Yanmar 3TNV Series Service Manual page 117

4. Disassembly, Inspection and Reassembly of Engines
(c) Piston ring, ring groove and end clearance
measurement
Except for the top ring, to measure the piston ring
groove width, first measure the width of the piston
ring. Then insert the piston ring into the ring.
Then insert the piston ring into the ring groove.
Insert a thickness gage in between the piston ring
and groove to measure the gap between them.
Obtain the ring groove width by adding ring width
to the measured side clearance.
To measure the end clearance, push the piston
ring into the sleeve using the piston head, insert a
thickness gage in end clearance to measure.
The ring shall be pushed in to approx. 30 mm
above the bottom end of the cylinder. For the top
ring, measure only the piston ring joint end
clearance in normal state.
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