Service Manual 250-300 HP 3.4 L E-TEC Cooling System
Start the outboard and check IDLE operating temperature using Evinrude Diagnostics software pro gram.
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 operating range with hoses pinched off, inspect thermostats and thermostat seals.
Thermostats
Remove thermostat cover(s) and inspect thermostat(s).
Check position of thermostat seal and how thermostat seals against cylinder head. Seal must be properly fitted to flange of thermostat.
- Seal, thermostat
Check thermostat for cracks, heat damage, or signs of corrosion. Check for proper operation. Thermostat opens at 143°F (62°C).
THERMOSTAT SERVICING
Disassembly
Remove the thermostat cover and O-ring from cylinder head.
Remove spring, thermostat, and gasket.
Inspection
Inspect all parts for cracks, heat damage, or signs of corrosion. Replace damaged parts. Clean debris from housing and parts.
Assembly
Assembly is the reverse of disassembly. Pay close attention when performing the following additional tasks.
Coat threads of each cylinder head thermostat cover with Gasket Sealing Compound. Install and tighten the cover to a torque of 120 to 144 in. lbs. (13.5 to 16.5 N·m).
