Removing JB Weld

I never should have bought this boat. (73 Valco 16x68) But now I have to deal with it. It's a leaker and so far I have found what looks like a bad seam in the keel, just under where a transom strut is. It's hard to tell exactly what is there due to clumps of what looks like JB Weld, or the like. Over and around that is some kind of material that looks like window glazing putty, but is much harder, and maybe roofing tar over that. I read that JB Weld can be removed by heating to about 600 degrees. I have a Mapp torch, but I'm wondering if I run the risk of weakening the aluminum, which has a melting point of not much more than that.

Once I get it off, I'm not sure what to do with it. Some of the rivets look like they have been re-peened because the heads are flattened. JB Weld again, done with the proper surface prep?

Your alloy is likely 5052-H32 and it anneals (softens) at 650-degrees F, while it's melting point is > 1100. You can buy a special 'TempilStik' marker that melts below the anneal temperature for $20 or so at a good industrial hardware place (e.g., Grainger Supply) or they say you can mark the tin with a Sharpie marker and REMOVE the heat before the marker begins to bubble.

Go slow ....

But yes, heat ... and patience will remove it. Or borrow a propane bottle with a propane nozzle, as that heat @ 3600 deg-F is somewhat lower than mapp gas @ >3,700; where butane is even lower @ 2,400, getting such a torch without gas for only $10 at Walmart and other places - see photo.

Oh, that alloy hardens again in air whilst cooling, so no worries getting it 'warm'. West Systems ~$22 kit of G-Flex 650 flexible epoxy would seal that forever ... once properly cleaned and primed of course. It must be painted to protect it from UV, like where gray Rust-Oleum paint works well.
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OK, upon further assessment, there is no seam there. The keel is one piece, riveted in place, as are the transom struts, so the leak has to be from the keel and strut rivets. Some have been bucked and a couple have that JB Weld-like stuff on them, which I think is harder than the aluminum. They all seem tight. There is also a lot of white flexible caulk.

So should I buck the rivets, and/or use G-Flex 650 to seal them? Best way to approach cleaning? Treat all the rivets with some kind of sealer? I'm thinking to scrape it and use an angle grinder or drill with a brush to finish and get into the crevices. Etch with vinegar before applying the G-Flex? Their site says to sand most metals, but doesn't mention aluminum. Your sage advice is appreciated!

A picture will help us advise.

This is my first try at loading a photo, hope it works out!

There is a rivet under all that grey stuff. The other end of the rivet is clear. It is rounded and has some dents in it. The rivet on the other side of the strut is also covered in this stuff.

Uncle Krusty said:

There is a rivet under all that grey stuff. The other end of the rivet is clear. It is rounded and has some dents in it. The rivet on the other side of the strut is also covered in this stuff.

Click to expand...

Photo worked .

If not leaking, there's one school of thought that says "If not broken ... don't fix it!" If it were mine and I didn't mind it from purely a cosmetic view AND the boat wasn't used in saltwater ... then I'd be inclined to leave well enough alone or maybe clean up the area some, and then just fix it whenever it became an issue.

I'm of the same mind, especially since it's a pretty ugly boat. But it does leak, quite a bit. There are probably other leaking rivets, I just haven't found them yet.

Do you think that might be a weld gone wrong? It's kind globular, like molten metal, but it's darker than the aluminum welds that are elsewhere on the boat. Could I just coat the whole thing with a mass of G-Flex, and the bottom side of the rivets as well?