Toro Workman 3000 Series Service Manual page 135

2. Disassemble piston pin, piston and connecting rod:
A. Insert special tool. Push rod and Guide B, into
piston pin. Set piston and connecting rod assembly
on base. Make sure front mark (arrow) stamped on
piston top surface faces up.
B. Use a press to drive out piston pin. Keep disas­
sembled piston, pin and connecting rod together ac­
cording to cylinder number.
Piston and Connecting Rod Inspection
NOTE: Piston and piston pin must be replaced as an as­
sembly.
1. Check piston for scuffing, seizure, cracks or other
damage and replace if necessary.
2. Check oil return hole in oil ring groove and oil hole in
piston boss.
3. Check piston pin hole and replace piston if signs of
seizure or damage are evident.
4. Insert piston pin into piston pin hole with your thumb.
You should feel a slight resistance. Replace piston and
pin if pin can be easily inserted or there is free play.
5. Check piston ring for damage, wear or bending and
replace if necessary. Also make sure you install new
rings if a new piston is installed.
6. Check clearance between piston ring and groove.
When clearance exceeds the limit, replace the rings
and/or piston.
7. Insert piston ring into cylinder bore, putting it against
top of piston head then pushing it in. With piston ring at
a right angle to cylinder, measure ring gap with a feeler
gauge. Replace piston ring if gap exceeds the limit.
Standard value
No. 1 ring 0.15 – 0.30 mm (.0059 – .0118 in.)
No. 2 ring 0.35 – 0.50 mm (.0138 – .0197 in.)
Oil ring 0.2 – 0.7 mm (.008 – .028 in.)
Limit
No. 1 ring .08 mm (.031 in.)
No. 2 ring .08 mm (.031 in.)
Oil ring 1.0 mm (.039 in.)
Workman 3000/4000 Series
Push rod
Front mark
Guide B
Piston ring
Page 3 – 97
Base
Figure 201
Figure 202
Figure 203
Push with piston
Piston ring gap
Figure 204
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