Ask The Experts | Remember to Flush

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[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Freshwater Flushing Adds Years to the Life of an Outboard
Article courtesy of Yamaha Outboards[/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Most of us take good care of our marine equipment. We wash and wax our boats and outboards, change the oil and oil filter regularly, and replace the fuel filters, but what about your outboard's cooling system. Unfortunately, it is often overlooked in a maintenance regimen. [/FONT][/FONT]


[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]art1_1.gif [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]During the course of normal use, the water pump can ingest mud, sand, and silt, which then flows through the engine. Marine growth can also occur behind the inlet screens interrupting the flow of water to the engine. Over time, debris can accumulate in the outboard's cooling passages. This build up can damage the water pump's rubber impeller and plastic housing. Eventually, the buildup can also restrict the amount of water available to the engine resulting in poor cooling, which will damage the engine. It may even promote corrosion in the exhaust system because increased engine temperatures–along with the effects of using ethanol blended fuels–can cause increased exhaust temperatures. [/FONT][/FONT]


[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Freshwater Flushing Facts
The outboard should be flushed after every use in salt or dirty water. Freshwater flushing with clean water will dislodge most contaminants (sand, silt, mud, etc.) and force them out of the passages in the cooling system. Perhaps even more importantly, flushing removes salt buildup, which can lead to poor cooling as well as corrosion of the engine block and midsection. \[/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Generically speaking, there are three methods to flush an outboard: using a flush bag, flush muffs or the freshwater flushing attachment built into many of the newer outboards.[/FONT][/FONT]


[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Flush Bag
A flush bag is a sturdy collapsible bag that fits under the lower unit of the outboard and fills with water. Submerging the gearcase allows the motor to take in cooling water from the inlet screens and return it to the bag through the propeller. There are different bag designs; some are designed to be used with the boat moored. [/FONT][/FONT]


[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]art1_2.jpg [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Use the Flush Bag method with the boat on a trailer or the boat moored at the dock. It requires running the engine (but only after the bag is filled with water). Outboards with more than one inlet on each side of the lower unit should be flushed using this method.[/FONT][/FONT]


[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]How to use the flushing bag: [/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Trim the outboard to the vertical position[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Remove the propeller[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Screw the garden hose into the connector on the bag and fill the bag[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Make sure the water level is as high as possible above the cooling water inlets on the lower unit. This will assure that the water pump is completely submerged[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Start the outboard and set the throttle to no more than a fast idle (800–900 RPM max)[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Watch for water coming out of the pilot tube at the lower rear of the cowling. Run the engine for 10-15 minutes. Note: it may take 20–30 seconds to fill the water passages before water will exit the pilot tube[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Stop the engine and turn off the faucet[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Never run the engine without cooling water[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Turn the freshwater on before starting the engine; turn the water off after stopping the engine[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Add water to the flush bag while the motor is running to maintain the maximum water level[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Do not leave the outboard unattended while running[/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif] [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Flushing Muffs (For models with single or dual inlet lower units)
Flush muffs are rubber cups that fit over the water inlet on the gearcase (one of the cups has a hose fitting). They require running the engine (but only after the garden hose is in place and water running). There are different styles of muffs so make sure you buy the type designed for your outboard or drive unit. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]art1_3.jpg [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Where: Best done with the boat on a trailer or a lift, completely out of the water. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]How to use the flushing muffs: [/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Trim the outboard to the vertical position[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Remove the propeller [/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Screw the garden hose onto the flush muff connector[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Place the flush muffs over the water inlets on gearcase[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Turn the water on slowly, until you can see a bit of water leaking from around the flush muff rubber cups[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Check to ensure the rubber cups are still in place over the inlets[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Start the outboard and set the throttle to no more than a fast idle (800-900 RPM max)[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Watch for water coming out of the pilot tube at the lower rear of the cowling. Increase the water flow, if necessary, to maintain a flow of water from the pilot tube. Note: it may take 20–30 seconds to fill the water passages before water will exit the pilot tube [/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]There should be some water exiting the back of the gearcase, through the exhaust also[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Run the engine for 10–15 minutes[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Stop the engine and turn off the faucet [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif] [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Never run the engine without cooling water. Turn the freshwater on before starting the engine; turn the water off after stopping the engine. Running the outboard with little or no cooling water will cause expensive overheating damage in a very short time. Don't rev the engine while using flush muffs, because there isn't enough water flow/pressure to sufficiently cool the engine at high rpm. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Built-In Flushing System:
A built-in flushing device is a hose fitting, usually located near the lower rear cowling. Different engine brands will have different locations to connect the flushing hose so check your owner's manual for your application. Do not run the engine during this procedure. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]art1_4.jpg [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]An outboard can be flushed with the boat on a lift or in the water; it works best if you can trim the engine up so the gearcase is out of the water. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]How to use the built in flushing system: [/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Connect a garden hose to the outboard's flushing device fitting[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Remove the propeller[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Turn on the faucet; let freshwater run through the outboard for 10-15 minutes[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Turn off the faucet; disconnect[/FONT][/FONT]
  • [FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Put the cap back on engine's flush fitting (per owner's manual) [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif] [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Which Method to Use
There is no single best method for flushing an outboard motor. There are only best methods to suit the circumstances. For example, the flush attachment method is the easiest and quickest for a boat that is moored, while the flush bag method is particularly useful on motors with multiple inlets per side. In addition, the flush muff method and bag method are the only methods to use when fogging the engine for winter storage. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]Testing has shown that even the flush attachment method allows water to pass into the cylinder head passages, in spite of the fact that the thermostat does not fully open. This means that there is no disadvantage to using the flush attachment. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]While conventional wisdom might indicate there is some benefit to flushing with the engine running–such as with flush muffs or a flush bag�there is no clear data to indicate this is true. [/FONT][/FONT]

[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif]What's important is to in all cases, regularly check to see that water inlet screens on the lower unit are clear and clean. Flushing your outboard with freshwater on a regular basis can go a long way toward extending the outboard's life span – especially for those who boat in saltwater. Freshwater flushing is easy and cheap, so keep the garden hose handy. [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][EDITOR'S NOTE] Find engine parts & maintenance supplies at iboats.com [/FONT][/FONT]
[FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif][FONT=Trebuchet MS, Lucida Grande, Arial, sans-serif] Article courtesy of Yamaha motors. For additional information on Yamaha boating, visit yamaha-motor.com. [/FONT] [/FONT]
 
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