Install a piston ring in the cylinder.

Advance a piston ring to the middle of the cylinder by means of the piston.

Fig. 2.155. Check of gaps in the lock of piston rings: 1 – piston ring; 2 – piston; 3 – probe

Measure a ring gap in the lock by a set of probes (fig. 2.155).

Gaps in locks of rings:

– for the top compression ring the gap has to be within 0,15–0,30 mm for K4M 760 and 761 engines, for other engines – within 0,15–0,35 mm;

– the gap for the lower compression ring has to be within 0,4–0,6 mm;

– the gap for an oil scraper ring has to be within 0,2–0,9 mm.

Replace piston rings if gaps go beyond the admission, and if gaps remain outside the admission and with new rings, replace the block of cylinders.