Lay out the piston assemblies with connecting rods and new piston rings in such a way that the set of rings corresponds to the given cylinder on which the gap in the lock will be measured.
Figure 3.46. Measuring the gap in the piston ring joint
Insert the top ring into the first cylinder and push it in with the piston crown so that the ring inside the cylinder becomes perpendicular to its axis. The ring must be located at the bottom of the cylinder in a position corresponding to the bottom dead center. The gap in the piston ring lock is measured with a feeler gauge (figure 3.46). Compare the result with the required value.
If the gap is greater or less than specified, repeat the measurement to ensure the ring can be installed.
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If the gap is too small, it must be increased, otherwise, during engine operation, the ends of the ring will connect, which can cause serious damage. The gap in the piston ring lock can be increased by carefully filing the ends with a thin file. Place the file in a vice with soft jaws and carefully move the ring over it, removing excess material.
The gap may exceed the established one, but should not be more than 1 mm.
The measurement should be repeated to ensure the ring fits properly.
Repeat the measurements for each ring installed in the first cylinder, as well as for the remaining rings installed in the other cylinders.
After measuring the ring gaps and adjusting them, the rings can be installed on the pistons.
The oil scraper ring is installed first (the lowest on the piston).
Figure 3.47. Location of oil scraper ring elements and locks: 1 – oil scraper ring; 2 – oil scraper ring (expander); 3 – lower guide; 4 – expander; 5 – upper guide; 6 – piston pin
Figure 3.48. Installing oil scraper ring components
This ring consists of three elements. Install the spacer/expander into the groove (figure 3.47), then install the lower oil scraper ring guide. When installing the guides, do not use a ring installation tool, as this may cause them to break. Insert one end of the guide into the piston groove between the separator and the horizontal surface of the groove and, holding it firmly, insert the other end of the ring into the groove with your finger (figure 3.48). Install the second guide in the same way.
After installing all the oil scraper ring components, make sure that the upper and lower guides rotate freely in the groove. Arrange the oil scraper ring locks in accordance with the drawing 3.47.
The middle ring is installed next. It has an "R" mark stamped on it, which should be directed towards the bottom of the piston.
Caution! Always follow the instructions on the piston ring packaging; different manufacturers may have different markings.
Caution! Do not confuse the upper and lower compression rings, as they have different cross-sectional profiles.
Figure 3.49. Location of marks on compression piston rings
Install the piston ring installer, ensure the marks are facing the piston bottom, and move the corresponding ring into the piston center groove (figure 3.49). Do not spread the ends of the ring more than is required for it to pass over the piston. Instead of the device, you can use metal strips.
Figure 3.50. Installation position of compression rings and location of their locks: 1 – upper compression ring lock; 2 – lower compression ring lock; 3 – upper compression ring; 4 – lower compression ring; 5 – piston pin
Install the upper compression ring in the same way. Make sure the marks are facing up. Do not confuse the upper and lower compression rings. Arrange the ring locks according to the drawing 3.50.