Pump casting is very porous, unfortunately this is what happens after welding.
It's porous but it does not have any oil impregnated in it like cases do , properly prepped and welded it should be fine , we used to have a guy weld up stator veins on Seadoo pumps years ago and when he got done you could tell it had been fixed because of the differences in the finish , but there were no voids and pits like I see going on here , if you have voids and pits you fill them in and grind it back down, the lob is not finished if you don't , this is what happens when you don't properly prep the Aluminum before welding it .
Tig welding Aluminum is very , very tedious work , the carbide bits you use to vee it out must never touch anything besides Aluminum , same with the stainless brushes used for cleaning , if you are sloppy you contaminate the Aluminum , after you get done with the carbide bits and the stainless brushes you wipe it with a clean cloth rag and Acetone , then you can weld it , even the oils in your skin can screw up a tig weld on Aluminum .
A little background here , I worked at a welding shop back in 2016-2019 , that's where my business was based out of, I did most of the steel welding there and we had guys come in to do the Aluminum , I was of course very interested in the whole Tig process and learned all I could from the guys there that did Aluminum welding , I can spool gun Aluminum pretty well but I have never tried to weld with a Tig , it's on my list to do this coming year and I have the Tig welder and the torch i just need to get an Argon bottle and regulator and get the water cooling on my machine setup.
