I believe they traced the cracking problem to the fact that they were machining the engine blocks while they were still too "green" and the tolerances were changing after the block had some seasoning to it. Hence the cracks in the corners where they join with the main caps, and the main bolt hole cracks. Remember that these are low rpm engines - under 4,000 rpm max.
Back then they were making these engines as fast as they could churn them out, and selling them as fast as they made them. When the military HUMVEES went to the 6.5, AM General bought the rights to the engine and completely redesigned it to get all the stupid issues solved - cracking blocks, cracking heads, bad coolant flow to cylinder 7 and 8 (exactly where my headgasket blew out in 2103).
At least I can pride myself on the fact that the inside of the engine was spotless - no sludge, grunge, or caramelized residue anywhere...and for a diesel no less! I guess that's what 22 years of oil changes at 3,000 miles can do. All I ever used was the Rotella 15W40 and AC/Delco or Napa Gold filters.
Last edited by njsteve; 07-13-2017 at 02:16 AM.
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07-13-2017, 01:20 AM
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