My '84 245 will turn over 333,000 miles sometime this week. The engine has never been disassembled. It burns maybe 1-1/2 quarts of oil between changes every 5,000 miles. I haven't checked the compression in quite some time, but the engine still feels strong and the gas mileage is normal (low 20's in town and 26-27 on the highway). I have noticed that the last couple of times it was smogged, it came close to flunking on CO.

Question is: At what point does this engine need to be rebuilt? It is not showing signs of giving up the ghost, but I am certain that if I tore it down right now, I would find measurable wear everywhere.

Has anyone rebuilt one of these, and am I doing any damage by running the engine until it dies? In other words, if it wears beyond a certain point (I am specifically thinking of cylinder wall wear) can it still be rebuilt?