Kubota M108S, Workshop Manual

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1-S51
M108S, 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.
W1076542
Valve Recessing
1. Clean the cylinder head, the valve face and 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.
If it still exceeds the allowable limit after replacing the valve,
replace the cylinder head.
W1061543
Valve Lapping
1. Apply compound evenly to the valve lapping surface.
2. Insert the valve into the valve guide. Lap the valve onto its seat
with a valve flapper or screwdriver.
3. After lapping the valve, wash the compound away and apply oil,
then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate. If it is less than 70 %, repeat valve lapping again.
IMPORTANT
■
• When valve lapping is performed, be sure to check the valve
recessing and adjust the valve clearance after assembling
the valve.
W1061709
(1) Red Permeative Liquid
(2) Detergent (3) White Developer
Valve recessing
Factory
spec.
Intake
valve
(recessing)
0.60 to 0.80 mm
0.024 to 0.031 in.
Exhaust
valve
(recessing)
0.850 to 1.05 mm
0.0335 to 0.0413 in.
Allowable
limit
(recessing)
1.2 mm
0.047 in.
(1) Cylinder Head Surface (A) Recessing
(B) Protrusion
(1) Correct
(2) Incorrect (3) Incorrect
KiSC issued 06, 2007 A