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4.3.12. Check of a condition of conrod and piston assemblies

 PERFORMANCE ORDER

1. Before starting check of a condition of their conrod and piston assemblies it is necessary to clear carefully. Do not forget to remove from pistons old piston rings also.

2. Carefully move apart the lock of the top compression ring and remove it from the piston at the top. Working in a similar manner, remove the remained second compression ring, then oil scraper. In order that in the course of removal of a ring did not fail in the flutes located above, use pair of old lezviyny probes. Try not to scratch rings the surface of the piston. Remember that rings are made of rather fragile material and at excessive expansion can break. Do not forget that about keen edges of piston rings it is easy to cut fingers. Pay attention to that fact that the oil scraper ring consists of three separate parts - a dilator and two side sections. All rings have to be removed at the top the piston. If old rings are in good repair and are subject to further use, at assembly they have to be established strictly on the former places. Exempt pistons of all assemblies from rings.

3. Carefully scratch out coal deposits from the top part of pistons. After the main layer of deposits is removed, it is possible to use a manual wire brush, or an emery paper. Try not to mention piston metal as it can be easily damaged in view of the softness during cleaning.
4. A fragment of an old ring clean piston flutes, having removed from them the accumulated coal deposits. Be careful, try not to damage walls and a bottom of flutes. Do not cut fingers.
5. Having finished the procedure of cleaning, wash out pistons and rods in kerosene or other suitable solvent, then carefully dry. Make sure of passability of maslovozvratny openings in flutes under installation of piston rings.
6. If walls of pistons and a mirror of cylinders are in satisfactory condition (are not damaged and moderately worn-out), and the block of cylinders does not need a pro-point (see Cleaning and check of a condition of the block of cylinders/case of the engine), at assembly can be used old piston rings. Normal wear of pistons is shown in the form of a uniform wipe of persistent surfaces in the vertical direction and is followed by an easy weak point of landing of piston rings in the flutes.
7. Attentively examine pistons on existence of cracks in regions of skirts, installation sites of piston rings and around openings under a piston finger.
8. Pay attention to defects such as teases and attritions on a surface of a skirt, a hole in the bottom and progara on its edges. Strong damage of skirts of pistons testifies to frequent overheats of the engine, and also appear as a result of violation of correctness of process of combustion of air-fuel mix. It is necessary to check carefully a condition of components of lubrication systems and cooling. Teases on the side surfaces of pistons point to the admission of gases bypassing piston rings. Holes and progara in the bottoms of pistons are also signs of deviations in the course of mix combustion (too early ignition, a detonation, etc.). Anyway, in order to avoid a recurrence, the reasons of the revealed violations have to be defined and eliminated.

It is also necessary to check serviceability of functioning of the ignition/TNVD system and a condition of fuel nozzles.

9. Corrosion of pistons in the form of cavities demonstrates penetration of cooling liquid into combustion chambers and/or a case of the engine. The reason, besides, has to be established and eliminated.
10. On engines with the aluminum block and "wet" sleeves the possibility of replacement of pistons in an individual order is absent. Also new piston rings and sleeves of cylinders without fail are a part of a replaceable set (see Cleaning and check of a condition of the block of cylinders/case of the engine). For engines with the pig-iron block the set of new pistons can be ordered in service center of the Citroyon company.
11. Attentively check rods for existence of cracks around the top and lower heads. Estimate extent of deformation of crossing points of rods. The probability of damage of rods is very small if there was only no jamming and a strong overheat of the engine. Thorough check of a condition of rods can be made only in the conditions of a workshop of car service with use of the special diagnostic equipment.
12. On all engines before assembly it is necessary to make replacement of nuts and bolts of fastening of covers of the lower heads.
13. On all petrol engines piston fingers are put in the top head of rods внатяг therefore procedures of removal and installation of pistons have to be made by specialists of car repair shop at whose order there is the corresponding equipment. Track that in case of replacement of pistons replaceable answered on dimensional group to diameters of cylinders.

Developers of the car do not recommend to make dismantling of conrod and piston groups. In case of need you make replacement them assembled. It is not necessary to install the new piston on an old rod and vice versa.

14. On diesel engines piston fingers have floating landing and are fixed by lock rings. The procedure of removal of pistons from rods is described below.

15. Having hooked the small screw-driver with a flat sting, take lock rings.

16. Then push out a piston finger from assembly. For extraction of a finger there has to be quite enough moderate pressing a hand.

17. Put pistons together with the rods, - at assembly paired relationship should not be broken.

18. Attentively examine a piston finger and the top head of a rod on existence of signs of wear and damages. In case of strong wear the finger changes complete with the landing plug. Replacement of plugs demands use of a special press and lies outside qualification of the average amateur mechanic. The new plug it has to be accurately chamfered.
19. Need for replacement actually of rods can result from jamming of the engine. Try to estimate visually parallelism of an arrangement of the planes of heads of a rod. For more detailed check it is necessary to deliver rods in a workshop of car service.
20. Check a condition of all components, replaceable details should be ordered only in company service centers of the Citroyon company. New pistons are delivered complete with piston fingers and lock rings. However, a lock ring can be acquired also in an individual order.

21. At installation on a rod the piston have to it is developed by a cut in the bottom in that party in which grooves of inserts of the conrod bearing settle down. Before installation slightly oil a piston finger pure motive. Check freedom of rotation of the piston on a finger, then record the last lock rings. Track reliability of a zashchelkivaniye of lock rings in the landing flutes.