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