How To Flush An Outboard Motor? 6 Essential Tips & Ways To Flush!

Any outboard motor operated in saltwater must be flushed with freshwater on a regular basis to keep it in good working condition. After every use in saltwater, most outboard manufacturers recommend a freshwater flush to clean the cooling passages of salt residue and scale that can build up and obstruct the flow of crucial cooling water through the engine. Outboards operated in brackish water or silty or muddy freshwater should also be cleansed. Flushing is usually a simple process that can be done while the boat is on a trailer or when moored at a dock or mooring. Check out the best boat muffs

The owner’s manual will include specific instructions for flushing an outboard depending on the brand and model. You might be able to find a digital copy of your handbook online, or a dealer can order a new print copy for you if yours is missing. If you don’t follow the directions carefully, you could damage the water pump impeller or flush the motor wrongly, resulting in an incomplete flush. Have queries regarding How to Choose Boat Propellers? Check out our guide on Boat Propellers to know more about how to choose the right boat propeller with all the necessary info.

Note: Never start an outboard motor without a water source; it must be submerged or linked to a hose that supplies water. The vanes of the rubber water pump impeller are lubricated by water, and running the motor without water for even a few seconds can damage or ruin the impeller. Looking for the Boat Fenders? Check out our Buyer’s Guide on Best Boat Fenders to know more.

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6 Essential Tips for Flushing an Outboard Motor:

  1. It’s important to remember that an outboard motor should never be started without access to water.
  2. For precise instructions specific to your brand or model, consult your owner’s manual.
  3. Make use of the built-in flush connection (if available).
  4. With a garden hose, install a flush muff over the cooling water inlet.
  5. Use a flushing bag or a bucket with a garden hose.
  6. Ensure that all freshwater has been drained from the motor after flushing.

3 Ways to Flush an Outboard Motor:

There are few ways to flush an outboard motor, and let’s check them out:

1. Built-In Flush Attachments

Most outboards made in the last 10 to 15 years feature a built-in flush connection that connects the motor to a garden hose via a snap fitting adapter or a threaded fitting. This fitting can be found on the motor facing the boat, beneath the cowl, or under a cover in the middle section. Outboards with this sort of fitting can often be flushed without starting the motor, and may even be designed to be flushed without starting the motor – check the owner’s manual for details. Are you searching for the best fish finders with GPS? Check out these from Garmin.

This type of flush connection can normally be used to flush the motor when it is tilted clear of the water if the boat is kept at a dock. Allow the water to flow for about 10 minutes after attaching the hose to the motor, or as directed in the owner’s manual.

2. Using Flush Muffs

Flush muffs resemble large earmuffs. The rubber cups are held in place by a metal spring or clamp that fits over the cooling water intake ports of the outboard gearcase. One of the rubber cups has a garden hose attached to it. Are marine binoculars helpful in boating? Check out right away

  1. The motor is started and allowed to idle in neutral after attaching the cups to the gearcase and initiating the water flow so that the propeller does not start turning, which would be dangerous if the freshwater was circulated through the motor.
  2. Water should flow out of the “tell-tale” as the motor starts, indicating that water is being pumped through the motor.
  3. As freshwater is pumped through the motor, let it idle in neutral for about 10 minutes.
  4. While the flushing operation is in progress, do not leave the boat unsupervised. The motor should be shut down instantly if the muffs fall off or the gearcase does not have a tight seal, else the water pump impeller will be ruined.
  5. Before turning off the water supply, turn off the motor. Muffs aren’t suitable for all outboards. Some have additional water inlet locations that must be sealed with duct tape if they are not covered by the muff. Others may have inlets that the muffs are unable to cover.
  6. Check the owner’s manual for detailed instructions once again. When utilizing flushing muffs, some require the propeller to be removed.

3. Flushing Bags or Buckets

flushing bag is a soft plastic, canvas, or vinyl bag that has a garden hose fitting. The bag is fitted around the gearcase and filled with water when the boat is on its trailer and the motor is tilted down, covering the cooling water inlets. What are the best GPS systems for your boat? Read through to find out

  1. When the motor is turned on, water will be pumped from this reservoir, and the water level will be maintained by the hose.
  2. Again, do not leave the motor unsupervised while flushing is in progress, and make sure the water is flowing from the tell-tale.
  3. A motor can be flushed in this manner with a big container or barrel as long as the water level in the container is kept above the gearcase inlets by a water supply.
  4. The propeller must be removed from the outboard to utilise most flushing bags.

Final thoughts:

After cleansing your outboard motor, make sure all the freshwater is emptied from it by following the owner’s manual’s instructions. This is especially crucial if the temperature is or will be below freezing; if water freezes in the engine, the engine block could be damaged. In most circumstances, all that is required is lowering the motor completely while keeping the boat level on its trailer.

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