Aluminum gas tank filler neck repair

bchessell2

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Nov 23, 2015
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I have an aluminum fastback tank I got from walridge over 10 years ago.The fuel has been leaking from under the quick fill filler cap were it is fastened to the tank.There was some kind of brown filler they used to seal it when made .It has been flaking off now when I fill it anywere near the top it leaks out when it splashes. Anyone have this problem.Wondering if there was an epoxy sealant of some kind to spread inside were the other stuff was.
 
TBW said:
Araldite 2002 is worth a go . But also + 1 for JBWeld
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Both of these are epoxies, which have good adhesive properties and fuel resistance.

Best practice to epoxy bonding to alu, you need to abraid the area to create a roughness to help attachment. Also, fresh exposed alu surface will oxidize within moments of air exposure. Oxidized alu makes for a poorer bond. There are chemical treatments to help strip the oxide and keep it unoxdized while epoxy is setting, but a good alternative is to place a coating layer of epoxy onto the roughend surface, give it some further roughening using steel wool or course wire wheel at low speeds. Idea is you are exposing unoxidizedsurface already coated in epoxy, little or no oxidation can occur and bonding properties are maximized.
 
When you look inside were the filler cap is inserted they cut the main tank body and bent up the tabs.Looks like a dozen of them.They put a brown sealant of some kind to fill the area in.It has slowly eroded away. That is the area I am going to fill in.
Thanks Guys
 
concours said:
Welding is not an option with the OP's described scenario, the joint cannot be cleaned.
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Yes, but it isn't "welding" as such, more akin to brazing so it would only require a layer of HTS to 'bridge' the joint.
 
L.A.B. said:
I can't see why not. Have you used HTS or similar?
www.frost.co.uk

HTS-2000 Alloy Repair Welding Kit - Fluxless Aluminium Brazing Rod - Frost Auto Restoration Techniques

This second-generation rod gives a stronger join and is simpler to use. It also easily penetrates past impurities that lay below the metal's surface, which may be impossible to penetrate with previous rods
www.frost.co.uk www.frost.co.uk
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Yes I have.

The heat will make the remaining sealant boil up into the attempted weld joint.

I will fold my tent now.

46 years in the welding trade.

I have nothing further to add.

🫡
 
Ideally if the joint is only affixed with folded tabs and some type of bonding material, it might possible to unbending tabs and fully remove the neck with some heating to soften adhesive. This would allow thorough cleaning, surface prep.
But a suitable solution may be just a good clean up, prep and thickened epoxy product stuffed around the joint.
 
So use this to seal aircraft fuel tanks, double skin repairs etc.
Thiokol PR 1422B 1/2 or B2 . The number after the B indicates curing time.
2 part . Available via aviation suppliers. This will work. 👍

PR-1422 Class B Fuel Tank Sealant​


PR-1422 Class B is an aircraft integral fuel tank sealant. It has a service range from -65F (-54°C) to 250°F (121°C), with intermittent excursions up to 275°F (135°C). This material is designed for fillet sealing fuel tanks and other aircraft fuselage sealing applications. The cured sealant maintains excellent elastomeric properties after prolonged exposure to both jet fuel and aviation gas.

PR-1422 Class B is a two-part, dichromate cured poly-sulfide compound. The uncured material is a low sag, thixotropic paste suitable for application by extrusion gun or spatula. It cures at room temperature to form resilient sealant having excellent adhesion to common aircraft substrates.
 
Will it work with ethanol gasoline? Says OK with jet fuel and avgas.
 
I am only going to assume that Bruce has the same issue as i do . There are remnants of brown filler but most of it is long gone . The tank is roughly 12 years old and maybe from the same manufacturer . From the picture , it shows the area that needs to be sealed . There really is no way to bend down the tabs without really messing everything up . The question is ..What sealer / filler does one use ...... JB Weld , Seal All , Quick Steel Metal tank repair . It certainly won't take much to do the job
 

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It is the same as yours ron.Same time frame and same problem. It may have been time alone or the fuel itself that broke it down.I don't want to disturb the fuel filler cap tabs and really cause a problem .It looks like the brown filler just got aged and broke down.Hope to find out if another product might work.Probably some kind of sealant like jb weld. Everyone has had some great choices to try.
 
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