Weichai America Corp.
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Fig. 2-18 A Depth Micrometer
Reference Table 2-3 for valve recession requirements. If valve recession exceeds the allowed
range, the cylinder cover must be replaced to ensure engine reliability. If valve recession doesn’t
exceed allowed range, disassemble the valve and check the sealing surface between the valve and
valve seat for wear and abnormal damage.
Table 2-3 Valve Recession Specifications
Required value of valve recession (mm)
Intake valve
1.00~1.45
Exhaust valve
1.00~1.45
3. Clearance between valve rod and valve guide pipe:
Internal surface of valve guide pipe is the contacting surface between valve rod and valve guide
pipe, if clearance between valve rod and valve guide pipe exceeds allowed value due to abrasion,
then the guide effect will at state, which may affect reliability of the engine. The inner diameter
of guide pipe can be measured with an inside micrometer, as shown in Fig. 2-19. Outer diameter
of valve rod can be measured with an outside micrometer. Both allowed ranges for clearance
between intake valve rod and its guide pipe, exhaust valve rod and its guide pipe are
0.03~0.06mm. If clearance exceeds allowed range, the cylinder cover must be replaced to ensure
reliability of diesel engine
Fig. 2-19 A inner Micrometer