Overheating!!!

[pacman II]

1978 Mercuiser 470 3.7 2bbl.Carb W/salt water cooling system........

We have replaced impellor and housing--4" heatexchanger--Thermostat and
gasket--heat gauge and sending unit--discounted and blew air thru all fresh water cooling lines--replaced antifreeze--STILL OVERHEATING!!!!!
"ANY and ALL SUGGESTIONS APPREICIATED"

Also facing engine engine on right side on block there is a box looking thing that has fresh water in and out--and 4 wires hooked to it--What is it!!!

 

[CAPTKEV85]

Re: Overheating!!!

that block with the 4 wires is your regulator for the charging system. salt water passes through there to cool it. Check to see if it is clogged. Also grab the hose leaving the heat exchanger going to the riser when the motor is running. if that is hard as a rock then the riser is clogged.

 

[CAPTKEV85]

Re: Overheating!!!

welcome aboard by the way