Cast aluminum pan. about a 1+ inch long crack right in front of pan, right behind frt diff. i can get spoolgun close enough i think, but am worried about fire inside the engine. is this a legit concern? I think if i drain the oil, then "Carb clean" the crack, then grind a bit to get to new metal, with some preheat, will this weld? or am i just going to keep getting oil oozing into the weld.

 

The only way I would attempt to weld that crack is with the oil pan removed from the engine. Otherwise, you are possibly looking at a whole lot worse than a leaking pan.

Try using some JB Weld first, that stuff works pretty good and lasts a long time. I used some on an aluminum canoe a few years back to seal up a crack and it is still firmly attached to the canoe with no leaks at all. Much easier and safer than trying to weld on an oil pan attached to the engine.

 

Ditto on considering JB Weld. I even fixed a rusted through steel pile pan with it.

 

i spose we try the "non" explosive repair first.

 

Personally, I wouldn't worry too much about explosion. You can always purge the crankcase with an inert gas first if it makes you feel better. BUT there's no way you'll ever get a decent weld on that thing because the oil will keep bleeding through the crack and screwing it up. Even if you remove it and think you've thoroughly cleaned it, you're going to have the same problem. The weld will be porous. Grind it for good adhesion and give the JB Weld a try. I would also stop drill the ends of the crack first to keep it from spreading.

 

it doesn't look like a serious impact caused the crack, but would broken motor mounts do it?

 

Not by themselves. But they could allow it to hit the crossmember.