Hi guys as u can see from pic i cracked my lower casing on a flop, i got a good welder that said it can be welded but HIS main CONCERN is THE GASKET between the lower and upper casing... it looks rubber to me so im assuming its just gonna melt and im screwed ... does anyone know wat kind of stock gasket is in there is IT A HI TEMP??? etc... so CAN i get some opinion on how this is going to turn out after he welds it...... is this a 50/50 shot that im gonna have to take the engine off and redo the lower casing gasket??? PLEASE HELP!!!! see pics PLEASE

 

If your referring to the seam that can be seen in the pictures it's not a gasket, just case sealant. Sometimes it's just plain black RTV, or sometimes similar to the weird yamaha stuff. Either way don't expect it to put up with more than 400F or so. The nice thing about aluminum is how fast it dissipates heat. If your welder is patient he'll just do a dot at a time giving a break for cooling and very little heat will reach the mating surface. You really don't have anything to lose by trying, right?

 

I had a old 86 toyota truck that had a crack in the block granted this is bad very bad and I didn't knowbwhat to do so I went to my dad his sugestion was jbweld it close well I was concerned it would still leak it it wouldn't hold for that long... its been almost six years not a drop has leaked and the cra k hasn't spread

Edit: This may or may not work in your scenario you said craked I just looked at the pictures I would say broke a chunk off

 

JB will probably hold it fine. I used it to hold a stripped spark plug in for 300 miles to get home before it blew the plug back out. Amazing stuff.