BMW 3 series E30

Since 1983-1994 of release

Repair and car operation

3.2.21. Check of a condition of pistons and rods

THE GENERAL DATA

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The prevention

Rings are subject to obligatory replacement irrespective of their condition.

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PERFORMANCE ORDER

1. Accurately clear pistons of a deposit and cautiously remove rings. 2. Cautiously remove rings by means of the adaptation. 3. Clear of a deposit of the bottom of pistons, wash out pistons and rods solvent, carefully clean drainage oil apertures in piston flutes. 4. Remove a deposit from flutes of piston rings. 5. If traces of considerable deterioration on the piston are absent and if расточка cylinders it is not required, pistons should not be changed. Normal deterioration is shown in the form of traces of uniform vertical development on a rubbing surface of the piston and in the form of small easing of landing top компрессионного rings. Nevertheless, replacement of piston rings is obligatory. 6. Carefully check up presence of cracks on the bottom and a piston skirt, on lugs of a piston finger and on airfields of piston rings. If on a piston skirt are observed сколы and teases it specifies in a frequent overheat of the engine. Careful check of systems of greasing and cooling in this case is required. The burn-out of the bottom of the piston testifies to work of the engine with wrong installation of the moment of ignition. The reason обгорания the piston bottoms along the edges as a rule is abnormal combustion (detonation). If the specified defects it is necessary to find their reason are found out and to eliminate. On late models system refusal recycling can be the reason of such defects. 7. Corrosion of the piston in the form of small poles (питтинга) testifies to penetration into the combustion chamber (and also in картер коленвала) a cooling liquid. 8. Measure a backlash between a flute and a new ring in 3–4 places on length of a ring. It is necessary to consider that at different rings standard backlashes differ. If the backlash exceeds the established limit it is necessary to replace the piston. 9. Check up a backlash between the piston and the cylinder, having measured internal diameter of the cylinder and diameter of the piston from the given cylinder in corresponding directions. If the backlash exceeds the established limit the block of cylinders is subject расточке, and and rings it is necessary to replace pistons repair. 10. Check up a backlash between a piston finger and a rod head for what shake the piston and a rod in opposite directions. If люфт notable repair of this connection in car-care centre is necessary. 11. Removal of pistons from rods, and also check of rods and their editing are carried out in car-care centre. If knot the piston-rod in a normal state (люфты are absent also all backlashes in norm) it is not necessary to assort it. 12. Check up presence on rods of cracks and other damages. Remove covers шатунных bearings, get bearings, wipe landing surfaces on a cover and on a rod, check up presence of cracks, scratches and задиров. After check collect a rod, having established into place bearings, tighten nuts by hand.