The Right Way
By John Tiger
The Old-School Way
Flush muffs are the most common way to flush an outboard; they're available at most marine stores and online resellers. They're inexpensive, and easy to use. Connect to a garden hose, fit the muffs over the engine's water intakes on the sides of the gear case, turn the water on, start the engine, and let it run. That's it, with the following precautions:
- If your engine has additional water intakes that are not being directly fed water via the flushing muffs, they must be sealed off with a bit of duct tape, or overheating may occur.
- If your engine doesn't have water intakes on the sides of the gear case, you will need a special type of flushing attachment that covers the front of the gear case. These can be purchased from aftermarket shops.
- When attaching the muffs, be sure they cover the water inlets completely and don't pop or slide off when the water is turned on.
- Be vigilant, and don't leave the engine while flushing. Watch the engine's "tell-tale" overboard water indicator to ensure that the engine is pumping water.
- The engine should be kept in neutral and not run above a fast idle speed (1,000 rpm maximum).
Built-In Flushing Attachments
Built-in garden hose attachments are a standard part of many outboards manufactured in the past decade or so. These attachments make flushing easier, because the engine usually doesn't need to be running (and in some cases, should not be) to accomplish the flushing procedure. Simply check to see if your engine has this attachment (look in the owner's manual), find the connection point, hook up a garden hose, turn on the water, and let it flow for 10 minutes. This is handy if you can't start the engine (dead battery, for example) or if your neighbors would balk at your engine's noise. Some caveats about using a flushing connection:
- Be careful not to cross-thread the connection. Many are plastic, and can be ruined quickly if threaded incorrectly with the brass fitting of a garden hose.
- Pay attention to the manufacturer's recommended procedure. See below.
Flushing bags are soft-sided heavy plastic/vinyl bags with a support framework, designed to be fitted up and around the lower end of an engine and fully enclose it. A garden hose is attached to fill it and keep water circulating; the engine is then started and run much the same as with a flush muff attachment. Flush bags allow for engine-on flushing without the loud noise of the engine's open exhaust. Online, google "outboard flushing bag," and several options pop up. As with other flushing devices, caution must be exercised:
- The bag must fit pretty snugly around the engine's midsection, and be tall enough to reach well above the water intakes.
- The propeller should be removed before installing the bag.
- As with a flush-muff attachment, engine speed should be kept to a fast idle, no more than 1,000 rpm. The engine should be kept in neutral.
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