2007 Evinrude E-Tec 75, 90 HP outboards Service Manual, Page 197Get this manual
COOLING SYSTEM COMPONENTS
Thermostat
The thermostat is used to control water flow and operating temperature at slower speeds (below 2000 RPM)Overheating: restricted or faulty thermostat typically results in LOW SPEED overheatingOvercooling: Debris may prevent the thermostat from closing completely4 1
Block Venting
A fitting and hose connected to the top of the exhaust cover allows the constant movement of water andor air from the blockCirculated water flows through the EMM and vapor separator before exiting through the overboard indicator