3.3.12. Pistons and rods

Elements of piston group

The correct arrangement of the piston concerning a rod on diesel engines


1. Before check of pistons with rods remove piston rings from pistons and carefully clear pistons.
2. For removal of piston rings from pistons unclench a ring and insert under a ring, evenly on circles, two or three old edges of the probe and on them shift a ring from the piston. Be careful, do not scratch the piston the ends of a ring. Rings very fragile can also burst if to unclench them very strongly. Working edges of rings are very sharp therefore handle with them with care not to be cut.
3. You hold each set of rings together with the piston for repeated installation them on the places.
4. Clear all traces of a deposit from the top part of the piston.
5. Remove a deposit from flutes under piston rings in the piston, using an old ring.
6. After removal of a raid clear the piston with a rod the corresponding solvent and wipe them dry.
7. At assembly of the engine it is desirable to use new piston rings.
8. Carefully examine each piston on existence of cracks around a skirt and openings under a piston finger.
9. Check wear on a piston skirt, an opening in a piston head, and also burned in the top part of the piston.
10. Traces of pointed corrosion on the piston specify that cooling liquid got to the combustion chamber. It is necessary to find the reason of hit of liquid in the combustion chamber and to eliminate it.
11. On engines with the aluminum block of cylinders with damp sleeves it is impossible to replace pistons separately; pistons are delivered complete with rings and sleeves.
12. Check each rod for wear and existence of cracks, and also distortion of a form.
13. It is recommended to make replacement of hairpins and nuts of fastening of the lower head of a rod at each dismantling.
14. On all petrol engines piston fingers are pressed in the top head of a rod therefore replacement of rods needs to be made in a specialized workshop.
15. On diesel engines piston fingers are established on the sliding landing and recorded in the piston by two lock rings. On these engines pistons and rods can be divided as follows.
16. Using an edge of the thin screw-driver remove a lock ring from the piston and a hand squeeze out a piston finger. At repeated installation of a piston finger use only new lock rings.
17. Check a piston finger and the bearing of the top head of a rod for wear.
18. Rods usually do not demand replacement if before it there was no jamming of the engine.
19. Install the piston on the top head of a rod so that the arrow on the bottom of the piston settled down from marking of the lower head of a rod. Grease a piston finger and implant it into the piston and the top head of a rod. Check that the piston easily and freely turned on a piston finger then record a piston finger new lock rings. Check that each lock ring was correctly located in a piston flute (see rice. The correct arrangement of the piston concerning a rod on diesel engines).