Each time I drained the tank and waited for spring to repair. The next spring no leak. Knock on wood, no leak so far this October.
.
Thanks CubPilot2!!! Mine are the Piper Vented Caps! and the 180hp one looks like the one my PA-18 friend described, what’s the significance of the 180hp on these caps? Do they also get used on other engines?
Typical with some 180 conversion STC’s
Evedently meant to ensure fuel flow with slight pressurization of system from ram air.
I dont buy that your fuel leak is “normal”. Keep checking. If it’s the caps, borrow your friends and test them or swap sides with your own. They should grip firmly with good gaskets.
Thanks CubPilot2!!! Mine are the Piper Vented Caps! and the 180hp one looks like the one my PA-18 friend described, what’s the significance of the 180hp on these caps? Do they also get used on other engines?
Typical with some 180 conversion STC’s
Evedently meant to ensure fuel flow with slight pressurization of system from ram air.
I dont buy that your fuel leak is “normal”. Keep checking. If it’s the caps, borrow your friends and test them or swap sides with your own. They should grip firmly with good gaskets.
The tank has been removed and repaired for leaks. When I confidence tested it myself before refitting with a couple of gallons of fuel by sloshing around all was fine, until I turned it upside down and fuel came out of the cap vent holes, as you’d probably expect!! The gaskets are new and fit securely.
Given the long thin design of the tanks, if they’re more than half full any kind of bank angle is going to get the fuel level moving towards the cap and if it gets to the caps, what’s to stop it dribbling out of the vents as it does when the tank’s inverted?
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A proper test for leaks would be to apply 3 psi of air pressure to the tank. Then brush soapy water over all of the seams looking for bubbles. Sloshing around as you did won't necessarily show pin hole leaks.When I confidence tested it myself before refitting with a couple of gallons of fuel by sloshing around all was fine, until I turned it upside down and fuel came out of the cap vent holes, as you’d probably expect!!
Philly,
Youre forgetting that while in flight, your engine should be running, thus imposing a (slight) negative pressure on the tanks, which is being relieved via the vented caps. Holding a tank upside down with fuel in it prior to installation is a somewhat meaningless excersize.
MTV
I have an 18 gallon left wing tank in my Cub and in my old Pa11. I have done 10,000 + slips and have never noticed any fuel leaking
Glenn
No flaps, every landing is at least one or more slips, sometimes in ground effect to slow down. No leaks on mine. My J4 front tank is vented and when in heavy turbulence it will splash gas on the windshield, worse as tank gets emptier
Glenn
Not if in a coordinated turnGiven the long thin design of the tanks, if they’re more than half full any kind of bank angle is going to get the fuel level moving towards the cap and if it gets to the caps, what’s to stop it dribbling out of the vents as it does when the tank’s inverted?
Not if in a coordinated turn
Can you you post a photo of your caps.
The vent hole described sounds a bit strange.
Is your J4 fuel cap as in the picture? and it splashes fuel out?
Great pic! That looks like the PA-12 underwing gauges in reverse!!
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Bingo, I coped and built from an original
Glenn