I'm in the process of tearing down my motor for a rebuild project over the winter. Here, I'm at the point of no return. All 20 perimeter fasteners removed. Tomorrow I split it open.

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How do you determine if the engine has had a prior rebuild? All the hardware I've removed appears to all be the same (no mismatched fasteners). The nuts for the casethru bolts had a red threadlocker or case sealant on them.

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Here are the heads. I'm not sure what to look for in terms of them being flycut or having had work done to them.

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Sometimes it's obvious, but most of the time it's subtle things that come from having been into many motors. I don't see anything obvious that screams out REBUILD, but the pictures aren't hi resolution.

But even if you did see something there are so many levels of 'rebuild'. Heads redone, new pistons & cylinders, connecting rods rebuild, case split and everywhere in between.

I know mine wasn't rebuilt and it did not have red thread locker on anything.

The red on the nut is original. It's not a thread locker, it's a seal.

Yes, I should have clarified. The red is only on the top of the nut and appears uniform as if a machine applied it (perhaps at the nut factory).