Check the height clearance between grooves and rings as shown in fig. 2-28 by inserting the ring into the corresponding groove.
Nominal (estimated) the gap for the upper compression ring is 0.045-0.08 mm, for the second - 0.025-0.06 mm and for the oil scraper - 0.02-0.055 mm. The maximum allowable wear gaps are 0.15 mm.
Check the gap in the lock of the piston rings with a set of feelers, inserting the rings into a gauge having a hole diameter equal to the nominal diameter of the ring with a tolerance of±0.003 mm.
The gap should be within 0.25-0.45 mm for new rings. If the gap is insufficient, file the butt surfaces, and if it is increased, replace the rings. The maximum allowable clearance for wear is 1 mm.