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Thread: Early 6.2 "red" block.

  1. #1
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    Default Early 6.2 "red" block.

    Did the early 1982 6.2 "red" block have a forged crankshaft?
    1986 M1031, Banks turbo,700R4,4.56 gears.

  2. #2
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    No. Same as later model years.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
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    Thanks Dmax, just trying to clarify some info I found on another site stating that the very early, first production run of the 1982 6.2 had a forged crankshaft. It was also stated that the guys at Detroit Diesel had originally designed the 6.2 with a forged crank and the high nickle formula for the block. Also mentioned was the warning by the Detroit engineers to the powers that be at GM to not use a cast iron crankshaft. More 6.2 urban legend? Who knows. If this is true, we would probably never hear of broken crankshaft stories.
    1986 M1031, Banks turbo,700R4,4.56 gears.

  4. #4
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    That may be true of prototypes and pre-production engines, but I've never heard of or seen any in service. Duramax prototypes didn't have injector issues, but production models did in less time/miles than they did. Quality is only as good as the bean counters allow.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

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    Thank you again sir!
    1986 M1031, Banks turbo,700R4,4.56 gears.

  6. #6
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    I have heard the various stories about the "RED" engines, but as Maverick mentioned, these may have been related to prototype stuff, or just urban legends.

    The high nickel content of the casting story has been around for a long time, but I have never been able to varify any of it.

    I have torn down red engines with cracked blocks and broken cranks, that were no different than the later stuff.

    I have also read the history of the 6.2 design, and there is explicit reference to the choice to use nodular iron for the crankshaft, also there was mention made of "rolled" radii on the journals to strengthen the areas.

    I have to believe that DDA may have contemplated a forging for the crank, butttttttttttt, a forging is not something thats cheap to produce, especially for a small test run. (development) A casting is cheap and easy to do, even in low numbers.

    I am of the mind set that these engines never had a forging in the bottom end at any time.

    If DDA had really wanted to build a great engine, they would have used a deep skirt design, with cross bolt mains in the center 3 positions, and a forged steel crank. In addition the materials in the heads and the block would have been a high nickel iron, plus being heavier throughout.

    The heads also would have been beefier and have had 2 more bolts per cylinder to keep the clamping force stable.

    The use of TTY bolts has become a common practice, though possibly a poor choice.

    As Maverick mentioned about the bean counters, these guys have cost GM more $$$$$$ and tarnished their reputation over the years soooooooooo badly.

    To try and save a few $$$$$ per unit, but then loose it in warranty costs makes no sense.

    Once the particular package gets a bad rep, the customers will flee like rats off a sinking ship.

    Remember the 5.7 olds diesel ???

    When these were running, they were great, and got fantastic MPG's buttttttttt, head gaskets, cracked heads and other issues would plague these engines from the gitgo.

    The 6.2 was better, with far less failures, but, still not a stellar design.

    The 6.5 was ok too, untill the electronic injection made the scene in 1994
    From this point the engine was doomed. The cracked blocks, broken cranks and other anoying issues just drove more nails in the coffin.

    To put this in perspective, there were a lot of these engines that ran a lottttttttttttttttttttt of miles with no issues, but, there were enough troubles that the reputation was agained stained.

    A 6.5 with 200k on it is living on borrowed time, as the magic number seems to be about 230 to 250 k and the head gaskets are going to go away.

    I have seen these engines with 30k and break a crank. 200k and be perfect ?????????

    The blocks can crack ay any time, or live on to see 200k plusssssssssss without a single crack. There is no way to predict this either.

    My feelings after having been into a buttload of them is that the design is flawed, there are way too many stress risers in the bottom end and the material is less than optimal.

    The sharp edges in the bottom of these contribute heavily to a predisposition to main web cracks. This alone weighs heavily.

    This can be corrected easily, but it takes time and $$$$, especially during production conditions.

    The current engine I built for my 95 GMC saw several hours deburring and chamfering in the lower end.
    I chamfered every bolt hole in the bottom as well as the cylinder deck.

    Every main web had all the sharp edges removed and rounded slightly.

    The main registers had the bottom sharp corner radiused to remove the stress riser.


    GM chose to fit the main caps into a stepped cut in the mainline, leaving a razor sharp corner, which is an absolute engineering NO NO

    Cracks emanating from this area are common, as are cracks that start from the razor sharp edges of the bolt holes at the part line of the main cap and block.

    Just a myriad of loose ends in these engines that all add up to trouble.


    Missy
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  7. #7
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    Hea Missy, Always a pleasure hearing from you! As you know, I am a member here and over at the Steel Soldiers site. I am also a member at other GM related sites. The urban legend stories about these engines are endless, and could be made into some kind of twisted motorhead novel.

    As you know from my posts, I have one of these "Red" blocks in storage for a rainy day. I thought it was a keeper as it's been rebuilt and has managed to stay togeather for 75K, and was running at the time the truck it was in was rear ended and totaled. Lord only knows how many miles were on it when it was rebuilt.

    I figure if it hasn't blown up by now it was well worth the $500.00 I paid for it. It's complete down to the last nut and bolt, and the paint looks to be original. I also have an M1009 Blazer that looks like it's been sitting on the deck of the Titanic since 1984. A total rust bucket, and the odometer says 100K on it.

    It was barbarically converted over to 12v, and the wiring job looks like it would burn it to the ground if you were to just touch the key. That thing fires right up after a half a turn, has absolutely no blow by and has just a brief puff of black haze out what's left of the pipes! Go figure, LOL! ANYWAY, Thanks for all the usefull information. Wayne.
    1986 M1031, Banks turbo,700R4,4.56 gears.

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