128 4 ENGINE SYMPTOMS DIAGNOSTICS
Low Oil Pressure
Symptom
Low oil pressure can cause any or a ll of the following :
•RedENGINElamp
• DTC 313 – Engine oil pressure below warning
level
• DTC 314 – Engine oil pressure below critical level
• Engine knock
• Engine hard start or no start condition
• Engine loss of power
• DTC 335 – ICP unable to build pressure during
cranking
• DTC 333 – Injection control pressure above/below
desired level
Cause
• Instrument panel gauge error
• Low oil level: oil leak, oil consumption or incorrect
servicing
• High oil leve l: incorrect servicing, fuel in oil o r
coolant in oil
• Incorrect oil viscosity
• Incorrect EOP sensor
• Stuck oil p ressure regulator
• Scored/damaged oil pump
• EOP sensor biased
• Broken, missing or loose piston cooling tube(s)
• Missing, damaged or worn bearing inserts or
camshaft bushings
• Aeration (cracked pickup tube or pickup tube
gasket)
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Gauge bar tool
• Air Regulator
• Shut-off valve
Oil Inspection
WARNING: To avoid serious personal injury,
possible death or damage to the engine or
vehicle, read all safety instructions in the “Safety
Information” section of this manual.
1. Park vehicle on level ground.
2. Check oil level with oil level ga u ge .
NOTE: Never check the oil level when the e ng ine
is running or immediately after the engine is shut
down; the re ad ing will be ina ccurate. Allow 15
minute drain down time, before checking oil level.
NOTE: If the oil level is t oo low, the fuel injectors
will not work correctly. If the oil level is above the
operating range, the engine has been incorrectly
serviced, fuel is in the oil, or coolant is in the oil.
• Engine oil level will vary depending on
temperature of engine
• If oil level is low, fill to the correct level and
retest.
• If oil level is at the correct level and not
contaminated, do step 4.
3. Inspect oil for th ickening and odor.
NOTE: When the crankcase lube oil is
contaminated with coolant, the oil will have a
dark-gray or black sludgy appearance. The
crankcase may also be overfilled.
• If oil is contaminated, go to “Fuel in Lube Oil”
(page 124) or “Coolant in Lube Oil” (page 109)
test procedures located in this section.
• If oil level is at the correct level and not
contaminated, do step 4.
4. Measure pressure at low and hig h idle. The
engine must be at operating temperature.
• If oil pressure does not read within the
specification listed in Appendix A in this
Manual, go to “Oil Pressure Regulator
Inspection” (page 129) in this section.
• If oil pressure reads within specification
listed in Appendix A in this Manual, compare
mechanical gauge readings with instrument
panel gauge and Engine Oil Pressure (EOP)
value on the Electronic Service Tool (EST).
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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