6.2 cracked blocks compared to 6.5

[Rob4]

Anybody have a feel as to which blocks are more prone to bottom end cracking--the 6.2 or the 6.5? Any difference in the early 6.2 blocks compared to the later 6.2 blocks? Also, what is the latest thought in rebuilding and using a cracked block that has the cracks that are still in the threads of the cap bolts? Are the cracks likely to creep on up the block later and cause a catastrophic failure?

[Robyn]

The 6.5 may be a little more prone to cracking , BUTTTTTTT I have seen all of them do it.

The 599 block which was used for late 6.2 and real early 6.5 has often been seen as the best one , but again I have seen them cracked too.

The best deal is if the cracks are not out of the bolt holes depth and into the web, to just do a Lock and Stitch Insert and be done with it.

This is a fully contained thread insert with reverse threads that pull the crack together the harder its tightened.

This system repairs and fully stops the crack from going any further and also if installed in holes that are not cracked prevents them from cracking.

I have seen 599 6.5 blocks with 250K+ miles and and zero cracks.
By the same token I have seen engines with less than 100K with half the middle main outer bolt holes cracked.

Hope this helps

Robyn