I have a 1996 5.7 Merc Alpha 1 that I changed to fresh water cooling. with salt water it used to rum at 160 now with fresh it will run to 200+<br /> I have changed the engine pump, new out drive pump. Flushed the system a hundred times. All with no luck below 3000 rpm it will run all day at 175 - 180. Could it be I need a engine driven raw water pump for more water flow with the Alpha drive? and can I "T" them to feed the engine? I have a through the hull fitting in place for the AC so that is not a problem. Need some advice on this one........ Thanks