Charge Air Cooler (CAC) - Pressure Testing (10-07)
Section 10 - Air Intake System - Group 10
B Series Shop Manual
3824556 Test Kit
Install a cap over the outlet side of the CAC. Install a
pressure gauge, air supply, and air pressure regulator to
the inlet side of the cooler.
Warning: To prevent possible injury if either plug blows
off during the test, secure safety chains on the test plugs
to any convenient capscrew on the radiator assembly.
This test must be performed with securely fastened safety
Apply 207 kPa [30 psi] of air pressure to the cooler. Close
the air pressure regulator.
Monitor the pressure gauge and determine the rate of
pressure decay with a stop watch.
If the pressure decay is 49 kPa [7 psi] or less in 15
seconds, the cooler is okay. If the pressure drop is greater
than 49 kPa [7 psi] in 15 seconds, check all connections
Determine if pressure decay is caused by a leak in the
CAC or from a leaky connection. Use a spray bottle filled
with soapy water applied to all hose connections, and
watch for bubbles to appear at the location of the leak.
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 de-
cay readings 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 manufacturer's repair manual for repalce-
NOTE: Charge air coolers are not designed to be 100% 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.