Doosan DX22 - General Information; Inspecting the Valve Guide; Inspecting Valves; Valves

10. Cylinder Block/Head
141
Valves
General Information
The overhead valve is operated by the tappets, pushrods
and rocker arms on the camshaft.
Inspecting Valves
Wash the valve with clean engine oil and inspect it as follows.
1. Valve stem outside diameter
EDX22190170
1) Measure the valve stem outside diameter in three places
(top, middle, bottom).
2) If the amount of wear exceeds the allowable limit, replace
the valve.
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2. Valve seat mating surface
1) Check the valve seat mating surface for scratches or
damage.
2) If necessary, grind the surface with sandpaper. However,
if the damage is severe, replace the part.
3. Valve head thickness
EE1OM066
1) Measure the thickness of the valve head.
2) If the measurement is below the allowable limit, replace
the valve.
Inspecting the Valve Guide
1. Install the valve on the cylinder head.
2. Measure the clearance between the valve guide and
valve arising from the movement of the valve.
EA0M4052
3. If the clearance is excessively large, measure the valve
and replace either the valve or valve guide, whichever
part is more worn.
Reference value Allowable limit
Intake valve
stem
Ø7.963 ~ Ø7.977 mm
(Ø0.3135 ~ Ø0.3141 in.)
Ø7.943 mm
(Ø0.3127 in.)
Exhaust
valve stem
Ø7.950 ~ Ø7.964 mm
(Ø0.3129 ~ Ø0.3135 in.)
Ø7.920 mm
(Ø0.3118 in.)
106.5
+5
0
121.5 ± 1(Straight Grinding)
Valve stem
Reference value Allowable limit
Intake valve (A)
3.2 ~ 3.6 mm
(0.1260 ~ 0.1417 in.)
2.7 mm
(0.1063 in.) or
less
Exhaust valve
(A)
3.9 ~ 4.3 mm
(0.1535 ~ 0.1693 in.)
3.4 mm
(0.1339 in.) or
less
A
Measuring
location