - can it stop venting with time ?

The "detent" in the cap (or half open if you prefer) is the pause point where you relieve any pressure. At tyhat point the cap is loose and will spill gas or take on water. Never keep the cap in that position.

If your crew are heavy smokers with matches, time to get some new friends. Your choice, but if you come in my boat you better not plan on smoking. (I was a smoker too so its not a prejudice).
That would confirm I was using it the right way then. Fully closed that is. I do have to say that sometimes when I open the cap halfway just to see how much pressure there is inside the tank, I am suprised at the rush of air that comes out of the tank.

As for smoking friends I have leaned out almost totaly. (ex smoker myself also) I do have to make an exception with one guy but he's my bro and I am tight with family ties. I have learned to let him hold the tiller so I sit up front without any smoke in my face. LOL
 

Prophammer

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Jul 2, 2010
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Re: Self venting metal gas tank - can it stop venting with time ?

just don't throw lit matches down in the bilge!
 
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