MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
126
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
Fig. 4-1-19 Inspection for Cylinder Head Bolt
Fig. 4-1-20 Checking the cylinder head base
plane
Fig. 4-1-21 Measuring the warps of the air
exhaust manifold pipe and the fitting surface
threads of the cylinder head bolts (see Fig. 4-1-19), and
any damage caused by incorrect tool usage.
Attention:
Any suspicious bolt should be replaced.
(3) Check whether there is any crack in the cylinder head,
especially in the area between valve seats and at the
exhaust port.
(4) Check whether there is any corrosion on the base
plane of the cylinder head, or any sand inclusion or
spongy pore in the cylinder head.
Attention:
Do not try to weld up the cylinder head.
The damaged cylinder head should be replaced
immediately.
(5) Check the flatness of cylinder head plane and the
flatness of fitting surface between air intake and exhaust
manifold pipes.
These surfaces can be grinded. If the ―irregularities‖ of
these surfaces excesses the specified limits, these
surfaces should be grinded to make them meet the
technical requirements, and if they excess too much, they
should be replaced.
Standard
Limitation
Warp of the base plane
of cylinder head
≤0.05 mm
0.10 mm
(6) Measure the warp of the fitting surface between air
exhaust manifold pipe and cylinder head with straight
scale and feeling gauge.
If the measured value is between the specified limitation
and the standard value, then the fitting surface between
the air exhaust pipe and the cylinder head should be
reground.
Replace the air exhaust manifold pipe if the measured
value excesses the specified limitation.
Wrap of exhaust pipe
Standard
Limitation
≤0.05 mm
0.10 mm
Reassembly
Reinstalling the cylinder head
○
17
(1) Installing the valve
——Before installing the valve, the engine oil should be
applied onto the external surface of the valve stem and
the internal surface of the valve guide.
Mobil APICI-4 lubricating oil
