18
Troubleshooting
Problem
Possible Cause
Solution
The discharge pressure
is low.
□
The air demand exceeds the pump
capacity.
□
Reduce the air demand or use a compressor with more capacity.
□
The air intake is restricted.
□
Clean or replace the air filter element.
□
There are air leaks in the fittings,
tubing on the compressor, or the
plumbing outside the unit.
□
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. Use pipe thread sealant.
□
There are blown gaskets.
□
Replace any gaskets proven faulty on inspection.
□
There are leaking or damaged valves.
□
Remove the 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.
The air compressor unit is
making excessive noise (a
knocking sound).
□
The motor pulley or the flywheel is
loose.
□
Tighten the pulley / flywheel clamp bolts and the setscrews.
□
The fasteners on the pump or the
motor are loose.
□
Tighten the fasteners.
□
There is no oil in the crankcase.
□
Check for proper oil level; if the oil level is low, check for possible
damage to the bearings. Dirty oil can cause excessive wear.
□
The connecting rod is worn.
□
Replace the connecting rod. Maintain the oil level and change the oil
more frequently.
□
The piston pin bores are worn.
□
Remove the piston assemblies from the compressor and inspect for
excess wear. Replace the excessively worn piston pin or pistons, as
required. Maintain the oil level and change the oil more frequently.
□
The piston is hitting the valve plate.
□
Remove the compressor head and the valve plate and inspect for
carbon deposits or other foreign matter on the top of the piston.
Replace the head and the valve plate using the new gasket. See the
Lubrication section for the recommended oil type.
□
There is a noisy check valve in the
compressor system.
□
Replace the check valve. Do not disassemble the check valve with
air pressure in the tank.
There is a large quantity of
oil in the discharge air.
In an oil lubricated
compressor there will
always be a small amount
of oil in the air stream.
□
The piston rings are worn.
□
Replace with new rings. Maintain the oil level and change the oil
more frequently.
□
The compressor’s air intake is
restricted.
□
Clean or replace the filter. Check for other restrictions in the intake
system.
□
There is excessive oil in the compres-
sor.
□
Drain oil down to the correct full level.
□
The oil viscosity is wrong.
□
Only use Mobil 1® 10W-30 or SAE 30 industrial grade compressor
oil.
There is water in the
discharge air / tank.
□
This is normal during operation.
The amount of water increases with
humid weather.
□
Drain the tank more often. At least daily during use.
□
Add a filter to reduce the amount of water in the air line.
The pressure switch does
not release air when the
unit shuts off.
□
The unloader valve on the pressure
switch is malfunctioning.
□
The hole to the unloader line on the
check valve is plugged.
□
Replace the unloader valve if it does not release the pressure for
a short period of time when the unit shuts off. Do not disassemble
the check valve with air pressure in the tank.
□
Check for debris in the unloader line or check the valve that could
block air flow. Do not disassemble the exhaust tube or unloader
tube with air pressure in the tank.
