TM 5-2420-230-24-2
Air Intake Restriction (010-031)
B3.9 and B5.9 Series Engines
Page 10-26
Section 10 - Air Intake System - Group 10
Fluke Digital Thermometer, Part No. 3822666
Install fluke digital thermometer, Part No. 3822666, and
thermocouple wire kit, Part No. 3822988, into the intake
manifold at the 1/8-inch NPT tap near the air horn con-
nection with the intake manifold.
Another alternative would be to use the monitor mode on
the INSITETM service tool.
Install another thermocouple at the air cleaner inlet to mea-
sure ambient air temperature.
Perform a road test with the engine at peak power and a
vehicle speed of 48 kph [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.
Maximum differential temperature = 28C [82F].
If the temperature differential is greater than the specifi-
cations, check the charge air cooler (CAC) for dirt and
debris on the fins and clean as necessary. If the problem
still exists, check the charge air cooler (CAC) for debris in
the fins or between the charge air cooler (CAC) and radiator.
Confirm full-fan engagement.
Air Intake Restriction (010-031)
General Information
Diagnosing Air System Malfunctions
The correct amount of clean air to the cylinders is required
for good performance. As discussed earlier in Airflow Sys-
tem, ingested dust and dirt will damage the engine cylin-
ders. Dust and dirt can also damage the valve stems and
guides, as well as wear down the turbocharger compressor
vanes affecting efficiency. Larger debris can damage the
blades of the turbocharger.
L-1150
