Chapter 2 Basic Engine
4. Cylinder Head
.4LHA Ser
4-1
Inspecting
the
cylinder
head
The cylineder head is subjected to 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.
4-1.1
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 di-
agonal.
Measure the clearance between the straight-edge
and combustion surface
with
a feeler gauge.
Measurement procedure
Straight-edge
Feeler
gauge
mm(in.)
StandardWear
limit
Cylinder
head
distortion
0.05 or less
(0.002)
0.2(0.0079)
4-1.2 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.
Standard dimension
Intake
valve seat
Exhaust
valve seat
5]
0» -
c
IS ~
1
<i=dH>
^-120°
mm(in.
4LHA-HTE/HTP
4LHA-DTE/DTF
4LHA-STE/STP
Valve
seat
Intake
Di
42.5(1.67)
45.5(1.79)
Valve
seat
Exhaust
D2
37.0 (1.46)
39.0 (1.54)
Valve
Intake
di
43.5 (1.71)
46.0 (2.56)
Valve
Exhaust
d2
37.5(1.48) 39.5 (1.56)
Length of
valve
Intake
Lt 121.0(4.76) 121.5(4.78)
Length of
valve
Exhaust
L2
121.0(4.76) 122.0 (4.80)
4-1.3 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:
Seat
angle
Intake
Exhaust
120*
90*
mm
Seat
width
Standard
Wear
limit
Intake
All
1.38-1.62
2.12
Exhaust
STE/DTE/STP/DTP
2.015-2.227 2.73
Exhaust
HTE/HTP
1.24 1.80
2-15
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