Toro Groundsmaster 328-D, Service Manual

Page: 88 / 402

Oversized Pistons, Cylinder Bore and Rings (Fig. 73, 74, 75)
1. Check the piston for wear, signs of seizure or nicks.
Replace it if it is defective.
2. Measure the piston outside diameter. If the clearance
between the piston and the cylinder exceeds 0.01 18 in.
(.3 mm), replace the piston.
NOTE: The piston O.D. should be measured at the
lower end of the skirt across the thrust faces, or on
access points perpendicular to the piston pin direction.
3. Thoroughly clean the carbon deposits from the piston
and ring grooves. A ring groove cleaner, or piece of a
discarded ring may be used to clean the ring grooves.
4. Measure the piston ring side clearances using a
thickness gauge.
If the piston ring side clearance exceeds the service limit
in the chart below, the ring must be replaced.
NOTE: In the case of a tapered ring (No. 1), measure
the clearance on the bottom, or widest area of the ring.
Figure 73
Measuring piston outside diameter
Figure 74
Measuring piston ring side clearance
5. Measure the piston ring gap clearance. Insert the ring
into the least worn area of the cylinder by pushing it into
place with the piston. The standard gap is 0.0059 -
0.0157 inch (0.15 - 0.4 mm). If the gap exceeds 0.0590
inch (1.5 mm) the ring must be replaced.
Figure 75
Measuring piston ring gap clearance
Cylinder Block Overhaul Page 4 - 58 Groundsmaster
®
300 Series