[Bob from Northport]

The noise I am trying to describe at 40+mph is the sound a diesel engine makes when running. The engine and idles smooth, starts very easily. Changing the spark advance makes no difference in the noise-not detonation. The engine leaks oil badly from the rear main as well as a leak from the front. We did put MMO when we changed oil, but so far no change. The noise increases as the car accelerates above 40. There is nothing loose-brand new fresh rebuild on the entire car. If valves were sticking, I would not idle as smooth as it does.

Bob