Relative position of piston ring locks
The engine's service life without cylinder boring can be significantly increased by installing a special oil scraper piston ring.
1. Remove the upper sealing ring, the middle sealing ring and the oil scraper ring one by one. To remove the rings, insert thin steel plates (feelers are also possible) under the ring in several places evenly around the piston perimeter and slide the piston ring off the piston using the plates.
2. Check the size of the gap in the ring lock. To do this, sequentially insert all the rings from the top side into the working cylinder liner.
3. Using the inverted piston, push the ring down into the cylinder to a depth of 15 mm and measure the gap in the ring lock with a feeler gauge. The gaps in the ring lock are not adjustable, so if the gap increases beyond the permissible limit, the ring must be replaced.
4. To determine the piston clearance in the cylinders, measure the cylinder diameter. The cylinders are measured in the longitudinal and transverse directions at three levels along the cylinder height. Then subtract the piston diameters from the cylinder diameters, which will give the piston clearance in the cylinder. If the clearance is outside the permissible limits, new sets of pistons and cylinder liners should be installed.
5. Install the piston rings onto the piston.
6. Check the clearance in the groove between the piston and the piston ring, lubricate the rings with oil and turn them on the piston to obtain the correct mutual arrangement of the locks.