I recently purchased a 1994 30 ft Scarab Sport w/ twin 1994 Yamaha 225 hp saltwater series 76 degV outboards. Motors have approx 530 hrs each. Both motors generally run fine with the excption that the starboard motor has a tendency to overheat when I flush out the motor on the trailer using muffs. The motor will overheat after running for about 5 mins. I am getting a steady flow out of the telltale during flushing. The motor does not overheat when operated in the water. Any suggestions?