aluminum oil pan repair question

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Hi folks,I routinely do repairs on cracked or broken aluminum oil pans.  Today I did a job on a pan that had five small (an inch or smaller) separate cracks resulting from the driver going over a large hole left by city workers doing some pavement work.  After cleaning the various cracks and wire brushing them for welding I heated the pan up with a torch and sealed the cracks up using TIG.  I normally flip the pan over and weld the crack from the inside However this time I decided not to.  I put gasoline in the pan and swished it around to make sure there were no leaks.  I found two small pin holes that seeped, flipped the pan over, sealed them (after draining and drying the pan of course) and retested.  It was ok.The question I have is should I have sealed the cracks from the inside?  My thinking was that I had gotten good penetration welding on one side and could see the aluminum raised where my bead penetrated into the other side.  Anyone have any thoughts on this?Thanks for the feedback,Tony
Reply:TIG often has porosity problems in aluminum.  Gas welding or brazing would fill these holes without the porosity problems.Kevin / Machine_Punk from The Aerodrome Studio - Lincoln PowerMIG 210 MP - Meco N Midget w/custom welding station - Vintage Victor 100Current Projects: The Aerodrome Studio
Reply:I have run into this problem more with aluminum castings that have held gas than with oil.  Seems counterintuitive.  Did your welds have any black spots?Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Originally Posted by Machine_PunkTIG often has porosity problems in aluminum.  Gas welding or brazing would fill these holes without the porosity problems.
Reply:On dirty cast a guy should go over the area with just the torch first to bring up any contaminants, clean again, then weld.I usually only weld one side of pans, shouldn't be much forces in them.
Reply:Thanks for the replies.  I mainly wanted to know if welding one side on such repairs is acceptable.  From hearing your responses I know others use this approach as well.  I didn't want to sacrifice quality of the job for speed.  That's a nice job on that pan VPI.  Since being in this trade for decades, I find that I like to see other welder's work.  Sometimes I say to myself "I never would have thought of doing it like that" when I see a tricky repair or fab job.  I think at heart we are artists.Thanks,Tony