5.15. Rods and pistons - check of a state
1. Accurately clear pistons of a deposit and carefully remove rings.
2. Remove a deposit from flutes of piston rings (photo).
3. Wash out pistons and rods solvent, carefully clean drainage openings in flutes of the piston and an opening in a rod (photo).
4. If traces of considerable wear are absent and if boring of cylinders is not required, then pistons should not be changed. Normal wear is shown in the form of traces of uniform vertical development on the rubbing surface of the piston and in the form of small weakening of landing of the top compression ring. Nevertheless, replacement of piston rings at capital repairs of the engine is obligatory.
5. Carefully check existence of cracks on a piston skirt, on lugs of a piston finger and on airfields of piston rings.
6. If on the piston chips and teases are observed, then it indicates a frequent overheat of the engine. In this case careful check of lubrication systems and cooling is required. The burn-out in the bottom of the piston demonstrates operation of the engine with the wrong installation of the moment of ignition. At the edges as a rule abnormal combustion (detonation) is the reason of an obgoraniye of the bottom of the piston. If the specified defects are found, then it is necessary to find their reason and to eliminate.
7. Corrosion of the piston in the form of small poles (pitting) demonstrates penetration into the combustion chamber (and also in a crankshaft case) cooling liquid.
8. Measure a gap between a flute and a new ring (photo). If the gap exceeds the set limit, then the piston should be replaced.
9. Check a gap between the piston and the cylinder, having measured diameter of the cylinder (see above) and diameter of the piston from this cylinder (photo). If the gap exceeds the set limit, then the block of cylinders is subject to boring, and pistons and rings should be replaced repair.
10. Check a gap between a piston finger and a head of a rod for what shake the piston and a rod in opposite directions. If a side play notable, then an opening under a finger it is necessary to develop and establish a new finger.
11. Repair of pistons and rods is carried out in car service.
12. Check existence on rods of cracks and other damages. Uncover conrod bearings, get bearings, wipe landing surfaces on a cover and on a rod, check existence of cracks, scratches and zadir. After check collect a rod, having installed into place bearings, tighten nuts by hand.