2008 Evinrude E-TEC 55MFE Technical Manual, Page 178Get this manual
COOLING SYSTEM OPERATION
OPERATION
All models use two-stage cooling system designThe cooling system is dependent on water pump pressure and controlled by thermostat and pressure valve operation
IMPORTANT: Restricted or inadequate water
flow through the outboard reduces cooling system performance and may lead to severe powerhead damage
At higher speeds, water pressure opens the pressure relief valve at approximately 1800 RPMWater flows through the valve to the cylinder head and bypasses the thermostatAll water flows through the cylinder head to the outlet passage of the block and then exits through the exhaust housing
EMM and Vapor Separator Cooling
Cooling water is routed from the top of the cylinder block to the inlet fitting of the EMM water cavityCooling of the EMM helps to stabilize the temperatures of internal components