Fuel Cell leak

Tom McCutcheon · #1 01-11-2006, 07:53 PM

I thought I had just one leak in my left fuel cell (RV-4). However, after removing it and putting some fuel into the tank and then a slight pressure I found a leak where the prior owner had puttied the seam from the outside and another at the other end

. The one seam I can get from the inspection door

. But, the other seam I cannot get to from inside although I can see it from the fuel cap opening. Any suggestions on fixing these leaks

? Slosh - type of product etc. I will use the Pro Seal (Dyna Seal) from Van's for the areas I can get to, but I'm more concerned about the area I cannot reach.

Thanks in advance for your help

painless · #2 01-11-2006, 08:01 PM

Tom:

If you can't reach an area where you have a leak, consider cutting an access hole in your rear baffle, seal up the leaking area with proseal, and then pop rivet (with closed end rivets) and proseal a cover plate over your access hole.

Sloshing is not recommended due to the possibility of it peeling off and clogging your fuel system.

Regards,

Tom McCutcheon · #3 01-11-2006, 08:06 PM

Thanks Jeff! That is an excellent idea. The leak is at the end of the tank where the fuel cap is located. Very easy to cut an access hole and goup the leak as you suggested and then close it up again. Thank you - thank you.

Tom

painless · #4 01-11-2006, 08:18 PM

My pleasure Tom. Just make sure you use the same or heavier guage aluminum sheet for your access cover plate as is used for the rear baffle.

Regards,

aadamson · #5 01-11-2006, 08:19 PM

I've heard of people that use some kind of thinned down sealant, and then they draw a slight vacuum on the tank and suck the sealant back thru the effected area. Might be worth doing some research and trying before you cut metal... You can always do that if it doesn't work. Just be careful and it's doen's take much vacuum to misform items.

painless · #6 01-11-2006, 08:25 PM

Hey Tom.....just had another idea. You said that you can see the area that is leaking from your fuel cap? What about the possibility of taking a soldering flux brush, cutting the bristles in half to make them not so "floppy" and then fashioning some sort of extension so you can reach the area through the fuel cap? You could take aadamson's suggestion and thin down the proseal just a bit so it would flow more and see if it works.

Might be worth a try.......

Regards,

Tom McCutcheon · #7 01-12-2006, 04:19 AM

Jeff & Aadamson - all great ideas. This is such a great forum. I will try the brush (maybe extended brush - paste or tooth brush) idea first. Still, if I do have to cut a hole, it really won't be that much problem. I'm wondering if I should try to wire brush the areas for the new Pro Seal. The new Pro Seal dries grey. Whatever was used to build my tank was brushed on and is a dark red to black.

I had pro sealed the inspection door on a few months ago while it was on the plane and it hasn't leaked. Also, was fairly easy to take off. The Pro Seal pretty much stayed on the door and was easy to clean up with the wire brush on the grinder. It is pretty good stuff. When hardened it is somewhat like silicone in that it is very flexable. Probably why it works so good.

Anyone else doing this may want to mark the cover to make it easier to line up the holes when re-installing.

Tom McCutcheon · #8 01-12-2006, 07:45 AM

Jeff,

Forgot to ask you what you thin the Pro Seal with? I'm using the product from Van's that is a two part epoxy Dyna Seal. I got it in the tube form. I would have to squeeze some out and then thin it with ?? before applying it.
Thanks again Jeff.

Jamie · #9 01-12-2006, 08:42 AM

Some people have suggested fixing fuel tank leaks with a drinking straw. If you can reach the leaking area on the inside w/ the straw through the filler hole, you can thin down some sealant and (very carefully, of course) suck it up into the straw, then use the straw to apply a nice bead of selant along the faulty area.

alpinelakespilot2000 · #10 01-12-2006, 12:27 PM

Before you cut a hole in your tank, Van's recommends using self-wicking loctite (the green stuff) for small leaks. I used it on my one and only leak and it took care of it right away. It helps to hold a vacuum hose close to your fuel cap and then the loctite will be sucked right in. If the leak is not too big I suspect you'll see your problem solved. It "might" not be as permanent as cutting into your tank and using proseal, but it might last forever too, so it wouldn't hurt to try. Just another, less drastic option. Good luck.