TROUBLESHOOTING GUIDE
MAINTENANCE /
REP
AIR
TROUBLESHOOTING
OPERA
TION
ASSEMBL
Y
/
INST
ALLA
TION
SAFETY
/
SPECIFICA
TIONS
GETTING
ST
ARTED
12
OPERA
TION
SYMPTOM
POSSIBLE CAUSE(S)
CORRECTIVE ACTION
Low discharge pressure
1. Air demand exceeds pump capacity
1. Reduce air demand or use a compressor with more
capacity.
2. Air leaks
2. Listen for escaping air. Apply soap solution to all
fittings and connections. Bubbles will appear at
points of leakage.Tighten or replace leaking fittings or
connections.
3. Restricted air intake
3. Clean the air filter element.
4. Blown gaskets
4. Replace any gaskets proven faulty on inspection.
5. Leaking or damaged valves
5. Remove head and inspect for valve breakage,
misaligned valves, damaged valve seats, etc. Replace
defective parts and reassemble.
Install a new head gasket
each time the head is removed
Pump overheating causes air
filter to melt
1. Insulating gasket between filter and
head is missing
1. Install gasket.
2. Broken valves/blown gasket
2. Replace valves or install new gasket.
Excessive noise (knocking)
1. Loose motor or compressor pulley
1. Loose motor or compressor pulleys are a very common
cause of compressors knocking. Tighten pulley clamp
bolts and set-screws.
2. Lack of oil in crankcase
2. Check for proper oil level; if low, check for possible
damage to bearings. Dirty oil can cause excessive
wear.
3. Worn connecting rod
3. Replace connecting rod. Maintain oil level and change
oil more frequently.
4. Worn piston pin bores
4. Remove piston assemblies from the compressor and
inspect for excess wear. Replace excessively worn
piston pin or pistons, as required. Maintain oil level and
change oil more frequently.
5. Piston hitting the valve plate
5. Remove the compressor head and valve plate and
inspect for carbon deposits or other foreign matter on
top of piston. Replace head and valve plate using new
gasket. See Lubrication section for recommended oil
6. Noisy check valve in compressor
system
6. Replace.
Do not disassemble check valve
with air pressure in tank
Large quantity of oil in the
discharge air
NOTE:
In an oil lubricated
compressor there will always be
a small amount of oil in the air
stream.
1. Worn piston rings
1. Replace with new rings. Maintain oil level and change
oil more frequently.
2. Compressor air intake restricted
2. Clean filter. Check for other restrictions in the intake
system.
3. Excessive oil in compressor
3. Drain down to full level.
4. Wrong oil viscosity
4. Use Mobil 1
®
10W-30
Water in discharge air/tank
1. Normal operation. The amount of water
increases with humid weather
1. Drain tank more often. At least daily.
2. Add a filter to reduce the amount of water in the air line.
Motor hums and runs slowly or
not at all
1. Use of extension cord
1. Do not use an extension cord. Use longer air hose with
larger diameter.
2. Malfunctioning check valve or unloader
valve
2. Replace check valve, unloader valve or pressure
switch.
Do not disassemble check valve
with air pressure in tank
3. Low voltage
3. Check with volt meter, check reset switch on motor. If
reset switch trips repeatedly, find and correct the cause.
See next item.
4. Malfunctioning pressure switch -
contacts will not close
4. Repair or replace pressure switch.
