YOUR SENSE OF HEARING
Ignoring Whining Now Could Make You Cry Later
SOME PROBLEM NOISES ARE OBVIOUS. Some are not. Get into the habit of regularly listening to critical components such as the fresh- and raw-water pumps, alternator,
transmission, injector pump (if you have a diesel),
and any other convenient spots. You’ll then have an
idea of what’s normal. You can use a long screwdriver
with plastic handle to listen. Touch the blade to the
part and put your ear to the round end of the plastic
handle. Far better, buy a mechanic’s stethoscope.
They usually cost less than $20, and are much more
sensitive and safer to use. Keep well clear of the pulleys and belts when you do this.
A mechanic’s stethoscope can be used to
detect unusual noises
in engine components.
Here, Tom Neale
listens to the turbo.
MAIN PHOTO: SCOTT SOMMERLATTE; INSET, MEL NEALE
No matter what
size boat you
have — runabout
to cruiser —
there are often
■ A gravelly noise from a component with bearings
can indicate that the bearings are about to fail. The
alternator and fresh-water recirculating pump are
prime suspects when you hear this. A belt that’s too
tight could hasten either of these failures.
■ Change in tilt-lift motor noise on an outboard
could be a precursor to pump failure or air in the
tilt motor fluid. It could also indicate drop in voltage that could indicate fault in the charging system,
corroding connections, or wiring. Note: It’s normal
for most tilt motors to have two different levels
of sounds as the function shifts from power trim
adjustment to full tilt.
■ Variation in the engine noise, called “hunting,” could indicate impurities in the
fuel, an air leak in the suction line, a clogging filter, a failing fuel pump, or a failing
■ A “thunk” when you push the starting button means problems, even if your engine
then seems to start normally. The “thunk” could be caused by a hydraulic lock resulting
from water standing on top of a piston. If you hear a lighter “clunk” in the starter, it may
be a bad solenoid, engagement gear, or starter.
■ A squealing noise could indicate a loose V-belt, but it could also be a clue that one of the
components it is turning, such as the alternator or fresh-water recirculating pump, is freezing up. Bad bearings could be causing this in both components. Overload or deteriorating
internal parts could cause this in the alternator.
■ Unusual cracking or creaking sounds when hitting seas, running at speed, or otherwise stressing the hull could indicate delamination, structural bonds failing between
bulkheads or supports, impending transom detachment, or other serious problems.
■ The bilge pump running more often than usual means you should start looking for a
leak. Some less obvious sources of water in the bilge include the propeller shaft seal, the
freshwater system, the cooling system, the pop-off valve in the hot water heater, and the
hoses on the engine.
■ Unusual noises in the transmission usually signal a problem developing that could
require professional help very soon.