Change Engine Oil
If your new four-stroke has been broken in correctly
(according to manufacturer’s recommendations) and operat-
ed for a few months under normal bass fishing conditions,
the first maintenance usually occurs at the 20-hour mark.
At that time, the engine oil and oil filter should be
changed. Only use factory-recommended parts and lubri-
cants. Although four-stroke motors perform similar to, say,
an automobile, their needs are drastically different. For
example, oil must be able to withstand extended high RPM.
Changing oil is simple. A drain screw is located on the
lower gear case. A special wrench may be needed for the oil
filter located beneath the cowling, but it, too, can be easily
removed and replaced. Don’t over-tighten when you replace
it, and refill with the appropriate amount of oil.
Inspecting the fuel filter.
1-Year Maintenance
Replacing the gear oil.
Change Gear Oil
Along with an engine oil change, owners should also
change gear oil at 20 hours. The drain and vent screws for
this may be located on the lower unit, or possibly behind the
prop. In any case, both must be removed to allow all the gear
oil to drain. Check the oil for any discoloration (milky means
water has entered the gear case) or metal pieces. The drain
screw is also magnetic; check it for shavings that could indi-
cate a gear problem.
When refilling, gear oil must be pumped back in through
the drain hole until it comes out the vent. Wait five minutes
and pump a little more in to ensure it’s filled to capacity.
Change Fuel Filters
Fuel filters require initial 20-hour maintenance as well.
Large four-stroke outboards include a fuel/water separator
filter in the bilge area of the boat. This can be easily changed
and should be during this initial service. Other filters vary by
manufacturer. For instance, Yamaha recommends an author-
ized dealer check and change other fuel filters (located on
the motor) at 20 hours, then again every 100 hours. The
Mercury Verado also includes an additional pressurized filter
that should be serviced by a dealer, but not until 300 hours.
WINTER 2019 I FLWFISHING.COM
Usually, after one year or 100 hours it’s time for the out-
board’s second scheduled maintenance. At this point, engine
oil and filter, gear oil, and fuel filters should be changed
again. In addition, the water pump should be inspected, and
the impeller should be changed by the dealer (while the
impeller may be in good shape, simple pump inspection
requires substantial labor cost, so the part is changed for
preventive purposes). In addition, spark plugs should be
inspected and changed as needed. Good plugs will have a
bronze coloration and sharp edges.
Additionally, some dealers such as Toho Marine will per-
form further tests as part of their regular 100-hour service,
including a computer diagnostic to check for codes that
might indicate operating errors, and make sure the motor is
firing efficiently. Further service also includes a compression
check to ensure there’s no advanced carbon build-up or ring
problems within the motor.
This same 100-hour service should be performed annual-
ly with normal usage. As discussed, check your user manual
for recommended 300-hour inspections and filter changes,
as well as belt service at 1,000 hours.
MORE ADVICE
A number of other service items can reduce
headaches on the water:
1. Use fuel additives whenever possible, and stabi-
lizer when needed, to reduce carbon build-up and fight
the problems created by ethanol.
2. Fight corrosion on battery terminals with terminal
cleaner.
3. Spray down the cowling seal with a silicone spray
to keep it supple and watertight.
4. Visually inspect the power trim and tilt rams and
seals for any leaks, and retract the rams all the way in
during extended periods of non-use.
5. Each spring, inspect the cooling system outflow
hole on the side of the motor to ensure it’s not clogged.
6. Finally, the best tip for any of today’s outboards:
Buy gas at a busy station, and do not allow it to sit in
your tank for more than a few months. ■
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