Service Manual

ISB, ISBe and QSB (Common Rail [...] Charge-Air Cooler (CAC)
Section 10 - Air Intake System - Group 10 Page 10-29
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Temperature Differential Test
Inspect the charge air cooler fins for obstructions to
airflow. Remove obstructions such as a winterfront or
debris. 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.
Install the thermocouple bead probe Part Number
3154498.
Connect the digital multimeter, Part Number 3164488,
and the temperature adaptor, Part Number 3164499 to
the thermocouple bead probe to read intake air
temperature.
Another alternative would be to use the monitor mode on
the INSITE™ service tool.
Install another thermocouple at the air cleaner inlet to
measure ambient air temperature.
Perform a road test with the engine at peak power and a
vehicle speed of 48 km/h [30 mph] or greater.
Record the intake manifold temperature and the ambient
air temperature.
Calculate the differential temperature:
Intake manifold temperature - ambient air temperature =
differential temperature.
• Differential temperature, delta T = 21°C [38°F].
If the temperature differential is greater than the
specifications, check the charge air cooler for dirt and
debris on the fins and clean as necessary. If the problem
still exists, check the charge air cooler for debris in the
fins or between the charge air cooler and radiator.
Confirm full-fan engagement.