I have an 87 supra that just recently started overheating. Replaced raw water pump impeller, replaced main engine water pump. still overheating. I verified sea strainer was not clogged and that water lines were not clogged into raw water inlet. Lines are not clogged into thermostat housing, I have no thermostat installed and have ran it this way for years with no problems. I am not sure if water is exiting rear before anyone asks because but is still currently in the water. what could possibly be stopping the water flow or what is another possible problem. Once I get it out of the water I intend on checking for flow by hooking up a hose at the raw water inlet as I always do to run it on land. I hook hose directly to cooling line before sea strainer/cooler. Possibly traps at back of boat exhaust, block blockage? all thoughts and ideas appreciated.