Piston Inspection - MTD P90 series Shop Manual

Piston Inspection

Feeler gauge
Figure 10.9
Top piston ring
Middle piston
ring
3-piece oil ring
Figure 10.10
Top ring
Middle ring
Figure 10.11
Piston ring
Crankshaft, piston and connecting rod
1. Clean the piston and remove all carbon from the rings
and ring groves.
2. Clean the cylinder bore and remove all carbon.
3. Insert one ring into the cylinder. Push it down about
one inch from the top. See Figure 10.9.
4. Measure the end gap with a feeler gauge and com-
pare to the chart at the end of this chapter.
See Figure 10.9.
5. Repeat steps 3 and 4 on the other rings.
NOTE: Piston rings are not available as service parts. If
any of the end gaps are out of spec, the engine
must be short blocked.
6. Install rings back onto the piston.
NOTE: The compression rings on the MTD engine have
different profiles. It is important that the proper pro-
filed ring is on the right groove. See Figure 10.10.
NOTE: To help identify the top surface of the piston rings,
They have letter(s) etched on them.
See Figure 10.11.
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