Observable Diagnostics and Tests
04
150
17
DPSG,RG40854,281 –19–27NOV00–1/2
Check for Head Gasket Failures
RG8429 –UN–19MAY98
Head Gasket
A—Combustion Seals B—Gasket Body C—Front of Engine
(Flanges)
Head gasket failures generally fall into three
categories:
• Combustion seal failures
• Coolant seal failures
• Oil seal failures
Combustion seal failures occur when combustion
gases escape between cylinder head and head gasket
combustion flange, or between combustion flange and
cylinder liner. Leaking combustion gases may vent to
an adjacent cylinder, to a coolant or oil passage, or
externally.
Coolant or oil seal failures occur when oil or coolant
escapes between cylinder head and gasket body, or
between cylinder block and gasket body. The oil or
coolant may leak to an adjacent coolant or oil
passage, or externally. Since oil and coolant passages
are primarily on right hand (camshaft) side of the
engine, fluid leaks are most likely to occur in that area.
Follow these diagnostic procedures when a head
gasket joint failure occurs, or is suspected.
1. Start and warm up engine if it can be safely
operated. Examine all potential leakage areas again
as outlined previously. Using appropriate test and
measurement equipment, check the following:
• White smoke, excessive raw fuel, or moisture in
exhaust system.
• Rough, irregular exhaust sound, or misfiring.
• Air bubbles, gas trapped in radiator/overflow tank.
• Loss of coolant from overflow.
• Excessive cooling system pressure.
• Coolant overheating.
• Low coolant flow.
• Loss of cab heating (air lock)
2. Shut engine down. Recheck crankcase, radiator,
and overflow tank for any significant differences in
fluid levels, viscosity, or appearance.
3. Compare your observations from above steps with
the diagnostic charts on the following pages. If
diagnostic evaluations provide conclusive evidence
of combustion gas, coolant, or oil leakage from
head gasket joint, the cylinder head must be
removed for inspection and repair of gasket joint
components.
COMBUSTION SEAL LEAKAGE
Symptoms:
• Exhaust from head gasket crevice.
• Air bubbles in radiator/overflow tank.
• Coolant discharge from overflow tube.
CTM100 (06APR04)
04-150-17
P
OWER
T
ECH
10.5 L & 12.5 L Diesel Engines
040604
PN=365
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