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ing rod bushings. Rod bushings can be inspected
by removing the side place and rod caps. Another
way to check is to remove the head and observe
the piston while rocking the flywheel. The piston
should follow the movement without play (except
at the top and bottom dead center where piston
will appear to hesitate). Inspect the cylinder and
head for carbon build up.
4. Bad main bearings-check for end play by attempt-
ing to move the flywheel in different directions.
Listen and feel for any play, End play on the
crank shaft can usually be eliminated by removing
one of the shims beneath the bearing housing
adjustment plate. A slight drag when turning by
hand is proper.
NOISY MOTOR
Most likely cause is a loose motor pulley, A low
pitched growl could be an indication of low voltage.
If the noise was slight, lubricate motor in accordance
with instructions on nameplate. If noise disappears, the
motor will probably be OK but should be watched more
carefully as its life has been shortened by the dry bearing.
To check bearings, stop the motor and remove the
belt and check for side play in the motor shaft. Also
turn motor by hand. Any side play or noise is an indica-
tion of bad bearings. Replace motor. End play (move-
ment of motor shaft in and out) is common in this type
of motor and not an indication of wear.
NOISE NOT LOCATABLE
The use of a large screwdriver or similar implement is
handy here. Place the pointed end against suspected
areas and the other against the ear. WATCH OUT FOR
THE SPINNING FLYWHEEL AND BELT.
In the 1/2 and 1/4 HP sizes a noise which cannot be
traced to the pump or motor will usually be the check
valve (the larger units do not have a check valve). The
check valve should be disassembled and inspected.
Replace if cleaning does not stop the noise.
Another noise which is not easily traceable is the belt
guard. This can be checked by applying hand pressure to
the outside surfaces at different points.
Intake filter gaskets should not be modified since
they are designed to minimize noise.
WON'T START
If there is no attempt to start, make certain power is
applied and fuses installed, With W240 units, checkout
of electrical power application to the pump motor will
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differ with the operation requirements of each system,
See wiring diagrams. If a voltage tester is available, check
for proper power at the motor terminals. If no power,
trace wiring back towards the source to locate the
problem.
CHECK FIRST AT THE PRESSURE SWITCH
If there is power at the motor terminals but the unit
is making no attempt to start, feel the motor. If hot,
built-in thermal protectors (up to 1 HP only) may be
disconnecting motor. Disconnect power and allow motor
to cool down. If motor now attempts to start, treat as
as described above. If cold, motor is defective and must
be replaced.
If it attempts to start, remove the belt and see if the
motor will start and run by itself. If the motor fails to
run, repair or replace motor. If the motor appears to run
properly with no load, it may have a defective capacitor
or centrifugal switch (single phase models only). With
the belts removed, try turning pump by hand. It should
run freely. If so, the motor is defective or voltages is
not within motor limits. Recheck both voltage and
motor operation and replace motor if voltage is proper.
GOES OUT ON ELECTRICAL OVERLOAD
If this occurs the first time at startup, the motor
wiring or voltage may be wrong. Recheck these and also
confirm that the oil has been added to the compressor.
Check for excessive tank pressure or faulty check valve.
Remove belt and check motor alone. Turn pump by
hand; it should turn freely,
If the motor appears to run properly without the
pump, and the pump turns freely, reconnect the pump
and run with intake plugged (cover with hand). If the
motor and pump now run properly, a low voltage con-
dition probably exists. Take a voltage reading at the
motor terminals while the unit is pumping. Fractional
HP motors will usually "growl" with low voltage, a good
clue to the problem,
An oversized motor pully can also cause electrical
overload. Check the RPM and pully size (see Data Table).
WON'T PUMP AIR
This section is broken up into three categories as
follows:
1. Runs, but tank shows no build up
2. Builds up, but not completely or takes excessive
time
3. Pump slows, stalls, or goes out on overload
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