6.2 porous block?

[84 M1008]

I was starting to prep an engine I bought last year to swap into my 84 K30 and found what looks like JB weld smeared on the block right under a freeze out plug. Are these engines known for porous block castings? I don't see any cracks but that doesn't really mean anything.

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[nabeshin]

I'd pressure wash that area real good and look for a hairline crack. I don't think people just smear JB weld onto engine blocks for fun.

 

[Blue Ox]

Ours went porous at 60K miles, but it leaked into the oil, not outside. GM didn't want to know $#it about warranty so we ended up having to buy a new engine. That finished the old man on GM.

I'd chip that stuff off so you can see what really goes on. But obviously if somebody was shmearing it, something's wrong.

 

[84 M1008]

Would the factory do that, or would they reject the block? From what I understand, the factory rejected a ton of these early 6.2 blocks due to poor castings.

 

[84 M1008]

Ours went porous at 60K miles, but it leaked into the oil, not outside. GM didn't want to know $#it about warranty so we ended up having to buy a new engine. That finished the old man on GM.

I'd chip that stuff off so you can see what really goes on. But obviously if somebody was shmearing it, something's wrong.

Now I'm a little leery about using this engine. I'm going to wheel that area down to metal and see what's going on with it.

 

[Vbb199]

Make sure to inspect around the mains on it too!!
There's alot of lore about cracks at the mains.

If we're referring to the diesel 6.2 that is

 

[84 M1008]

Make sure to inspect around the mains on it too!!
There's alot of lore about cracks at the mains.

If we're referring to the diesel 6.2 that is

I'm well aware of the web cracking lore. It's the result of running a 6.2 like it's a 454.

 

[Blue Ox]

Would the factory do that, or would they reject the block? From what I understand, the factory rejected a ton of these early 6.2 blocks due to poor castings.

No, the factory would not do that.

The mains cracking is just pi$$-poor design. Has nothing to do with the use of the engine, unless you're modifying it for drag racing or something. The problem was never really solved. When Navistar took over production for the military they had to put a giant girdle on the bottom of the engine to keep it together.

 

[Vbb199]

No, the factory would not do that.

The mains cracking is just pi$$-poor design. Has nothing to do with the use of the engine, unless you're modifying it for drag racing or something. The problem was never really solved. When Navistar took over production for the military they had to put a giant girdle on the bottom of the engine to keep it together.

Some of the issue that makes the hairline cracks grow into throwing a crank out is bad dampeners...

NOBODY checks their dampeners, and if they do, they don't replace it high quality dampeners, like the fluidampr

It's already a unbalanced, noisey, knocking piece of ****, put a O'Reilly dampener on it or let the one from 1985 stay on there until 2020, and watch the mains crack and bust, and throw a crank out at the pavement

 

[Blue Ox]

The damper isn't cracking the blocks. The blocks crack because the bulkheads are paper thin. GM made a number of modifications to the outer main bolts over the production life of the engine to try to mitigate it. OTOH, they never changed the damper design. They never solved the problem because it was inherent in the design, and without changing the bore spacing, or putting a huge bedplate under it like Navistar did you're never going to resolve that. Bad dampers will break cranks, but have you ever heard of one causing a block to crack in any other application?

 

[Vbb199]

The damper isn't cracking the blocks. The blocks crack because the bulkheads are paper thin. GM made a number of modifications to the outer main bolts over the production life of the engine to try to mitigate it. OTOH, they never changed the damper design. They never solved the problem because it was inherent in the design, and without changing the bore spacing, or putting a huge bedplate under it like Navistar did you're never going to resolve that. Bad dampers will break cranks, but have you ever heard of one causing a block to crack in any other application?

Yes, I know. I I guess I should have said the pre existing hairline cracks grow into something worse because of ****** dampeners.

My apologies, didn't mean for that to come out sounding smartass

 

[Blue Ox]

Yes, I know. I I guess I should have said the pre existing hairline cracks grow into something worse because of ****** dampeners.

My apologies, didn't mean for that to come out sounding smartass

It didn't. I see your point, I was just trying to clarify. I didn't mean to sound like a smart@$$ either. I've endured the joy of a broken crank from a cracked block, so I guess I'm too familiar.

 

[Vbb199]

It didn't. I see your point, I was just trying to clarify. I didn't mean to sound like a smart@$$ either. I've endured the joy of a broken crank from a cracked block, so I guess I'm too familiar.

That's why I say "lore", I myself have alot of lore about it, I'm not a fan of the 6.2, and if I ever have another truck with one in it, it'll get yanked and sold, just too risky grounds to be expecting it to be a long lasting investment.

 

[Vbb199]

I would like to know about the JB weld though. Because I've also heard of the blocks having cracks.

 

[84 M1008]

I don't know what I'm going to do now. This engine supposedly has 85K miles on it which I suspect is BS seeing as it has a rebuilt IP and rebuilt alternator. It ran great when I pallet ran it. It lit right up with no smoke or noise other than these things sound like they are coming apart normally anyway.