Well, I just tore down my last two 6.2 cores today and low and behold, both have main web cracks-:t One engine was an 84 with about 200k on the clock and the other was an 88 with unknown mileage. I am kinda bummed because I wanted to put one of these together for a replacement engine for my daughter's blazer.:( None of these cracks are terminal, but I don't like cracks and these are the first 6.2's that I have taken apart that have had main web cracks with no other problems. Balancers and bearings were in good shape on both of these blocks. The last block I scrapped was a beloved 599 block from a 94 6.5. Maybe we should just run them until they break! Who know's how long the webs have been cracked.:confused: :confused: Maybe I should just go ahead and freshen one of these up and see how long it will run, after all, I will have to fix it anyway. What do you all think?

The rule of thumb for a gasser with a crack is two rules:

1) Drill a (small!) hole at the end of the crack to stop it from spreading.

2) Weld it up.

I've seen water jackets welded in this manner with no problems.

Unless you think it's a major structural issue, I'd be tempted to try it.

PS: You said Balancers can cause this? Is that common?

PSS: I wonder if a follow up grinding-polishing in this area would help to stress relieve the block?

They do it with connecting rods..

Some people seem to think bad balancers can cause this, but I am skeptical. The cracks always appear on the outside of the outer main bolt hole and run towards the cylinder from there. Some of the cracks I have seen are only about 1/2 inch long and others are about 1 1/2 inches long. I like to also drill the end of the crack, but on some of these, it would be tough, especially when they get to the lower under cut side of the cylinder. Welding the crack could also cause some other problems. Hmmmmm.

Hey! I just got the most awesome book today.. It's GM's "The 6.2 Liter Diesel"

Fantastic.. worth every penny.

Anyway, they talk about increasing the chamfer on those outboard main bolt holes to help relieve stress that builds up there.

That's where your cracks originate from, correct?

Maybe a good grind & polish with a deep chamfer would help stop this from happening in the first place.

Regards.

I like the idea!;)

PS: If anyone's interested, the GM Number on the front is:

16015.05-2

I dunno if they still make it, as I picked mine up used.. But it's an awesome resource.

The Military stuff I downloaded was pretty good, but this is the best resource I've found yet.

:ro)