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Turn
off your engine and inspect all wiring and connections. Make sure your
battery terminals and ground points are tight and clean. Check the alternator
belt; it should have no more than 1⁄2 inch of play midway between
the two pulleys. If it still sags after tightening, or if you notice excessive
wear, replace it.
Next
turn on the ignition switch but do not start the engine. Check your battery-voltage
meter; it should read between 12 and 13 volts. If it reads lower, something
is draining it. Check for an open circuit by using your multimeter to
get a reading between the alternator’s positive terminal and ground.
The voltage at the alternator should be the same as at the battery. If
it’s not, that’s a strong indication that something is wrong
with the alternator.
Now
start your engine and check the voltage between the alternator output
and ground; it should be between 13 and 14 volts. If it isn’t, have
your alternator checked by a qualified technician.
I’m
new to outboards, and the larger boat I just bought has a tender with
a two-stroke 40-hp engine. How does the cooling system work, and what
kind of maintenance is required? E.M., via e-mail
The
outboard’s cooling system transfers engine heat directly to the
virtually unlimited supply of relatively cool water in which it operates.
It does this using an engine-driven water pump to pull water from an intake
on the bottom of the lower unit, circulate it through all internal powerhead
cavities, and pump it back out of the engine. In most outboards, this
pump is located inside the intermediate unit, just above the large anti-cavitation
plate.
At idle
speed most of the cooling water exits through a bypass or (sometimes known
as a telltale or “pee hole”) on the underside of the powerhead.
Water flowing from this port indicates that the cooling system is operating
correctly. At anything above idle, most of the cooling water exits through
the propeller since there is less backpressure here underway. The main
advantage of this system is simplicity. Other than the water pump, the
only other cooling system component of note is a thermostat for each cylinder
bank that restricts the flow of coolant to speed warm-ups and helps maintain
proper operating temperature.
The
maintenance required by an outboard cooling system depends on the water
it’s operated in. Freshwater operation typically provides years
of trouble-free service with little maintenance; saltwater less so. In
either case you need to be on the lookout for exterior corrosion and the
buildup of scale in internal passages that will inhibit the transfer of
heat and restrict cooling water flow. Flushing the engine with fresh water
after each use, or at least on a regular basis, is a good way to minimize
internal corrosion. Exterior corrosion can be combated by immediately
touching up any damaged paint.
In addition,
the raw-water pump impeller can be damaged if run dry or when sand or
grit is picked up by the pump and sucked into the system, usually when
the engine is run in shallow water. A reduced flow of water from the telltale
is an indication of a worn impeller. Some outboard owners tend to change
their impellers every season as a preventive measure.
Need
help with a maintenance problem? Write to Maintenance Q & A, Power
& Motoryacht, 260 Madison Ave., 8th Fl., New York, NY 10016. Fax:
(917) 256-2282. e-mail: kkreisler@primediasi.com. No phone calls, please.
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