Evinrude 4906B 4HP 1969, Руководство пользователя

Страница: 170 / 422

Checking Compression
4- Remove the spark plug wires.
ALWAYS grasp the molded cap and pull it
loose with a twisting motion to prevent
damage to the connection. Remove the
spark plugs and keep them in
ORDER
by
cylinder for evaluation later. Ground the
spark plug leads to the engine to render the
ignition
system inoperative while
performing the compression check.
Insert a compression gauge into the
No.1, top, spark plug opening. Crank the
engine with the starter, or pull on the
starter cord, through at least
4-
complete
piston strokes with the throttle at the wide-
open position, or until the highest possible
reading is observed on the gauge. Record
the reading.
Repea t the test and record the compres-
sion for each cylinder. A variation between
cylinders is far more important than the
actual readings. A variation of more than 5
psi between cylinders indicates the lower
compression cylinder may be defective. The
problem may be worn, broken, or sticking
piston rings, scored pistons or worn cylin-
ders. These problems may only be deter-
mined after the head has been removed.
Removing the head on an outboard engine is
not that big a deal, and may save many
hours of frustration and the cost of
purchasing unnecessary parts to correct a
faul ty condition.
Condenser
In simple terms, a condenser is composed
of two sheets of tin or aluminum foil laid
TROUBLESHOOTING 5-11
ALTERNATE LAYERS OF
INSULATION -- WAXED PAPER
-
ALTERNATE LAYERS OF FOIL
TI N OR ALUM I NUH
FOIL
\
INSULATION
Rough sketch to illustrate how the waxed paper,
aluminum [oil, and insulation are rolled in
a
typical
condenser.
one on top of the other, but separated by a
sheet of insulating 'material such as waxed
paper, etc. The sheets are rolled into a
cylinder to conserve space and then inserted
into a metal case for protection and to
permit easy assembly.
The purpose of the condenser is to ab-
sorb or store the secondary current built up
in the primary winding at the instant the
breaker points are separated. By absorbing
or stor ing this current, the condenser pre-
vents excessive arcing and the useful life of
the breaker points is extended. The conden-
ser also gives added force to the charge
produced in the secondary winding as the
condenser discharges.
Modern condensers seldom cause prob-
lems, therefore, it is not necessary to install
a new one each time the points are replac-
ed. However, if the points show evidence of
arcing, the condenser may be at fault and
should be replaced. A faulty condenser may
not be detected without the use of special
test equipment. The modest cost of a new
condenser justifies its purchase and installa-
tion to eliminate this item as a source of
trouble.
Proper hookup to test a condenser.