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Date: October, 2005 No. 2005-05(S)
MODELS: 2005 Evinrude® E-TEC 200-250 HP SUBJECT:Engine Idle Operating Temperature

Dear Evinrude/Johnson. Dealers:

This communication is to inform Evinrude dealers of the importance of properly verifying engine IDLE operating temperature on Evinrude E-TEC 200-250 HP outboards.

Certain conditions can prevent the engine from achieving proper IDLE operating temperatures. Failure to achieve specific operating temperatures can result in running quality issues and premature spark plug replacement. Always verify IDLE temperature prior to troubleshooting an outboard for running quality issues or spark plug replacement.


Observe IDLE operating temperature for both port and starboard cylinder heads. Two methods can be used.

Method 1

Use Evinrude Diagnostics program. Observe temperature displays for port and starboard temperature sensors.

Typical temperature displays at IDLE speed should be 160°F ± 10°F (71°C ± 6°C).

Method 2

Perform this procedure on both port and starboard sides of cylinder block assembly.

Use a temperature gun (infrared) or a digital pyrometer to accurately determine the outboard's operating temperature.

Position infrared beam or pyrometer pickup on top of cylinder assembly, adjacent to the thermostat housing at top of cylinder head. Check temperature on both sides of powerhead.

Typical temperatures observed at IDLE speed with pyrometer should be 143°F ± 15°F (62°C ± 8°C)


If engine temperature is not within specified range, troubleshoot cooling system to determine problem.

Check thermostats and pressure relief valve operation if engine temperature is below normal ope-ating temperature. Remember, cold running outboards prevent spark plugs from achieving proper operating temperatures.



Pressure Relief Valve

Verify engine temperature at IDLE. The pressure relief valve should be closed. Water should not flow past the plunger and seal at IDLE speed.

If IDLE temperature increases to specific operating range, pressure relief valve and thermostats are functioning properly.

If IDLE temperature is below specific operating range, pinch off the water outlet hoses from pressure relief valve to cylinder heads.

Use the appropriate hose pinching pliers (acquired through local tool source) to prevent hose damage.

Start the outboard and check IDLE operating temperature using Evinrude Diagnostics software program.

If IDLE temperature increases to specific operating range, 160°F ± 10°F (71°C ± 6°C), after pinching off hoses and eliminating water flow to the cylinder heads, pressure relief valve is leaking. Replace pressure relief valve.

If IDLE temperature is still below specific operating range with hoses pinched off, inspect thermostats and thermostat seals.


Remove thermostat cover(s) and inspect thermostat(s).

IMPORTANT: Check position of thermostat seal and how thermostat seals against cylinder head. Seal must be properly fitted to flange of thermostat.

Inspect thermostat for cracks, heat damage, or signs of corrosion. Check thermostat for proper operation. Thermostat opens at 143°F (62°C).