Using a new ring, place the outer edge of the ring in the oil control ring groove.
Roll the ring, in its respective groove, entirely around the piston. Make sure the ring is "free" in the groove.
With a feeler gage check the side clearance of each oil control ring in its respective groove. See Figure
1. Feeler Gage
2. Oil Control Ring
Measuring Piston Diameter
Excessive side clearance indicates ring groove wear and requires piston replacement.
Check piston to cylinder liner running clearance, as follows:
Measure and record the piston skirt diameter. With the piston at room temperature, place an outside micrometer 27.43 mm (1.080 in.) below the bottom land of the oil control ring 90 degrees from the pin bore. See Figure
Piston Skirt Diameter Measurement
Measure cylinder liner inside diameter. Record the reading.
Subtract the piston skirt diameter from the cylinder liner I.D. The resulting dimension is the piston to cylinder liner running clearance.
If running clearance is not within specifications, replace the piston.
Inspection of Piston Ring
Follow these steps to inspect the piston rings.
Visually inspect new rings for cleanliness.
Faulty rings cannot always be detected by visual inspection. Whenever a piston is removed from a cylinder, it is recommended that piston rings be replaced.
Prior to installing the rings on the piston, check each ring for proper gap as follows:
Push the ring down into the cylinder bore making sure the ring is square with the cylinder wall.
Measure the gap between the ends of each ring with a feeler gage. See Figure
. Discard any new ring which does not meet the specifications.