Kubota MX5100, Workshop Manual

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1-S56
MX5100, WSM ENGINE
Cylinder Head Flaw
1. Prepare an air spray red check.
2. Clean the surface of the cylinder head with the detergent (2).
3. Spray the cylinder head surface with the red permeative liquid
(1). Leave it five to ten minutes after spraying.
4. Wash away the red permeative liquid on the cylinder head
surface with the detergent (2).
5. Spray the cylinder head surface with the white developer (3).
6. If flawed, it can be identified as red marks.
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Valve Recessing
1. Clean the cylinder head surface, valve face and valve seat.
2. Insert the valve into the valve guide.
3. Measure the valve recessing with a depth gauge.
4. If the measurement exceeds the allowable limit, replace the
valve.
5. If it still exceeds the allowable limit after replacing the valve,
replace the cylinder head.
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Clearance between Valve Stem and Valve Guide
1. Remove carbon from the valve guide section.
2. Measure the valve stem O.D. with an outside micrometer.
3. Measure the valve guide I.D. with a small hole gauge, and
calculate the clearance.
4. If the clearance exceeds the allowable limit, replace the valves.
If it still exceeds the allowable limit, replace the valve guide.
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(1) Red Permeative Liquid
(2) Detergent (3) White Developer
Valve recessing
Factory spec.
0.05 (protrusion) to
0.15 (recessing) mm
0.002 (protrusion) to
0.0059 (recessing) in.
Allowable limit
0.40 (recessing) mm
0.016 (recessing) in.
(1) Cylinder Head Surface (A) Recessing
(B) Protrusion
Clearance between
valve stem and valve
guide
Factory spec.
0.040 to 0.070 mm
0.0016 to 0.0027 in.
Allowable limit
0.10 mm
0.0039 in.
Valve stem O.D. Factory spec.
7.960 to 7.975 mm
0.3134 to 0.3139 in.
Valve guide I.D. Factory spec.
8.015 to 8.030 mm
0.3156 to 0.3161 in.