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Maintaining Your Boat's Cooling System

Florida fishing boats require special attention to cooling systems.



It's easy to lose track of time during those long summer days on the water. It's also easy to forget that grasses and stirred-up sediments may compromise your engine's cooling system. On coastal water, salt water itself, over the long term, is a threat. Whether you're fshing bays, the open sea or freshwater lakes, monitoring cooling water fow and engine temperature are a must. Here are some tips:

›› Flush, and flush often. In Florida's sediment, shell and marl-laden shallow bay waters, there will be deposits formed on and in the cooling galleries of your engine. Flushing your cooling system with fresh water after every run in salt or shallow waters is a must to increase engine life.

Most modern outboards are equipped with a fushing port that allows a regular garden hose to fush freshwater through the powerhead cooling galleries. This provides fushing from the powerhead down through the water pump system itself and around the exhaust jacket. The procedure varies among manufacturers. Some motors should not be fushed when the motor is on the traveling stand or in other words tipped up; check your owner's manual. Also, some motors must be fushed while the motor is idling to ensures fushing will occur throughout the entire system. Again, check your manual.

Older model and some lower horsepower motors still require “earmuffs” to be placed at the water pickups on the lower unit. In this case, the engine must be idling to ensure freshwater circulation throughout the cooling system. Again, this process should be done with the engine in the lowered operating position. Attach a freshwater garden hose to the adaptors and fush the engine for 10 to 15 minutes. Don't walk away—you want to be there to make sure the ear mufs don't fall of the lower unit while the engine is idling.

›› On the water: Clear a fouled intake or water pump: Shift the motor into neutral and engage the neutral safety switch and throttle-up briefly. This procedure will speed up the water flow in the pumping system and can blow out sediments and other small materials that may be impeding cooling water flow and causing overheating.

›› Manually clearing the intake vent on the lower unit is also a simple procedure. Attempt this only when the engine is of and the key removed from the ignition or the battery switch in the of-position.



›› If the pilot hole on back of the engine is either sporadic or plugged, try clearing it by inserting a section of heavy monoflament of 50- to 80-pound test to clear the blockage. If this procedure fails to adequately open the relief line, it can generally be disconnected from the engine's outside casing and cleared from within by fushing the engine again, holding the relief line outside the casing. One note: the pilot hole represents only about 15 percent of the cooling water running through your engine.

›› Periodic inspection of thermostats: Your mechanic or shop manual will advise the correct interval for replacement. But for heavy use in shallow, sediment-laden waters, these devices can be removed and checked. Inspect the gallery the unit is housed in and manually clear any debris. You may have to carefully jimmy the unit out, since they are often stuck in place with a sticky residue. Attach your fushing hose and run the water through theengine with or without the engine running, depending on your engine's design. Before you reinstall the thermostat, you may want to take very fne emery cloth and delicately polish the gallery walls where the thermostat is installed. These simple procedures will further clear and clean the cooling galleries, aiding in the thermostat performance and engine duty life. If in doubt, replace the thermostat; generally around $30 for most manufacturers.

›› Train yourself to record the maintenance schedule. Don't rely on your memory. If your motor is equipped with an hour meter, that's even better. Many newer motors have a computer function, and maintenance intervals, performance records and alarm info can be accessed by a certifed, manufacturer-trained tech. If your boat sits for a prolonged period, hose it up and run it periodically to keep the parts lubed and loose. Fire her up at least once every week or two. Prolonged seasonal storage may require further steps to get and keep your mill in tiptop shape. - FS

First Published Florida Sportsman July 2013

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