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Tank Cap Gaskets

BES

BES

Registered User
Esbjerg, Denmark
What do you use for tank cap gaskets for the Univair fuel tank caps? The ones supplied by Univair are made from butyl rubber so turn soft from auto gas fumes. I have tried to make my own using nitril rubber from a motorcycle inner tube. This works well, except for the fact that it blocked the tank vent on the last flight (thankfully only 25 min flight time). The tank was sucked in slightly, but there was an audible hiss when I removed the cap :oops:.

Does anyone have a good lead to cap gaskets made of silicone or nitril rubber?
 
I think the Atlee caps are mogas capable. That's what I have and haven't had any issues.
 
Thanks, but at Spruce's website, it says:
A variety of cap neck styles and materials accommodate oil, fuel, hydraulic or water applications. Accessory options let you build the filler assembly you need. Three different strainers (see Alternate Items) provide varying degrees of filtration for 300 Series caps and necks to help you maintain clean fluids within your engine system. Special mountings match the type of connections you require.

Not compatible with auto gas. :???:
 
Yes funny they say that because I've used them with auto gas for 3 years. I buy alcohol free auto gas though, are you burning street car gas with ethanol?
 
Yeah, I do. We cannot get car gas without ethanol in Denmark. I am running a two-year test of this 5% ethanol fuel in my PA-12 and my Champ (with the permission of our FAA) with a view to be able to allow all applicable E-AB aircraft in Denmark to use it. The price of 100LL is approx. $12.10 per gallon over here, versus $5.95 for auto gas.
 
You are right. I just need to make a punch which can cut the outer and inner in one fell swoop... :)
 
Use 1/8 or the same thickness of your existing gaskets Viton material available on ebay in small sheets. I replaced the old cracked gaskets on my -12 caps months ago and the auto fuel has had no affect on them.
 
It is weird, Steve. I bought a set of gas caps from Univair. The gaskets that were in them were OK for two years or so before they began to be a little cracked. The spare set of gaskets I bought at the same time became all gooey and soft in less than a week.
 
Mogas seems to change every year. My old plow truck was fine on ethanol for years, then it was fuel pump, accelerator pump and plastic float all at once. The caps and necks of my Scribner gas jugs sometimes have a loose fit, some times are so tight I have to switch them around to get them all on.(that's with E0). The tip of the drain valve on my gascolator drips for a day after sumping, and only last a couple of years. I doubt there will be a solution until the target stops moving. Can't wait for stable lead free gas.
 
Steve Pierce said:
I have never had an issue with the Univair gaskets.
Click to expand...

steve, I believe my my fuel caps are univair and in addition to the rubber gasket, there’s a plastic grommet under it that needs to be replaced. Do you know the part number of that piece?
Thanks
Foggy
 
Foggy said:
steve, I believe my my fuel caps are univair and in addition to the rubber gasket, there’s a plastic grommet under it that needs to be replaced. Do you know the part number of that piece?
Thanks
Foggy
Click to expand...

Cessna caps, at least some of them, had a thin plastic gasket that went under the rubber gasket. Never seen that on a Cub cap. Maybe someone thought tat was a good idea.

MTV
 
mvivion said:
Cessna caps, at least some of them, had a thin plastic gasket that went under the rubber gasket. Never seen that on a Cub cap. Maybe someone thought tat was a good idea.

MTV
Click to expand...
thanks gentlemen
It definitely could have been added by someone trying to help make it easier to open/close.
I’ll see how it works without the plastic.
Foggy
 
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