Al Downs Posted July 25, 2018 Report Share Posted July 25, 2018 Who has the secret to fixing leaking fuel caps? I have replace both the large and small o rings and tried adjusting several times but still they leak. Short of not filling the tanks so full I don't know what else to do. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 25, 2018 Report Share Posted July 25, 2018 Make sure the cap itself is leaking and not the ring of epoxy holding the filler / cap threads into the wing. It's a known issue that over time the epoxy degrades and fuel can seep through. The repair Roger Lee has suggested is to Dremel down a few millimeters into the epoxy (don't remove it all!) and lay in a new layer of epoxy to seal it back up. I'm sure he'll chime in shortly with details. Link to comment Share on other sites More sharing options...
Al Downs Posted July 25, 2018 Author Report Share Posted July 25, 2018 I checked several times and it is not the seal around the ring. This is happening on all 4 CTLS's we have and it is worse on some. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 25, 2018 Report Share Posted July 25, 2018 3 minutes ago, Al Downs said: I checked several times and it is not the seal around the ring. This is happening on all 4 CTLS's we have and it is worse on some. That's weird. Are the vent tubes clear? Also, do you fill the tanks all the way up? I have one gear leg that sits a little higher than the other, if I fill the tanks completely fuel *will* slosh out of the vent onto the top of my right wing. Oh, but you said CTLS, so you have wingtip vents. Link to comment Share on other sites More sharing options...
Al Downs Posted July 25, 2018 Author Report Share Posted July 25, 2018 My vents are in the wing tips. We sometimes do have the tanks pretty full but even then it shouldn't happen Link to comment Share on other sites More sharing options...
Anticept Posted July 25, 2018 Report Share Posted July 25, 2018 What makes you believe they are leaking? Not being condescending, but sometimes people misattribute fuel leaking to people being messy and spilling fuel. Link to comment Share on other sites More sharing options...
Tom Baker Posted July 26, 2018 Report Share Posted July 26, 2018 I went down the same road as you. I finally resealed around the filler neck and mine went away. The leak was from between the epoxy and the aluminum ring. It just looked like it was coming from the cap. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 26, 2018 Report Share Posted July 26, 2018 Hey Tom, what epoxy did you use to reseal? I know any epoxy would work, just wondering what others use. I have some light fuel streaking on my right wing that is probably the seals. Link to comment Share on other sites More sharing options...
Tom Baker Posted July 26, 2018 Report Share Posted July 26, 2018 Andy, I used a fuel resistant JB Weld. I used a scraper and pick to remove the softened and damages old epoxy. I then taped off the inner and outer diameter of where I wanted the sealant. Make sure to leave a tail for pulling the tape.I let the JB Weld blow into the groove. I pulled the tape when it started to set up, but before it had really cured. I thought it looked really nice when finished. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 26, 2018 Report Share Posted July 26, 2018 1 hour ago, Tom Baker said: Andy, I used a fuel resistant JB Weld. I used a scraper and pick to remove the softened and damages old epoxy. I then taped off the inner and outer diameter of where I wanted the sealant. Make sure to leave a tail for pulling the tape.I let the JB Weld blow into the groove. I pulled the tape when it started to set up, but before it had really cured. I thought it looked really nice when finished. That’s what I thought aboit using, but was afraid it might be too stiff and not flex enough. Good thing is it’s cheap and easy to replace... Link to comment Share on other sites More sharing options...
Roger Lee Posted July 27, 2018 Report Share Posted July 27, 2018 I use my Dremel tool with a small round tip bit. Go around the outside edge of the cap and down about 1/8". There is a small shelf like protrusion there. Then clean with lacquer thinner and pour the open gap around the cap with the epoxy or your JB weld.. The small round bit makes short work of the removal job. p.s. Most people think fuel around the cap is a leaking cap, but more times than not it's just the vent tube. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted July 27, 2018 Report Share Posted July 27, 2018 6 hours ago, Roger Lee said: Most people think fuel around the cap is a leaking cap, but more times than not it's just the vent tube. I will never forget one morning in Oregon flying with you and dozens of other CTs. As I looked across the group of airborne (mostly) CTSWs I was amazed at the rainbow that came each time one of them banked for a turn. 3 or 4 rainbows at once, continuous color as long as the group was there, backbit and maneuvering even gently. My point is with full fuel the whole fleet was venting away fuel at every little turn. Maybe the CTLS isn't as bad but I think its about flat tanks and sloppy turns. Since we can't see our noses there are a lot of sloppy turns with our adverse yaw prone planes. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 27, 2018 Report Share Posted July 27, 2018 That flight is exactly why I never put in more than 15 in each wing any more and I changed out my vent tubes. The new vent tubes never spewed fuel again after that trip. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 27, 2018 Report Share Posted July 27, 2018 11 minutes ago, Roger Lee said: That flight is exactly why I never put in more than 15 in each wing any more and I changed out my vent tubes. The new vent tubes never spewed fuel again after that trip. Is there a new design vent tube? Link to comment Share on other sites More sharing options...
WmInce Posted July 27, 2018 Report Share Posted July 27, 2018 54 minutes ago, Roger Lee said: The new vent tubes never spewed fuel again after that trip. Roger, any way you could post a link to those for us? Many of us are interested. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 27, 2018 Report Share Posted July 27, 2018 I did a research project back in late 2007 on the uneven flow on the wing tanks and changed out the vent tube to see if pressure had any affect. It didn't, but I never ever had any fuel come from the vent tube again in all my years. I originally only put these on for a test, but the side affect was no more vent tube leaks. So I kept them. You can buy some aluminum or stainless steel tubing from Ace Aviation. Then just bend it with a small handheld tubing bender. I then threaded the end so it would screw into the cap hole and use the nut to secure it. Worked very well all its life. They are about 5" tall. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 27, 2018 Report Share Posted July 27, 2018 Many airplanes with wing tanks have similar vents...I like it! The extra height might slve my issue of fuel sloshing out the vent when parked with full-ish tanks on uneven grass too. Link to comment Share on other sites More sharing options...
Tip Posted July 27, 2018 Report Share Posted July 27, 2018 If you cover the LS caps with bolus tape, it will blister where the gas is weeping. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 27, 2018 Report Share Posted July 27, 2018 Hi Andy, Yes these style vents have been around longer than both of us put together. They're inexpensive and easy to make. It only takes about 30 minutes. Cut the tubing, bend it and thread one end. Link to comment Share on other sites More sharing options...
Ben2k9 Posted July 27, 2018 Report Share Posted July 27, 2018 11 hours ago, Ed Cesnalis said: I will never forget one morning in Oregon flying with you and dozens of other CTs. As I looked across the group of airborne (mostly) CTSWs I was amazed at the rainbow that came each time one of them banked for a turn. 3 or 4 rainbows at once, continuous color as long as the group was there, backbit and maneuvering even gently. My point is with full fuel the whole fleet was venting away fuel at every little turn. Maybe the CTLS isn't as bad but I think its about flat tanks and sloppy turns. Since we can't see our noses there are a lot of sloppy turns with our adverse yaw prone planes. Does anyone know if the CTLS does this? Link to comment Share on other sites More sharing options...
Roger Lee Posted July 28, 2018 Report Share Posted July 28, 2018 The CTLS vents are out on the wing tips and higher than an SW. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted July 28, 2018 Report Share Posted July 28, 2018 7 hours ago, Roger Lee said: The CTLS vents are out on the wing tips and higher than an SW. Isn't the tip the worst place for sloshing? The root location would minimize while the wing tip location should amplify the amount of fuel lost. The additional height is easily negated at the wing tip. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 28, 2018 Report Share Posted July 28, 2018 Hard to slosh through all those feet of 1/4" tubing. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted July 28, 2018 Report Share Posted July 28, 2018 1 hour ago, Roger Lee said: Hard to slosh through all those feet of 1/4" tubing. that's short duration protection your right, should help on turns. Link to comment Share on other sites More sharing options...
Mike Koerner Posted August 4, 2018 Report Share Posted August 4, 2018 One disadvantage of the "Pitot" style vent is water induction in rain. The little bonnets on top of our fuel cap vents inhibit this as the air can make the sudden turn up and into the tank but water with its higher density, mass and inertia can't. Similarly, the Pitot vents will inhale more sand, bugs and dirt. Mike Koerner Link to comment Share on other sites More sharing options...
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