The preferred method is to flush with a flush-muff attachment or built-in port. With flush
muffs, run the engine only at idle speed in
neutral for a few minutes while monitoring
it at all times for proper water flow out of
the tell-tale outlet. There are two possible
flushing ports — one on the port side of
the engine midsection, the other on the
front side of the lower cowl. The engine can
be running or stopped; flush for about five
minutes, and ensure the engine drains completely. When not running, the engine can
be flushed in the tilted position, but must
be returned to the vertical position to drain
flow to the intakes. The engine should be run
for five to 10 minutes.
water, and also as a part of preparing the
outboard for storage.
Verado four-stroke outboards: No description of using flush muffs is shown in the
manual, only the engine’s hose-adapter fitting. The description of the procedure is
short, noting only that the engine should be
off and can be either tilted or vertical.
Yamaha gives three choices — with a flush
bag, muffs, or hose-port connector — and
says all three methods work equally well.
Bag and Muffs: Engine should be vertical,
run no more than 800-900 rpm in neutral
for 15 minutes with the prop removed. Be
sure the engine is receiving cooling water (by
checking the overboard indicator). If your
outboard has more than one set of cooling
inlets, a flush bag should be used. Flushing
Port: Engine should not be running; it can be
tilted or vertical. Prop should be removed.
Flush for 10-15 minutes.
For smaller engines ( 2 to 6 hp), use either the
optional flushing plug or a small container
such as a garbage can or tub filled with fresh
water. For larger engines, use the flush port or
a set of flushing muffs. Water pressure should
be set to one-half or more to ensure adequate
John Tiger owned his first outboard at age 7;
since then he has owned more than 60 boats
and outboards. He started outboard racing at
14 and is still active, building racing engines
and rigging performance boats in his shop in
upstate New York.
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