Valve Lapping; Free Length And Tilt Of Valve Spring; Valve Spring Setting Load - Kubota D1503-M Workshop Manual

03-M-E3B, 03-M-DI-E3B, 03-M-E3BG WSM

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.

Free Length and Tilt of Valve Spring

1. Measure the free length (B) of valve spring with vernier calipers.
If the measurement is less than the allowable limit, replace it.
2. Put the valve spring on a surface plate, place a square on the
side of the valve spring.
3. Check to see if the entire side is in contact with the square.
Rotate the valve spring and measure the maximum tilt (A).
If the measurement exceeds the allowable limit, replace it.
4. Check the entire surface of the valve spring for scratches.
If there is any defect, replace it.
Tilt (A) Allowable limit
Factory spec.
Free length (B)
Allowable limit
(A) Tilt

Valve Spring Setting Load

1. Place the valve spring on a tester and compress it to the same
length it is actually compressed in the engine.
2. Read the compression load on the gauge.
3. If the measurement is less than the allowable limit, replace it.
Factory spec.
Setting load /
Setting length
Allowable limit
S-79
DIESEL ENGINE
W10288140
1.0 mm
0.039 in.
41.7 to 42.2 mm
1.65 to 1.66 in.
41.2 mm
1.62 in.
(B) Free Length
W10289350
118 N / 35.0 mm
12.0 kgf / 35.0 mm
26.5 lbf / 1.38 in.
100 N / 35.0 mm
10.2 kgf / 35.0 mm
22.5 lbf / 1.38 in.
W10784360
KiSC issued 07, 2008 A