Service Manual 5007213_Evinrude E-TEC 115-200 HP Cooling System [Components]

All models use a two-stage cooling system design. The 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.

External water intakes mounted in the gearcase housing collect water and must supply the inlet side of the water pump with an unrestricted and unaerated water supply. Water is drawn into the water pump through a hole in the lower plate of the water pump assembly. All cooling water to the powerhead is provided by the water pump.

• A nylon wedge (impeller key) is used to engage the impeller bushing and driveshaft.

• The nylon impeller housing with stainless steel liner must seal against a separate stainless steel water pump plate.

• The pump operates as a positive displacement pump at LOW speeds (below 1500 RPM) and as a centrifugal pump at HIGHER speeds.

Refer to WATER PUMP on p. 311 for water pump servicing.

(Impeller key removed for clarity)

1. Water inlet

2. Water outlet

3. Seal

4. Plate

5. O-ring

The water pump outlet connects with the water supply tube located in the outboard’s midsection. Grommets seal the water tube to the water pump housing and the inner exhaust housing.

Water supplied to the water tube provides all cooling water to the adapter housing and cylinder block.

• Adapts the cylinder/crankcase assembly (powerhead) to the exhaust housing and the water tube.

• Provides water passages which route incoming and outgoing cooling water.

• Provides exhaust passages which connect to the lower inner exhaust.

1. Adapter/inner exhaust housing

2. Water tube(s)

A pressure relief valve is used to control water flow and operating temperature at higher speeds (above approximately 2500 RPM / 21 PSI). Pres sure relief valve activates or “blows-off the seat” as water pressure increases. Spring tension is used to set the “blow off” pressure.

Overheating: A restricted or faulty valve typically results in HIGH SPEED overheating. (Minimum water pressure at 3000 RPM is 21 PSI.)

Overcooling: Debris may prevent the valve from closing completely.

Pressure Relief Valve Components

Thermostats are used to control water flow and operating temperature at lower speeds (below 2500 RPM).

Overheating: Restricted or faulty thermostats typ ically result in LOW SPEED overheating.

Overcooling: Debris may prevent the thermostat from closing completely.

Thermostat

Refer to THERMOSTAT SERVICING on p. 233.

A fitting and hose from the top of the block allows the constant movement of water and/or air from the center water passage (top) of the block. Circulated water flows through the EMM to the Vapor Seperator and then overboard through the water outlet fitting in the rear exhaust grommet.