TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Charge-Air Cooler (CAC) (010-027)
Section 10 - Air Intake System - Group 10
Page 10-25
If the pressure decay is caused by a leaky connection,
repair the connection and repeat the test. If the leak is
within the CAC, repeat the test to verify the accuracy of the
pressure decay measurement. Similar pressure decay read-
ings must be obtained at least three consecutive tests
before the reading can be considered accurate.
If the pressure drop is greater than 49 kPa [7 psi] in 15
seconds, the CAC must be replaced.
Refer to the OEM service manual for replacement instruc-
tions.
NOTE: Charge air coolers (CAC) are not designed to be
100-percent leak-free. If the pressure decay is less than 49
kPa [7 psi] in 15 seconds, then the CAC does not need to
be replaced.
CAUTION
Debris trapped in the charge air cooler, if not cleaned,
will cause internal engine damage.
The charge air cooler must be cleaned following any turbo-
charger or air cleaner malfunction.
Temperature Differential Test (010-027-049)
Inspect the charge air cooler (CAC) fins for obstructions to
airflow. Remove obstructions such as a winterfront or de-
bris. Manually lock shutters in the open position, if
equipped.
Lock the fan drive in the ON mode to prevent erratic test
results. This can be done by installing a jumper wire across
the temperature switch.
L-1149
