Nanni 5.280HE Workshop Manual page 89

03-M Series, WSM
Correcting Valve and Valve Seat
NOTE
• Before correcting the valve and seat, check the valve stem
and the I.D. of valve guide section, and repair them if
necessary.
• After correcting the valve seat, be sure to check the valve
recessing.
1) Correcting Valve
1. Correct the valve with a valve refacer.
Factory
Valve face angle
spec.
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 1.047 rad (60 °) (intake
valve) or 0.785 rad (45 °) (exhaust valve) valve seat cutter.
2. Resurface the seat surface with a 0.523 rad (30 °) valve seat
cutter to intake valve seat and with a 0.262 rad (15 °) valve seat
cutter to exhaust valve seat so that the width is close to specified
valve seat width (2.12 mm, 0.0835 in.).
3. After resurfacing the seat, inspect for even valve seating, apply a
thin film of compound between the valve face and valve seat, and
fit them with valve lapping tool.
4. Check the valve seating with prussian blue. The valve seating
surface should show good contact all the way around.
Factory
Valve seat angle
spec.
(A) Check Contact
(B) Correct Seat Width
(C) Check Contact
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.
S-72
DIESEL ENGINE
1.047 rad
IN.
60 °
0.785 rad
EX.
45 °
1.047 rad
IN.
60 °
0.785 rad
EX.
45 °
(a) Identical Dimensions
(b) Valve Seat Width
(c) 0.523 rad (30 °) or 0.262 rad (15 °)
(d) 0.262 rad (15 °) or 0.523 rad (30 °)
(e) 0.785 rad (45 °) or 1.047 rad (60 °)
W10283500
W10288140
KiSC issued 08, 2012 A