5
Single-Stage Compressor Pumps
www.chpower.com
Symptom
Possible Cause(s)
Corrective Action
Low discharge pressure
1 . Air leaks
1 . 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
2 . Slipping belts
2 . Loosen motor clamping bolts and move the motor in
a direction away from the compressor, being sure that
the motor pulley is perfectly aligned with the flywheel .
Tighten motor clamping bolts . The belt should deflect
about 1/2 inch under 5-lbs of pressure . Do not “roll” belts
over pulleys
3 . Air demand exceeds pump
capacity
3 . Reduce air demand or use a compressor with more
capacity
4 . Blown gaskets
4 . Replace any gaskets proven faulty on inspection
5 . Leaking 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
6 . Restricted air intake
6 . Clean the air filter element
7 . Low compression
7 . Low pressure can be due to worn rings and cylinder walls .
Correction is made by replacing the rings, cylinders, and
pistons as required
Pump overheating causes
air filter to melt
1 . Broken valves/blown gasket
1 . Replace valve 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 . Worn bearings
5 . Replace worn bearings and change oil
6 . Piston hitting the valve plate
6 . 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
7 . Noisy check valve in compressor
system
7 . Replace
Large quantity of oil in
the discharge air
nOTe:
Oil lubricated
compressors will always
have 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 .
Troubleshooting Chart