Check of pistons and rods

After removing the pistons and connecting rods necessary to Troubleshooting. If there is evidence of the details of scoring, cracks or excessive wear should be replaced. The pistons and connecting rods must be checked as follows:

- Measure the clearance height of the piston rings in the grooves of the piston, piston rings alternately setting a corresponding groove (Fig. 68). Determined by the gap between the probe end ring and its groove. If the gap is over 0.15 mm, the piston ring or worn. The nominal size of 0.02-0.05 mm. Scraper ring may consist of three parts. In this embodiment, measured ring gap adjustment impossible. In other engines use a single ring. It is subject to the same rules as for the compression piston rings;

- Alternately set in all the cylinders, piston rings with the bottom side of the crankcase. Piston rings to press down about 15 mm. This ensures their installation in the cylinder without distortions;

- Introduce the probe into the gap between the ends of the ring, as shown in Fig. 69, for measuring the gap in the piston ring seals. The values refer to the gap. "Technical Data". The gaps are different for different engines;

- If the gap is too small (for example, new rings, which also need to be measured), the ends of the rings can be treated with a file. When the gap is too large ring to be replaced;

- Check piston pins and rods sleeve for scoring. If you find that damaged at least one connecting rod, it is necessary to replace the entire set;

- Check the connecting rods to the correct machine on the twisting and bending deformation;

- Bolts connecting rod bearings and connecting rods nuts must always be replaced - for re-use are not suitable;

- A new requirement for the set of engines is the measurement values for the preliminary tightening of bearings of rods. This requires the caliper. For this purpose, connecting rods and bearing caps without liners connecting bolts and tighten nuts to 30 Nm (dovorachivat the desired angle is not required). Measure the width of the well (Fig. 70) of the insert rod bearing and write it. Then, measure the inner diameter of the connecting rod bearing b. Subtract the diameter of the bearing and the inner diameter b. The engine capacity of 1.0 liter difference should be 0.5 mm. In other engines, it may be up to 1.5 mm. Otherwise, the bearing shells must be replaced.