knock

Anonymous-0 · Dec 27, 2011

I am working on a C-113 engine and it runs great no smoke and has decent oil pressure. It does have a slight knock once its warmed up. If you pull #1 plug wire it goes away.
Could it be a wrist pin or a rod bearing?
Just looking for a s.w.a.g answer!
Thanks!

rustcollector · Dec 27, 2011

Could be a bearing or wrist pin or piston slap from cylinder/piston wear or as simple as carbon built up on the head or top of piston. Typically carbon on top of a piston will quieten down with warming up the engine, but not necessary. I would try to find a scope to look in the cylinder through #1 spark plug hole before tearing down.

Janicholson · Dec 27, 2011

Wrist pins do make those disappearing noises. they also can run for tens of years with the same sound. If it gets worse, or starts knocking earlier, I would worry a bit.
Sometimes carbon (or a screw from the carb) can be found being pinched between the head and the crown of the piston. When the rod heats up, it hits the head. when cold it is not touching. Jim

knock

Anonymous-0

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rustcollector

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Janicholson

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