Hairline Crack in LM7 5.3 Block

[bnorth]

I would clean it up and try some JB weld. Failing that I would grind it open a little and weld it.

[87max]

went through a similar scenario years ago, Had a pro welder try to weld a hairline. After hours of attempts we never got it sealed. Naturally we cleaned it several times before hand. Tried jb over the welds- nope. For the additives some swear they will partially clog up radiator & other components. It has to go somewhere right? In the end drove it till it died & a buddy bought it & dropped in a diesel.