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HotRod

The truck came in for a leaking radiator and CEL. The code 1328 fmi 31 was for #6 cylinder idle smoothness/misfire at idle, we ran the relative compression test several times and each time it pointed to #6 cylinder being at 5 or 6% while the other cylinders were above 90%. At that point we began to troubleshoot for any signs of damage. removed valve cover, inspected valve train, removed oil filter and found there was a metallic tint to the oil. dropped the oil pan, got an oil sample, and inspected everything on the bottom end. That is when we found the markings in the liner, and decided to pull the head for a further inspection and to ensure there was no damage to the piston or rings as well. 2 different oil samples from 2 different labs came back good with no signs of excessive metals of any sort. Once we had everything apart we could not determine any sign of an actual failure on that cylinder related to the markings. And as stated before it does not make sense for it to have failed while running because the marks would be vertical. We compared measurements of the #1 and # 6 liners, installed and removed, also the pistons, ring gaps, piston skirt, rod bearings, between #1 and #6. All is within spec of Detroit recommendations, and the same between the 2. We still have to check the rod to make sure there is no issue there, and we are also replacing the injector on that cylinder.

In short the motor came apart because the customer did not want that liner in their engine whether it was actually causing a problem or not.