Hi I had an atomic four for years and years I also used raw salt water for cooling. I also had many many problems. I think maybe you should take off the cooling line from the pump to the top of the engine There is a t-valve which puts cool water around the body of the cylinders. The is only the one entrance and exit. continuous use of salt water will leave deposits inside and finaly block off that entrance causing the engine to overheat at any revs above idle.