Originally Posted By: 137_Trenton
It looks like it welded up pretty cleanly for you... was there a lot of [censored] floating up in the puddle? Which rod did you end up using? 4043? I haven't welded on aluminum in years but always hated doing the castings especially if oil soaked lol. It definitely looks like either a design flaw or a loose bolt that caused it. If it was me i'd probably throw some thread lock on the bolts too just so they don't come loose.
Any casting, alum, cast iron, cast bronze, will absord what every makes contact with it. Oil, minerals in water, etc. I cleaned the surface well, then polished the oxidation around the weld area. Groung out the cracks with a die grinder then cleaned again with brake clean to remove as much oil as possible. I did need to re-grind a couple of spots and re-weld.