Height clearance
1. Check the height gap between the grooves and the rings by inserting the ring into the corresponding groove (1 - piston ring, 2 - piston, 3 - set of probes).
2. 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.
Gap in the castle
3. 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. For rings of normal size, caliber A.96137 can be used.
4. The gap should be between 0.25-0.45 mm for all new rings. The maximum allowable wear gap is 1 mm. If the gap is insufficient, file the butt surfaces, and if it is increased, replace the rings.