Normal value: upper compression ring is 0.03-0.07mm, lower compression ring is 0.02-0.06mm. Limit value: upper compression ring - 0.1 mm, lower compression ring - 0.1 mm.
Pic. 4.31. Checking clearance between piston ring and groove
2. Install the piston ring in the cylinder bore and press it with the piston so that it is at right angles to the bore of the cylinder (pic. 4.32). After that, the clearance in the piston ring lock is measured using a gauge. If the clearance in the piston ring lock is greater than the allowable value, the piston ring must be replaced with a new one.
Pic. 4.32. Checking the gap between the ends of the piston rings
Normal value: upper compression ring - 0.025-0.40mm, lower compression ring - 0.40-0.55mm, oil scraper ring: SOHC - 0.20-0.60mm, DOHC -0.10-0.35mm.
Permissible value: compression rings - 0.8 mm, oil scraper ring - 1.0 mm.