Re: 9.9 evinrude discolored head
I wouldn't give up on the motor, especially since it did not seize. It would be advisable to replace the impeller and also check the impeller housing. If you are running in silty or salty water you should consider a h.d. chrome water pump. The h.d. impeller housing will not groove & wear out like a plastic one if silt or salt are present in the cooling water. You didn't say what year of motor you have, but assuming it is a 2-stroke, by your description it sounds like you should remove the exhaust bypass cover to see if the pistons or rings have any obvious damage. Even if they don't have obvious deep damage, it still may be best to remove the powerhead, remove the head & resurface the head & block mating surfaces. Before that it would be advisable to flush out your cooling system to make sure there isn't a blockage. If an impeller breaks up it can easily send rubber chunks into the cooling system & lodge in a water jacket somewhere, causing overheating & damage to the block. As for the flushing procedure it really depends on the year of your motor. Good luck!
