A compressor efficiency or build-up test can be
To the discharge port of the compressor connect
run which is not too difficult. Before the test the
a reservoir or reservoirs whose volume plus the
volume of the connecting line equals 1300 cubic
c r a n k c a s e of a self-lubricated type compressor
i n c h e s (2130 cm 3 ). Run the compressor between
should be properly filled with lubricating oil. An
1700 and 1750 RPM. Elapsed time that the compres-
engine lubricated compressor must be connected
sor takes to build up from 0 to 100 psi (0 to 7/kg/cm2)
to an oil supply line of at least 15 pounds (1.05 kg/
d e p e n d s on the type compressor: Tu-Flo 500, 30
cm) pressure during the test and an oil return line
seconds maximum.
must be installed to keep the crankcase drained.
T h e compressor (when tested) should be tested
During the above test the compressor should be
without a strainer.
checked for oil leakage and noisy operation.
TROUBLESHOOTING
COMPRESSOR FAILS TO MAINTAIN
COMPRESSOR PASSES EXCESSIVE OIL
SUFFICIENT PRESSURE IN THE AIR SYSTEM
Excessive wear.
AND PROBABLE CAUSES
Dirty air strainer. (Improper air strainer mainte-
Dirty intake strainer.
nance.)
Restriction in compressor cylinder head intake or
High inlet vacuum.
discharge cavities or in discharge line.
Small oil return line.
Leaking or broken discharge valves.
Excessive oil pressure.
Excessive wear.
Oil supply or return lines to compressor flooded.
Drive belt slipping.
Defective or worn oil seal rings in end cover.
Inlet valves stuck open.
Piston rings not properly installed.
Worn inlet valves.
Back pressure from engine crankcase.
Excessive system leakage or usage.
COMPRESSOR NOT UNLOADING
NOISY OPERATION
Defective unloader pistons or bores.
Loose drive pulley.
Intake cavity restrictions.
Restrictions in cylinder head or discharge line.
Defective governor.
Worn or burned out bearings.
Unloader line or cavity to governor restricted.
Worn drive coupling.
Unloader mechanism binding or stuck.
Compressor not getting proper lubrication.
Excessive wear.
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