5. Inspection and servicing of basic engine parts
181
5.2.1 Inspecting the cylinder head
The cylinder head is subjected to very severe
operating conditions with repeated high pressure,
high temperature and cooling. Thoroughly remove
all the carbon and dirt after disassembly and
carefully inspect all parts.
(1) Distortion of the combustion surface
Carefully check for cylinder head distortion as
this leads to gasket damage and compression
leaks.
1) Clean the cylinder head surface.
2) Place a straight-edge along each of the four
sides and each diagonal. Measure the
clearance between the straight-edge and
combustion surface with a feeler gauge.
(2) Checking for cracks in the combustion
surface
Remove the fuel injection nozzle, intake and
exhaust valve and clean the combustion
surface. Check for discoloration or distortion
and conduct a color check test to check for
any cracks.
(3) Checking the intake and exhaust valve
seats
Check the surface and width of the valve
seats.
If they are too wide, or if the surfaces are
rough, correct to the following standards:
mm
Standard Limit
Cylinder head
distortion
0.05 or less 0.15
Seat angle
Intake 120°
Exhaust 90°
Standard Limit
Seat width
Intake 1.07-1.24 1.74
Exhaust 1.24-1.45 1.94
007087-00X
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007358-00X
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