Yeah, if pulling a hill and no noise at low rpm, probably not knock/ping. The main reason I suggested that was the warm/cold difference you mentioned.

I'm liking timing gear. The larger of the two gears is a fiber gear on a steel hub, and that fiber outer part of the gear will crack around that hub, and eventually break off entirely. Or if you've got a spoked aluminum gear in there, one of the spokes could be broken. Problem there is, I don't see how a failing timing gear would only make noise under load, nor should warm/cold make a difference.

You're sure it's in the engine and not, perhaps, clutch or transmission?

The video posted to youtube idea is a great one... that'd sure help!

Reason I asked where you were is that I'll be in Indiana next week with time to kill. Unfortunately, Indi area is exactly where we will not be :)

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-Matt I ♥ my ♂