COOLING SYSTEM
Regularly inspect cooling system components for corrosion, damage, leaks, or restrictions:
- water intake screens
- water pump
- all internal water passages
- thermostat
- all external water hoses and fittings
- vapor separator cooling passages and fittings
- EMM cooling passages and fittings
- overboard water pressure indicator.
For cooling system repairs, refer to COOLING SYSTEM on p. 169.
Water Intake Screens
Inspect condition of water intake screens. Clean or replace as needed.
Confirm function of overboard water pressure indicator.
- Water intake screen
- Overboard indicator
Engine Flushing
Flush the outboard with fresh water following each use in brackish, salt, or polluted water to minimize the accumulation of scale and silt deposits in cooling system passages.
The outboard can be flushed on the trailer or at dockside; running or not running.
IMPORTANT: The outboard must be located in a well ventilated area with appropriate ground drainage during the flushing procedures.
Keep water inlet pressure between 20 to 40 psi (140 to 275 kPa).
Flushing — Outboard Running
To prevent injury from contact with rotating propeller; remove the propeller before
flushing.
Place outboard in VERTICAL (DOWN) position in a well ventilated area.
Thread garden hose into flushing port.
TTurn water supply on.
Run outboard at IDLE only until full operating temperature is reached.
Leave the outboard in VERTICAL (DOWN) position long enough for the power head to drain completely.
Reinstall propeller (MRL).
Flushing — Outboard Not Running
Outboard can be in VERTICAL (DOWN) or TILTED (UP) position.
Thread garden hose into flushing port. Turn water supply ON.
Flush outboard for at least five minutes.
Turn off water supply and remove garden hose.
Position outboard in VERTICAL position (DOWN) long enough to allow the power head to drain completely.
Running the Outboard Using a Hose and Flushing Adapter
To prevent injury from contact with rotating propeller, remove the propeller before running engine with a flushing adapter.
A flushing adapter may be used to provide cooling water when running the outboard to:
- Flush the engine
- Run for an extended period of time, such as when performing diagnostic work
- Run the engine on a dynamo meter
- Prepare the outboard for storage.
IMPORTANT: The outboard must be located in a well ventilated area with appropriate ground drainage.
Keep water inlet pressure between 20 to 40 psi (140 to 275 kPa).
Be sure water supply is sufficient to run the engine above idle speed.
Water Supply Requirements
| Model | Water Flow @ WOT |
|---|---|
| 55 HP MFE | 4 to 6.5 GPM 1 (15 to 24 LPM 2) |
- GPM: Gallons per minute
- LPM: Liters per minute
Install flushing adapter onto gear case water inlet screens.
- Flushing adapter
A steady stream of water should flow from the overboard indicator while the engine is running. Monitor engine water pressure gauge when:
- Engine speed is above 3000 RPM
- Running engine on a dynamo meter.
Refer to SERVICE SPECIFICATIONS on p. 10 for water pressure requirements.
Engine will overheat if normal water pressure is not maintained. Temporarily install an engine water pressure gauge if not equipped with one.
