Checking the thermal clearance of the piston rings
Install the ring from the top into the cylinder and then slide it into the bottom of the cylinder so that it is positioned at a distance of about 15 mm from the bottom edge of the cylinder (with an old piston).
| Piston ring | Thermal gap | |
| New | Maximum allowable value | |
| Compression rings | 0,20-0,40 | 0,8 |
| Oil scraper ring | 0,25-0,50 | 0,8 |
Checking the height clearance between the groove and the ring
Before checking, clean the groove in the piston.
| Piston ring | Height clearance between groove and ring | |
| New | Maximum allowable value | |
| Compression rings | 0.06-0.09 mm | 0.20 mm |
| Oil scraper ring | 0.03-0.06 mm | 0.15 mm |
Measure at right angles to the longitudinal axis of the cylinder, approximately 10 mm above the bottom edge of the piston skirt.
Deviations from the nominal dimensions are not more than 0.04 mm.
Checking the cylinder diameter
Take measurements crosswise in three places in the transverse (A) and longitudinal (IN) directions.
Deviations from the nominal dimensions are not more than 0.08 mm.
Attention! It is forbidden to measure the diameters of the cylinders on the engine installed on the assembly stand, since in this case the measurement results may be distorted due to the deformation of the cylinder block under its own weight.
Piston and cylinder dimensions:
- Nominal piston size: 80.965 mm*.
- Nominal cylinder size: 81.01 mm*.
* Dimensions without graphite coating (thickness 0.02 mm). Graphite coating is erased at the beginning of operation.
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