27
A-9
Symptom:
What it may indicate:
What you should do:
8.0 Oil in ping tank
or compressor dis-
charge aftercooler.
Air brake charging system is functioning
normally.
Air dryers remove water and oil from
the air brake charging system. A small
amount of oil is normal. Check that regular
maintenance is being performed and that
the amount of oil in the air tanks (reservoirs)
is within the acceptable range shown by the
BASIC
™
test (see also column 5 of Table
A on page A-3). Replace the air dryer
cartridge as needed and return the vehicle
to service.
7.0 Oil present
at air dryer
cartridge during
maintenance.
A problem with engine or other engine
accessory.
See engine service manual.
6.0 Excessive oil
consumption in
engine.
Air brake charging system is functioning
normally.
Follow vehicle O.E. maintenance
recommendation for these components.
(a) Air brake charging system
functioning normally.
(b) Air brake system leakage.
(c) Compressor may be undersized for
the application.
(d) Compressor unloader mechanism
malfunction.
(e) Damaged compressor head
gasket.
Using dash gauges, verify that the
compressor builds air system pressure
from 85–100 psi in 40 seconds or less with
engine at full governed rpm. Return the
vehicle to service.
Go to Test 2 on page A-14.
See Table A, column 1, on page A-3 for
some typical compressor applications. If the
compressor is "too small" for the vehicle's
role, for example, where a vehicle's use has
changed, then upgrade the compressor.
Note: The costs incurred (e.g. installing
a larger capacity compressor, etc.) are
not covered under original compressor
warranty.
Go to Test 6 on page A-15.
An air leak at the head gasket may
indicate a downstream restriction such as a
freeze-up or carbon blockage and/or could
indicate a defective or missing safety valve.
Find blockage (go to 9.0(f) for details)
and then replace the compressor. Do not
reuse the safety valve without testing. See
Symptom 12.0(a).
9.0 Air brake
charging system
seems slow to
build pressure.
The engine
service
manual
has more
information.
Oil shown
leaking
from an
air dryer
cartridge.
