470 I/0 overheat need help
 

Hey guys I need some confirmation here with my setup. Mercruiser 470 running hot- the raw water inlet hose is in the front on the heat exchanger right? Took that off seems like pressure coming out and spitting water? Thermostat works fine I took that out and boiled it in water and it opens at 160- I was having a over heat problem only at 3500 rpm and above but not it will boil over at idle if I let it run long enough. Took the risers off also they look perfect no derby or
Clogging ? I'm thinking maybe a head gasket?

Have you replaced the water pump impeller?

No I haven't changed that this season- boats in the water now so I would have to take it out to replace it. I'm going to stick a hose in the raw water hose today and run it

put a new raw waterpump in it, use a Mercury brand with a new upper housing, If any of the blades are missing, look in the rear of the heat excahnger for the missing pieces

Be sure to check your heat exchanger and if you have one, your oil cooler for blockages.