Engine System Operation and Tests
DIAGNOSING HEAD GASKET JOINT
NOTE: Booklet DB1119--CYLINDER HEAD GASKET
FAILURES for 6466 and 6076 Engines can be
used as a guide for diagnosing head gasket
failures on POWERTECH 4.5 L and 6.8 L
Engines. However, use specifications provided in
Head gasket failures generally fall into three categories:
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
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
A--Combustion Sealing Area
externally. Since oil and coolant passages are primarily on
B--Oil Sealing Areas
right hand (camshaft) side of engine, fluid leaks are most
C--Coolant Sealing Areas
likely to occur in that area.
Follow these diagnostic procedures when a head gasket
joint failure occurs, or is suspected.
1. Before starting or disassembling engine, conduct a
visual inspection of machine, and note any of the
Oil or coolant in head gasket seam, or on adjacent
surfaces. Especially right rear corner of gasket joint.
Displacement of gasket from normal position.
Discoloration or soot from combustion gas leakage.
Leaking radiator, overflow tank, or hoses.
Leaking coolant from water pump weep hole.
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