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Interesting Sealants

Flyrod

Well Known Member
I recently pulled my left tank to fix a growing leak. This tank has an aerobatic flop tube, so the sender unit is mounted on the aft bulkhead of the tank. I thought the sender would be the leak source and it appears this is the case. Does anybody have a clue which sealants were used here? The black sealant around the sender is hard, but the gray sealant on the seams ranges from semi hard in the upper portions that are rarely exposed to fuel to very soft and easily moved with your finger in lower areas that are always exposed to fuel. The gray sealant is a darker gray than the recent ProSeal that was used on the access cover. The ProSeal on the access cover is hard.

The tanks are 11 years old with about 850 hours. The grey sealant appears to be holding despite its very pliable nature. The black sealant around the sender appears to be the problem. Has anybody seen this before or have a clue what the year 1999 sealants might be? :confused: I plan to have the sender opened, cleaned of sealant and ProSealed without gaskets.

Tank%20Leak.jpg
 
I have no idea what that goo on the sender is.

The grey sealer on the "z" brackets appears to be ProSeal as does the sealer on the access cover. ProSeal is never "hard" and the color as well as the stiffness of ProSeal depends on the mix ratio used. At least that's my experience.

Larry
 
Tank repair done!

Sealed.jpg


Van's Proseal in a tube was used. Never really found out what the old stuff was, but it didn't last seven years. It was all cleaned up and gaskets removed. plates were put back without gaskets and Prosealed. The sealent Vans sells in a tube is pretty slick. It takes a little effort to mix it, but it is not difficult. The tube will fit, just barely, in a standard chalking gun so you don't need to buy the special gun.

The tank was tested with air and soap using the balloon method, then filled with fuel while sitting on the bench for a couple days. Passed all tests with flying colors then reinstalled.

While the tank was out, it was a perfect opportunity to check the suction side of the fuel system. 30lbs of air was connected to the tank suction line connection. this pressurized all suction piping, filter and tank switch valve. A soap test on all this revealed a small leak on a fitting near the fuel pump.
 
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