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fuel tank leak-discouraged

D

dennis

Member
I have not wanted to touch my rv for a good week now. I found not one, but two leaks after spending a good 2 weeks in proseal and rivets. I have the tank sitting there and can't bring myself to test it again. i prosealed the baffle from the outside where it meets the skin. Will this work or do i have to cut a hole in the baffle to proseal from the inside? Oh bye the way, i already fixed the first leak where the outside rib meets the rear baffle.
dennis
 
my money

is on you will have to do it from the inside. if not the fuel will be trapped in between the rivets and leak from the rivets.
 
Been there.

Sealing from the outside is not good. It may work for a while, but do you really want the trouble of taking it off your flying RV to fix later?

Prior to painting, I leak tested my tanks with mogas and there was a leak. Yes, it was discouraging. I cut an access hole in the outboard rib and sealed the leak from the inside, then sealed and pop riveted a patch over the opening using those tank rivets Vans sells.

As most things go, the thought of opening up the tank again is much worse than actually doing it. Get it done now and you'll be better off.
 
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Depends where the leak is. I would clean the leaking area up and pro-seal it up well. Let the seal cure for a a good long time. It will seal it up with no problems. It is done often on commercial aircraft.
 
both-

the guys here have done both.

Sealing from the outside is easier but is more likely to leak in the future. One Rv'er says the idea of taking the tanks off is worse than actually patching the leak.

Consider- a large hole saw bit will make short work of access and a larger hole saw (without the pilot bit on a drill press) makes a perfect patch (3" min- 4" patch)
 
Dennis.
on the baffle - skin leak, drill out the rivets along the leak then work in some slightly thinned proseal with a feeler gauge and little vacuum applied to the tank. you will see the Proseal slowly suck into the tank, then rivet. Its easy.
 
FrankK90989 said:
Dennis.
on the baffle - skin leak, drill out the rivets along the leak then work in some slightly thinned proseal with a feeler gauge and little vacuum applied to the tank. you will see the Proseal slowly suck into the tank, then rivet. Its easy.
Click to expand...

This is a good suggestion, but be careful about how much vacuum you put on the tank. I had a similar problem and I was cautioned that it doesn't take much pressure to damage the tank. Also if you have had fuel in the tank previously, there are some other cautions that you need to take. Talk to someone who has done this. I had some expert help with mine.
 
Tell me it isn't so...

Sunday I noticed some blue staining around one of the top rivets on my left tank. I suspect I have a very small leak there and contacted Van's to see what they recommended after searching the VAF archives.

Here was their response:
Van's said:
ry these in the following order, eventually one will work

1. Try Loctite 290. This is a thin threadlocker that will wick around the rivet head. Some try applying a small vacuum to the tank to help suck it in. Be careful not to collapse the tank.

2. Squeegee tank sealant around the rivet head - many will skip this as they don't want black blob on their paint

3. Remove tank, cut access hole in rear baffle, add sealant over offending rivet and anywhere else that looks suspect, rivet plate over hole using blind rivets and more sealant
Click to expand...
Since my plane is not painted, all of these are possible but I thought I would try option 1 and see how it works. Do any of you have a suggestion on how to put a small vacuum on the tank?
 
N941WR said:
Do any of you have a suggestion on how to put a small vacuum on the tank?
Click to expand...
Hand vacuum pump, available from any auto parts store, Sears etc. Connect it via 3/16 plastic tube to the fuel vent line and tape over the fuel cap. You can control the vacuum much more precisely than using a shop vac, and you don't have to worry about blowing the thing up if you have gas vapors in the tank.
 
I don't know where the leak is, but I was lucky (VERY lucky) when mine leaked on the outboard end. I was able to fix it through the gas cap. With either the inboard end (float gauge) or outboard end (gas cap) you shouldn't have to cut. I made a tool to spread the proseal inside and it worked fine.

Bob Kelly
 
videobobk said:
.... I made a tool to spread the proseal inside and it worked fine.

Bob Kelly
Click to expand...

Bob-

For us non-imaginative toolmaking types....could you post a pic? I too have a leak on the outboard end at the rib/baffle. In hindsight, I fretted too much about what the instructions say about putting a thin layer of sealant on the rib flanges prior installing the baffle. I later determined my small bead of sealant on the the end rib was too far down, and it "rolled" instead of "squished" when I set the baffle in place. Sorry for all the technical terms...

I thought about having my 5 year old son reach up through the gas cap hole and smear some pro seal around, but got scared when I envisioned having to explain it to Mom...
 
Tool

Since that tool had only one use, I don't think it exists anymore. It was pretty simple, and based on the size of a fingertip. I took an aluminum wire, probably about 1/8" diameter that was fairly stiff but very bendable and put a small ball on the end of it. I turned an aluminum ball on a lathe, but you could use anything about 1/2" in diameter.

I shot the proseal through a syringe with a tube on the end to get it sort of in place, then took the tool and pressed/slid the tool over the bead. Not the neatest operation in the world, but it did the trick. I did clean the area with MEK first. A small mirror and LED light inside helped with inspection. The hard part was waiting for the proseal to harden to see if it worked!

Bob
 
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