Hey y’all! I have to weld up a thin aluminum catch can for a hot rod. I was wondering if y’all had any tips for keeping it cool? The tank is completely sealed and I’m welding a skull to it. The skull is cast and it’s gonna take some hear. Has anyone ever tried filling a tank like this with water? It’s either a great idea or the worst idea ever. Cheers!
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Heat up the cast skull with a torch to about 300° before you start to weld it.
This will help you get your puddle going much faster and keep the thin stuff from melting through. Just the skull if its real thick. If your not perficent in alum tig welding this is probably not a project to learn on… Just my two cents
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Here is the opinion of my business partner/ the welder.
“First off, tig weld it, dont try hitting it with a spool gun unless you want a mess on your hands. I would say to clean the areas on the casting he wants to stitch to the can really well, get everything fitting nice and tight in the locations he plans on putting welds, preheating the casting without putting a lot of heat into the can body until it comes time to weld. Get it fit, and weld it out. I would use 4943 filler as my go-to for it. 4043 works, too, but it’s not quite as strong, which isn’t a huge deal for this asthetic application. I would also recommend running some practice beads to get warmed up before getting into the actual project if he’s not super comfortable with tig welding aluminum. I like to put my tacks at the end of my stitches to help with hot short. Everything looks better when you plan your weld pattern and sequence. Or get someone else to do it that’s comfortable with that sort of thing.”
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I use 4943 tig rod for cast alum marine lower unit repair. Its hard to find but works awesome. 4043 is also a good choice for welding cast aluminum to 3000, 4000
series aluminum. Oh Tinwhisper beat me to it… The guys on top of things !!!
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@Bigdaddy2166 sorry I didn’t realize I got in between your posts.
I have just basic welding skills myself.
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No problem my brother…
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Don’t fill it with water… sure fire way to get cracks in the weld and base material. You will end up with a leaky tank. I agree with bigdaddy and Tin heat up the casting.
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So I got it all finished. A little preheat and beveled the edge of the casting a bit to make them more similar thickness. I also purged the tank to give the weld a bit of support in case I penetrated too much the tank handled the heat a lot better than I expected.
. I’m happy with how it turned out.
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Very nice…
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Well done indeed. With those skills I am surprised you had to ask on how best to do it…maybe you didn’t 
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djlois. I agree with you. Don’t think he needed help. Just reassurance 
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I have very little experience with aluminum, I had never welded a thin tank like that. I was worried it was just going to liquify the tank and fall out. Thanks for the help y’all!
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That looks great!! Turned out awesome!!
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