ENGINE TEMPERATURE CHECK
IMPORTANT: The engine temperatures listed below are based on an intake water temperature of 70° ± 10°F (21° ± 3°C).
Install correct test propeller and place outboard in a test tank or in the water. Start outboard and run at 3000 RPM in FORWARD gear for at least five minutes. Remember, running outboards at high speeds in test tanks may disrupt water flow to gear case water intakes. Make sure the outboard has adequate water flow.
When servicing the propeller, always shift the outboard to NEUTRAL, turn the key switch OFF, and twist and remove all spark plug leads so the engine cannot be started accidentally.
Reduce speed to IDLE for five minutes. Check IDLE operating temperature.
Increase speed to 5000 RPM and check temperature.
Check temperature on both sides of power head. If engine temperature is not within range, trouble shoot cooling system.
If engine temperature tests within range, but the engine monitor display indicates a “WATER TEMP” warning, refer to WATER TEMP/ HOT Circuit Test on p. 108.
Software Method
Use Evinrude Diagnostics software to read temperature displays.
Engine Monitor Screen
Typical temperature displays at IDLE speed should be 160°F ± 20°F (71°C ± 11°C).
Typical temperature displays at WOT speed should be 120°F ± 20°F (50°C ± 11°C).
Operating temperature must not exceed 194°F (90°C).
Pyrometer Method
Use a Temperature Gun, P/N 772018, or a digital pyro meter to measure the outboard’s operating temperatures.
Measure temperature of the thermostat housing at the top of each cylinder head.
Temperature Gun, P/N 772018
Typical pyrometer readings at IDLE speed should be 150°F ± 20°F (66°C ± 11°C).
IMPORTANT: If you get low or inaccurate readings with a digital pyrometer, coat the probe location with Thermal Joint Compound, P/N 322170.
Idle Operating Temperature Troubleshooting (Below Range)
If engine IDLE temperature is below operating range 160°F ± 20°F (71°C ± 11°C), check thermostat and pressure relief valve operation.
Pressure Relief Valve Inspection
The pressure relief valve should be closed at IDLE speed. Water should not flow past the plunger and seal.
Start the outboard and check IDLE operating temperature.
If IDLE temperature is too low, check pressure relief valve plunger and seal for damage or debris that could prevent the valve from closing completely.
If IDLE temperature is still below operating range, replace pressure relief valve assembly and plunger seal.
To test pressure relief valve operation, monitor temperature at the thermostat housing with Temperature Gun, P/N 772018, or digital pyrometer. Confirm normal IDLE operating temperature.
Slowly increase engine speed from IDLE, up through 3000 RPM. Engine temperature should decrease from normal IDLE temperatures as pressure relief valve opens. Valve should open at approximately 2500 RPM. If temperature decreases at a lower RPM, replace pressure relief valve assembly. Refer to PRESSURE RELIEF VALVE SERVICING on p. 192.
Thermostat Inspection
If IDLE temperature is still below operating range, inspect thermostats and thermostat seals.
Check position of thermostat seal and how thermostat seals against cylinder head. Seal must be properly fitted to flange of thermostat.
- Thermostat seal
Check thermostat for cracks, heat damage, or signs of corrosion. Check for proper operation. Thermostat opens at 143°F (62°C).
Refer to THERMOSTAT SERVICING on p. 191.
