The problem is the knurling on the crank. I have all the Chinese cranks sent to my crank grinder for check and correct anyway. We discovered that a .006 cut on the rear main seal surface knocks down the high spots and provides a smoother working surface. ALL of the premium cranks (Callies, Crower, etc.do NOT use the knurling and they never give you any issues with leaks)..I always use the orange "Fluoroelastomer" seal. It is the highest quality available, as far as I know. No leaks...
