3.5.12. Pistons and rods

Piston and rod

1. Lock ring

2. Piston finger

3. An arrow on a piston head

4. Piston

5. Rod

6. Rod tag


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 a circle 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 piston rings very sharp therefore handle with them very with care not to be cut. You hold each set of rings together with pistons for repeated installation them on the places.

3. Clear all traces of a deposit from the top part of the piston.
4. Remove a deposit from flutes under piston rings in the piston, using an old piston ring.
5. After removal of a raid clear the piston with a rod the corresponding solvent and wipe dry.
6. Carefully examine each piston on existence of cracks around a skirt and openings under a piston finger.
7. Check wear on a piston skirt, an opening in a piston head, and also burned in the top part of the piston.
8. 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.
9. Measure diameter of the piston.
10. Define a piston gap in the cylinder for what from diameter of the cylinder take away diameter of the piston and divide into two.
11. Check each rod for wear and existence of cracks, and also distortion of a form.
12. 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.
13. 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.
14. 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.
15. Check a piston finger and the bearing of the top head of a rod for wear.
16. Rods usually do not demand replacement if before it there was no jamming of the engine.
17. On the engine of 1,7 l collect the piston and a rod so that the adjusting tag on a piston head (it is specified by an arrow) was from the same party, as a tag on a rod (it is specified by an arrow).
18. On engines of 2,0 l collect the piston and a rod so that the arrow on a head of the piston showed aside, opposite to a tag on a rod.
19. 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. On engines of 2,0 l establish lock rings so that their locks were directed up.
20. On engines of 2,0 l the section of a lock ring has to be directed the piston up.