230 6 PERFORMANCE DIAGNOSTICS
Figure 300 Air filter housing tap
2. Remove air intake restriction indicator or remove
line to instrument panel restriction gauge from air
filter hous ing.
3. Attach test line to tap for a ir filter housing.
WARNING: To avoid serious personal injury,
possible death or damage to the engine or vehicle
– comply with the following:
When routing test line, do not crimp the line, run
the line too close to moving parts , or let the line
touch hot engine surfaces.
4. Connect line to magnehelic gauge or manometer.
WARNING: To avoid serious personal injury,
possible death or damage to the engine or vehicle
– comply with the following:
When running the engine in the service bay, make
sure the parking brake is set, the transmission is
in neutra l, and the wheels are blocked.
5. Run engine at high idle, no load.
6. Record reading on Diagnostic Form.
• If restriction is more than 3.13 kPa (12.5 in
H
2
O), replace air filter element.
• If restriction is more than 3.13 kPa (12.5 in
H
2
O),andanewfilter is in place, check for
obstruction s in air inlet.
• If restriction is less than 3.13 kPa (12.5 in
H
2
O), continue with Performance Diagnostics.
NOTE: An equivalent test, using the instrument
mounted restriction indicator, can only be done
while operating the engine at full load and rated
horsepower. The true maximum air filter restriction
forthistestis6.22kPa(25inH
2
O).
Possible Caus es
• Clogged air filter element (dust, dirt, or debris)
•Snowinairfilter inlet
•Iceinairfilter inlet
• Plastic ba gs or other fore ign material in air filter
inlet
• Collapsed air filter
• On engines recently repaired, rags or cap plugs
may have been left in the intake system.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any proced ures.
Follow all warnings, cautions, and notes.
©August 2008 Navistar, Inc.
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