is there a way to fix a crack in a engine block?

yeah sell sell sell...! :P

wat about jb weld ? and its my baja not my split

dont think you can weld the block ,magnesium content

JB weld is ok for temporary... very temporary. I'd start looking for a new one.

Yer find another set M8.
Welding can be done at a desperate pinc but due to the amount of heat required to do the job correctly, you often end up with distorted cases and a big macining bill to straighten up the cam and crank tunnels.
If you want to come down to Tassie, I have a couple of cases (1x 36Hp and a couple of 1500's) here you can have LOL.

L8tr M8
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