I have a mercruiser 488 i/o. it overheats and the oil looks grey..i removed therm. and replaced carb.?

Question

any ideas?

Answer 1

Oil shouldn't look gray? It has to have a thermostat> 145 deg open system 160 closed> Check the risers>what was wrong with the carb??

Answer 2

H2O in black gold

Answer 3

You probably need a new impeller and must remove the old bits...try compressed air. Your exchanger is likely blocked and that lead to overheating. Now as a result of overheating...you need a new head gasket because you have water in your oil.  

Answer 4

   What did you remove? Why did you replace the carb.? Oh thermostat. Put a new one back in, according to a repair manual, boat engines can overheat by not having a thermostat. It no longer controls the length of time the cooling water is being held in the in the heat exchanger; which can cause you overheat! Wrong way to start diagnosis. Start by pulling hose end after heat exchanger.Hold hose even with top of engine or close, start engine and check water flow. should be at least half a foot. Rev up engine, water flow should increase. If it does not, have impeller checked and replaced. If the impeller is missing some vanes, you must find the pieces. They are probably blocking the intake of the heat exchanger.Pull  all the spark plugs and crank over engine while still hot; any water blown out means a  head gasket! Send out heat exchanger to have checked for cracks. That could be the milky oil. Good Luck! Those are Mercruisers own engines (aluminum) with a big block Ford head. Good engine,economical, but NEVER overheat them!