I'm involved with aluminum welding 5 days a week. All our welding is pulsed MIG. I wouldn't even attempt to repair what the OP needs to be repaired, for anyone that wasn't a friend. It's a craps shoot with cast aluminum. If the OP is dead set on having it welded, then I would recommend that he finds someone to heliarc it. Each piece would need to be properly beveled, and possibly preheated depending on how hot it gets while grinding the bevels, before welding starts. There's an art to welding aluminum, that isn't required on steel.

Tig will be the only way but if it’s cast and sees any vibrations, good luck.

Look up belzona. We’ve put 480 disconnect handles on with this stuff repaired boats etc.. it can be sanded it’s bad stuff. Jb weld on steroids.

Belzona is good stuff for sure. Red hand, splash zone, etc. are good to go also but don’t hold up to vibration like belzona.

Hell Zip tie that thing with some heavy duty zip ties!! 😂😂

Aluminum is cleaned with acetone before welding, not a wire brush. I used to be really good at it but that was 30 years ago. You’re going to have to find someone who can tig weld it. MiG welding on aluminum is okay but not for fine parts. Aluminum rods for stick welding is a waste of money.

Cast aluminum is often too porous to be welded properly. Moltened together it has pretty good strength. Trying to fill a crack or anything structural in cast is asking for trouble. It really depends on the casting method. It can be done, I just don’t have good experience with it. Pre heating to molten temps will be your friend.

I used to TIG aluminum castings every day. We’re an aluminum foundry and, on certain jobs, were allowed by the customer to weld certain defects in certain areas of the casting. You need to know if the casting was made using one of the sand casting processes. If so, it is going to be full of trash. As the casting is heated, all of the sand, process coatings, and such that are in the porosity are goi no to float to the top, the molten area. When our guys were welding, you could see them flicking the filler rod. They were flipping the trash off as it floated to the surface. If the casting was made in China, Korea, or India, this problem will be even worse.

Use the jb weld for that. By the time you take it off and have it welded you can buy a new one and it more than likely won’t hold with cast aluminum

That's the key, you have to burn the impurities out and the success depends on the material.

75/25 helium/argon is your friend when welding dirty aluminum. It’s gotten very expensive in the last year though. Doubled in price. I keep a bottle on hand but it’s hard to go back to straight argon because the 75/25 burns really clean and really hot. Less amperage is needed.

You work at that foundry in Talladega? I'm going to contact them soon about some castings.

No, sir. We’re in Sylacauga.

10-4

Thanks for all the input. I don't know how to post pic. When I initially priced the pump online, it was giving me a range of $1600-$2000 just for the pump. My buddy checked and was finding them in the $350-$450 range. Maybe the difference between new and remanufactured, idk. Anyway, I ordered one for $355. I figured it was worth that to not wonder if the weld would hold. When the casting broke, the vibration wound up breaking the injector leak off line. That was the first indication that something was wrong but I still didn't realize there was an issue with the pump because it all ran normally. After I replaced the leak off line, it promptly broke again and the pump started leaking oil. So I really prefer to put in another pump so I don't have to wonder if the repair will hold and if it doesn't, is it going to tear something else up.

Thanks again for all the input.