Valves; Valve Seats - Toro Workman 3000 Series Service Manual

Valves

1. Carefully clean each valve with a wire wheel to
remove all carbon deposits.
2. Check the valve face and valve stem for excessive
wear, damage, cracks or deformation. If any of these
conditions exist, the valve must be replaced. It is possi­
ble to reface the valve if the valve head thickness
(margin width) is not less than the service limit (Fig.65).
If the margin of the resurfaced valve is less than the
service limit, replace the valve.
Minimum valve head thickness (margin width):
0.5 mm (0.020 in.)
3. Check the tip of the valve stem for wear or pitting.
Replace the valve if the tip is worn.

Valve Seats

1. Check the valve seats for damage and indications of
incorrect contact (Fig. 66).
Maximum valve sinkage: 1.5 mm (0.06 in.)
2. The valve seat can be resurfaced (Fig. 67). Resurface
the valve seat so it contacts the mid-portion of the valve
face.
3. After cutting new valve seats, use lapping compound
to lap the valve to the seat. After lapping, thoroughly
clean the valve seat and valve areas to remove any
traces of lapping compound.
4. Put a light coat of Prussion blue dye on the valve seat
area. Install the valve. Hold the valve down and rotate
it 1/4 turn, then turn the valve back to the original
position. Remove the valve and examine the valve
seat. The valve seat should show an even wear pattern
from contact with the valve. Examine the valve. The dye
should be evenly distributed around the valve and in the
center of the valve face.
Liquid Cooled Diesel Engine Page 4 - 62
Figure 65
Figure 66
Figure 67
Workman 3300-D/4300-D