Hey all, I am helping my buddy still with the 1953 3/4 ton with the 216. His engine runs smoothly, but has developed a deep sounding knock sound at certain RPM. Its sounds very deep in tone, coming from the middle area of the engine. I am thinking rod bearing-
We went through the valves and the obvious stuff. Could dirty oil cause this noise- I doubt it but thought I would ask here first before taking the pan off and checking the engine. Engine does have tendency to run hot when at speed- and cools off when you slow down. Does not overheat. Main bearings where checked and adjusted in accordance with the shop manual.

Thanks for the help.
Sam



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