6.2 porous block?

Blue Ox · May 8, 2020

84 M1008 said:
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.

First step is clean off the JB Weld and see what really goes on. Then we can look at the other things. They're not the greatest engine ever designed, but they're not the worst either. My second one went 200K miles before it broke the crank. Others have gone a lot longer. One local bus company that I work with had a fleet of 6.5s that had multiple rebuilds and never a cracked block. So it's possible for them to wear out instead of breaking.

84 M1008 · May 8, 2020

I have to run this thing until I can get it to sweat and see if does leak through the block. I had cold garden hose water going to it when I test ran it with the thermostat removed.

TheGoose · May 8, 2020

We’re fixing up our old truck that has 213,000 on the 6.2l block.

84 M1008 · May 10, 2020

Well it's official, this block is junk. I ground off more JB weld or WHATEVER TF the previous owner smeared on it and found two hairline cracks. Look in between the red sharpie lines just above the arrows. I paid $700.00 for this POS.

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Customblue · May 10, 2020

Ive heard of welding the block, I know I'm not capable of doing it but I'm sure there are those who are

78C10BigTen · May 10, 2020

84 M1008 said:
Well it's official, this block is junk. I ground off more JB weld or WHATEVER TF the previous owner smeared on it and found two hairline cracks. Look in between the red sharpie lines just above the arrows. I paid $700.00 for this POS.

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I think that guy saw you comin.

Vbb199 · May 10, 2020

I say weld it,

preheat first to 600 or so degrees, weld it at a low amperage. if you wanna keep it from cracking ever again, drill small holes at the ends of each crack to stop it from continuing , then weld the length of the crack up.

Cracked blocks isn't something to be too too scared of....

Warped blocks, or blocks with excessive core shift is something to be scared of.

There's also block stitching, I've seen people do that **** with #53 Cummins blocks.

Optionally.... Go beat that guy's ass! :boxing:

84 M1008 · May 10, 2020

That Detroit 4-53T swap is looking better now.

84 M1008 · May 11, 2020

I just regained consciousness, I'm looking at a rebuilt 6.5 Navistar GEP engine for it.

CORVAIRWILD · May 11, 2020

I have 290k on my 6.2 Suburban, towed PLENTY, up mountains, overloaded... gets hot, cools down, runs fine

I broke a crank in a 6.2, it was badly abused, bad damper

I plow with an '84 K5 Blazer 6.2, 139k, runs like new, starts without block heater below 0f

I have a '95 6.5 Suburban w 309, runs great, a little blowby, doesn't like to start cold, even with 7 new glowplugs

I suspect the block cracks are from freezing... my 2 cents

Welding exterior water jackets isn't out of the norm. I just watched a video from Nick's Garage of a 426 HEMI with a welded block. It's "just" the water jacket...

Can I see what the cracked main webs looks like?

I have a number of other 6.2s and 6.5s, they're reliable from 13 years of my experience

Blue Ox · May 11, 2020

CORVAIRWILD said:
Can I see what the cracked main webs looks like?

I don't have a picture, but they crack from the outer main cap bolts up to the cam bore. On mine you could wiggle one of the bulkheads. Except for the shape of the cracks holding it together the bulkhead was completely disconnected from the block. Some of the 6.5L engines where they first added piston cooling would crack where the holes were drilled for the cooling nozzle.

GM made a couple of changes to the outer main bolts during production. The first was to lengthen the bolts by 10MM. Later they reduced the diameter of the outer bolts. AFAIK it did reduce the cracking, but I don't think they ever truly resolved it.

84 M1008 · May 11, 2020

CORVAIRWILD said:
I have 290k on my 6.2 Suburban, towed PLENTY, up mountains, overloaded... gets hot, cools down, runs fine

I broke a crank in a 6.2, it was badly abused, bad damper

I plow with an '84 K5 Blazer 6.2, 139k, runs like new, starts without block heater below 0f

I have a '95 6.5 Suburban w 309, runs great, a little blowby, doesn't like to start cold, even with 7 new glowplugs

I suspect the block cracks are from freezing... my 2 cents

Welding exterior water jackets isn't out of the norm. I just watched a video from Nick's Garage of a 426 HEMI with a welded block. It's "just" the water jacket...

Can I see what the cracked main webs looks like?

I have a number of other 6.2s and 6.5s, they're reliable from 13 years of my experience

I haven't gotten that far yet have to flip it over and get the pan off it. I had a Banks turbo on my 86 M1031 and it ran fine. I don't know if I want to get into this thing too far.

CORVAIRWILD · May 11, 2020

I had a Banks on the 6 2 on which the crank broke. It really woke the 6.2 up!!

84 M1008 · May 11, 2020

CORVAIRWILD said:
I had a Banks on the 6 2 on which the crank broke. It really woke the 6.2 up!!

Yeah, mine would walk away from a 6.5 all day long. I had a built 700R4 behind it also.

Bextreme04 · May 11, 2020

I would bet it is from freezing as well. As others have said, it’s a non-structural exterior cooking jacket wall. I’d look for a skilled professional welder in the area to just weld the cracks up. It’s not terribly difficult and is probably MUCH cheaper than getting another engine.

6.2 porous block?

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