On most outboard engines the cooling system is made up of passages inside the powerhead and cylinder heads, a water pump to transfer coolant and a thermostat sensor to control water temperature of the engine coolant, as well as a few other parts.
Using a flushing attachment is extremely important part of regular maintenance, especially when boating on salt water. Flushing the cooling system on your Evinrude E-TEC boat motor after each use will prevent buildup of salt, which can block the cooling system and lead to overheating problems. A build up of salt will also corrode your boat motor from the inside out.
There are a few additional steps you should take aside from flushing the cooling system, such as checking the condition of your engine’s cooling system components. Make sure you check…
- Water pump is working
- Water intake screens
- All external water fittings and hoses
- Internal water passages
- EMM cooling fittings and passages
- Overboard water pressure indicator
- Vapor separator finings and cooling passages
Always flush your Evinrude outboard with clean water after boating in polluted, salt or brackish water. Cleansing the outboard by causing large amounts of water to pass through the cooling system after each use will minimize accumulation of silt deposits inside cooling water passages.
You can flush the boat motor even if it is running or not. It can be flushed while on the trailer or at dockside. But always make sure you flush the engine in a well ventilated area and an area that has sufficient ground drainage.
Ideal water inlet pressure should be somewhere between 20 psi to 40 psi (140 to 275 kPa).
Flushing your outboard with the engine running
It is highly recommended you remove a rotating propeller before flushing to prevent injury. Refer to Propeller Installation on the factory service manual for removal procedures.
- Position the outboard in a vertical (down) position.
- Make sure the outboard is in neutral position with the propeller removed.
- Turn the water supply on.
- Start the engine and run the motor at idle only.
- Turn the motor off. Then turn off the water supply and remove hose from engine.
- Leave the Evinrude outboard in the vertical position for enough time to allow the engine block to completely drain.
- Lastly, reinstall the engine’s propeller.
Flushing your outboard when it’s not running
When you are flushing the motor while it is turned off, it can be in the tilted up or down position.
- Thread the garden house into the engine’s flushing port.
- Turn the water supply on.
- Flush the outboard engine for no less than 5 minutes.
- Turn off water supply and remove the hose from the engine’s flushing port.
- Lastly, place the outboard in the down position to allow the engine block to drain completely.
These cooling system flushing procedures apply to all 2009 79 cubic inch, 3-Cylinder Evinrude 75hp, 90hp E-TEC models, including engines with the following model numbers…