Well, the prognosis only gets worse... I pulled the #8 piston Sunday and found what looked like 2 scratches in the cylinder wall, which assumed to be from bits of the air cleaner stud scratching it in a couple places while the piston rode up and down. I gave it a light hone to see if they would clean up, then examined them more closely; one of them is definitely not a scratch! It's clearly a crack, located at about 7 o'clock as you look down the cylinder. It's an inch or so from the top and extends to about half way down the bore, maybe a little below, near where the bottom of the piston would. My thought is that when the piston hit the bolt at the top of the cylinder and caused the engine to stop suddenly, the extreme force at the very top edge of the piston may have caused the piston to rock in the bore and crack the block, as this spot pretty closely aligns with the bottom edge/point of the piston skirt, right where it comes back up toward the pin. That's all that I can figure. You'll notice in the picture that there are matching depressions in the cylinder wall at 4 o'clock and 7 o'clock which is where the bottom edges of the piston skirt would have pushed on the cylinder wall. When I ran the hone in the bore, these spots weren't even touched by the hone, which means the cylinder wall is pushed out in those two spots.
quote:do you think you would be able to tell if the bearing got damaged?
FWIW, I did measure the bearing in multiple spots and didn't find detectable bearing crush from the impact. Top and bottom half bearing measurements were very consistent with one anther, with only about ~1 thousandth's difference between side and center measurements.
Another engine pulling party to be scheduled soon. Stay tuned!
