4 ENGIN E SY M PTOMS DIAGNOSTICS 109
Coolant in Lube Oil
Symptom
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 overfille d.
Cause
• Accessory leak (water cooled air compressor)
• Injector sleeve leak
• Cylinder head cup plug failure
• Crevice seal (liner O-ring)
• Cylinder head gasket leak
• Front cover gasket damage
• Front cover, cylinder head or crankcase porosity
Tools
• Radiator pressure testing kit
• Plastic surge tank cap adapter
• Cylinder head test plate
• Water supply housing pressure adapter
• Thermostat opening pressure adapter (cylinder
head)
• Straightedge
• Feeler gauge
Coolant System Inspection
Procedure
1. Check oil level to verify oil contamination
complaint.
• The presence of coolant in the oil will
generally give the oil a dark-gray or black
sludgy appearance.
• If coolant in the oil is no t v erified, an oil sample
can be taken for analysis.
2. When oil contamination is verified, plug in cylinder
block heater to warm coolant.
3. Istheengineequippedwithanaircompressor?
• Ifyes,dostep4.
• If no, do step 8.
Figure 123 Air compressor oil drain-back hose
4. Remove air compressor oil drain-back hose from
the bottom of compressor.
5. Install radiator pressure tes ter with the
appropriate adapter.
WARNING: To avoid serious personal
injury, possible death and damage to the
engine:
• Always allow the engine to cool for 15
minutes.
• Wrap a thick cloth around the cap.
• Loosen cap slowly a quarter to half turn.
• Pause for a moment to avoid water or
steam scalding.
• Continue to turn the cap and remove.
• Never add cold coolant to a hot engine.
This can result in a cracked cylinder head
or crankcase.
• Never use water as a coolant substitute.
6. Pressurizethecoolingsystemto96kPa(14psi).
7. Look for coolant leaking from the air compressor
oil drain-back port.
• If coolant is leaking from air compressor,
repair or replace air compressor.
• If coolant is not leaking from the air
compressor oil drain-ba ck port, do step 8.
8. Drain engine oil and remove the oil filter.
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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