....is it an acceptable method for repairing a crack?

 

I wouldn't recommend it. Wire-feed welding is, by nature, porous. Personal experience, trying to weld beadlock rings onto my wheels... they leaked like crazy until the 3rd pass.

Plus, MIG welding Aluminum is a pain.

I would have it TIG'd.

 

TIG is gonna be the way to go!

 

I agree with Eskimo. You need a high frequency rig and tig process to properly weld aluminum. I do remember about 15 yrs ago that a DC stick rod came out for welding light gauge aluminum. It had a special flux on it that made an awful mess, + the weld itself did not have the flowability of what a tig weld has... Just my $.02 worth..

Gary