Overheating

[HKVolty]

Well. The original mechanic thinks its something to do with the cam being worn or the valves being messed up, havent opened it up to look yet though. I took it to another mechanic who was recommended to me, he immediate assumed the problem lies in the crankshaft?! He basically laughed at me and thinks the engine is toast. Said he could put a new engine in for $1000.

So I'm back at square one with an engine that is overheating and I don't know the reason. The oil pump is actually working fine as the oil actually dissapears from the sight gauge when I start it. Any more ideas? Would incorrect valve clearances cause an overheating condition? Does a lean mixture really cause severe overheating? Could it be a dirty carb? I've got a quote to replace the cylinder, piston and top end from a secnd hand engine for about $500 including labor and I'm thinking about doing it if its going to solve the problem.