Remove a head of the block of cylinders, a flywheel, the oil pallet, the oil pump and маслозаборный a branch pipe.
Remove a ledge in the top part of the cylinder, formed as a result of deterioration.
If rods and covers of rods are not marked, mark them.
Fig. 2.2. The piston and a rod: 1 – top компрессионное a ring; 2 – bottom компрессионное a ring; 3 – маслосъемное a ring; 4 – the piston; 5 – a piston finger; 6 – a rod; 7 – a bolt of fastening of a cover of a rod; 8 – top шатунный the loose leaf; 9 – bottom шатунный the loose leaf; 10 – a rod cover; 11 – a nut of fastening of a cover of a rod
Establish pistons (fig. 2.2) the first and fourth cylinders in the bottom dead point.
Turn away fixing nuts, uncover the first rod and the bearing loose leaf, mark loose leaves.
Put on pieces of a rubber tube on шатунные bolts not to damage a neck of a cranked shaft and a cylinder wall at removal of pistons in gathering with rods.
Remove loose leaves of bearings and take a rod from above from the block through a cylinder aperture.
Remove similarly other rods and pistons.
Dismantling and assemblage of pistons with rods
Fig. 2.3. The adaptation for dismantling and assemblage of pistons with rods
Dismantling and assemblage of pistons with rods is recommended to be spent by means of the adaptation 09234-33001 for engines in working volume of 1,1/1,3 l and adaptations 09234-3302 for engines in working volume of 1,5/1,6 l. The adaptation for dismantling and assemblage of pistons with rods is shown on fig. 2.3.
Check of a technical condition
Pistons and piston fingers
Check up pistons on presence задиров, scratches and other defects. Replace defective pistons.
Check up all piston rings on presence having chopped off, damages and strong deterioration. Replace defective rings. At piston replacement replace also a piston finger.
Be convinced of absence of an excessive backlash between a piston finger and piston lugs. Replace the defective piston in gathering with a finger. The piston finger should enter smoothly into piston lugs by pressing by a hand (at a room temperature).
Check up a backlash between piston rings and corresponding flutes of the piston. If the backlash exceeds maximum permissible value in operation, establish in a flute a new ring and again check up a backlash between a ring and a flute. If the backlash again exceeds maximum permissible value, replace the piston and rings. If the backlash does not exceed maximum permissible value, replace only piston rings.
Nominal backlash between a ring and a flute, mm:
Top компрессионное a ring:
The engine of 1,3 l..... 0,04–0,085
The engine of 1,1 l..... 0,03–0,07
Bottom компрессионное a ring:
The engine of 1,3 l..... 0,04–0,085
The engine of 1,1 l..... 0,02–0,06
The maximum permissible backlash for top and bottom компрессионных rings makes 0,1 mm.
For backlash check in the ring lock insert a ring into the cylinder. Establish a ring at right angle to a cylinder axis, slightly having pressed it the piston. Check up a backlash in the lock of a ring (tab. 2.1) щупом. If the backlash exceeds maximum permissible value, the ring is subject to replacement.
Backlash in the ring lock
The ring name
Top компрессионное a ring:
The engine of 1,3 l
The engine of 1,1 l
Bottom компрессионное a ring:
The engine of 1,3 l
The engine of 1,1 l
At replacement of rings without расточки cylinders the backlash in the ring lock needs to be checked, having established a ring in the bottom, less worn out part of the cylinder. It is necessary to replace rings with rings of the same dimensional group.
Dimensional groups of piston rings on a backlash in the lock and their marks:
Nominal Not marked
0,25 mm............ 25
0,50 mm............ 50
0,75 mm............ 75
1,0 mm............. 100
Marks are put on the top surface of a piston ring.
Installation of covers of rods make according to numbers of cylinders put on covers at dismantling.
At installation of a new rod watch that adjusting dredging шатунных loose leaves settled down on the one hand.
Always replace rods with damage of one of the surfaces which are exposed to axial loading. Replace rods in the presence of layered deterioration, and also at a strong roughness of a working surface of an aperture in the top head of a rod.
Installation of piston rings
By the first it is established маслосъемное a ring. At first establish in a flute a dilator, then establish bottom and top маслосъемные rings.
After installation of all elements маслосъемного rings check up, that the top and bottom rings rotated freely, without jammings.
Establish bottom компрессионное a ring a label upwards.
Then establish top компрессионное a ring.
With rotation компрессионных rings dissolve their locks as it is possible further one from another, watching that they have not appeared in one plane with locks of disks маслосъемного rings and a piston finger.
Compress piston rings by means of the adaptation and insert the piston into the cylinder.
At installation of covers of rods watch conformity of numbers put on rods and their covers at dismantling. Be convinced that labels on pistons and rods at installation (identification labels) are turned towards a forward part of the engine.
At installation of new rods watch that adjusting dredging of loose leaves settled down on the one hand.
Useful data and councils
Deterioration цилиндропоршневой groups
The car engine sometimes compare to heart of the person. Really, it works constantly while the car moves. However, such comparison is not quite correct. After all heart, as well as any live organism, is continuous самовосстанавливается: in it constantly there are processes of dying off of old cages and their replacement new, young. That you will not tell in any way about the lifeless mechanism – the automobile engine. It, despite all our diligence, wears out is almost irreversible. However intensity of such deterioration, a resource of the engine before major repairs, as well as durability of all car in whole, in many respects depend on that, is how much qualitative it is made and competently maintained.
The main details of the engine – pistons with piston rings, rods and cylinders are especially subject to deterioration. Work of pistons of the engine most impresses. After all, moving it vozvratno-is forward between the top and bottom dead points, they cover huge distance. So, at
To frequency of rotation of a cranked shaft of 5000 mines-1 and a piston stroke, say, 75 mm the total way overcome by the piston in minute, makes 375 m. For an engine business hour this distance will make 2 km of 250 m, and for a month of operation on 8 ч in day, excluding days off (that, of course, is improbable for the average car), the piston will overcome distance of 460 km. At intensive operation of the car for 5 years (namely such duration of operation of the car before engine major repairs is confirmed with statistics) the piston will cover distance of 24 000 km!
So, deterioration of the piston and details interfaced to it (the engine cylinder) is inevitable. However values of deterioration of piston group (ring pistons-piston) before major repairs for engines of various firms rather strongly differ from each other. So, limiting deterioration of pistons and piston rings of engines Mercedes-Benz, Volkswagen, BMW, the majority of the American and Japanese firms comes after run about 300 000 km.
At the same time engines of other, say, less perfect models, require replacement of pistons and piston rings already after 50 000 km of run (almost in 10 times less).
In what here the reason? And how the durability of these details depends on service conditions? For the answer to these questions we will consider two typical designs of piston groups of the petrol engine and a diesel engine. We will remind first of all that pressure of gases in cylinders of these engines in the beginning of a working course differs approximately twice. In the petrol engine – carburettor or with direct injection of fuel it makes 40–55 kg/sm 2, in a diesel engine –
70–80 kg/sm 2. Therefore and pistons of petrol and diesel engines differ one from another though the main constructive decisions at them are identical.
The typical piston of the petrol engine is cast from an aluminium alloy and covered outside by a layer of tin for improvement extra earnings to a cylinder mirror. Diameter of its top part – heads – on 0,1 mm is less, than internal diameter of the cylinder. It is made for prevention of jamming of a head of the piston in the cylinder at a warming up to working temperature. In ring flutes of the piston two are placed компрессионных rings and one маслосъемное. The bottom part of the piston – a skirt – in cross-section section oval, and on height of the conic form: in the top part diameter is less, than in the bottom. Besides, in lugs of the piston with apertures under a piston finger there are two steel thermoregulating inserts. All it is made for prevention of increase in a friction between a skirt and a cylinder mirror at piston heating. At smaller, than at aluminium, factor of thermal expansion these inserts pull together a skirt in a direction, perpendicular axes of a piston finger.
Aperture under a piston finger in modern engines usually displace from an axis of symmetry of the piston in the right party of the engine. For correct assemblage of the piston with a rod and their installations in the cylinder of the engine about a lug aperture there is a label which should be turned towards a forward part of the engine. Such displacement do for reduction of a lateral making pressure force of the gases pressing the piston to one of the parties of the cylinder during a working course.
The rod also should be correctly focused in the engine. On its forward party apertures for giving of a stream of oil on the loaded party of a mirror of the cylinder (in some engines these apertures are absent) are executed. Loose leaves and a cover of the bottom head of a rod also are supplied by corresponding labels for correct assemblage. Its further working capacity and durability essentially depends on accuracy of manufacturing of the piston and its true selection to a cylinder aperture. Leading engine-building firms apply today system according to which pistons on external diameter are broken usually into five or six classes with step of 0,01 mm. Except
That, they are divided into three or four categories with step of 0,004 mm according to diameter of an aperture under a piston finger. Engine cylinders also have similar division into five classes. Such system allows to pick up more precisely the piston to any, even to the worn out cylinder, and a piston finger of the necessary category – to an aperture in lugs and to a rod. For the major repairs of engines consisting usually in расточке (increase in diameters) cylinders, manufacturers of spare parts let out so-called repair pistons of the increased sizes.
The piston of a modern diesel engine is calculated on perception more high pressures, therefore the thickness of its bottom and lugs is more. Besides, the design of the piston of a diesel engine differs from considered above a little. The main difference is placing of the chamber of combustion directly in a piston head. As combustion топливовоздушной mixes occurs at a finding of the piston near to the top dead point, hot gases heat up a piston head more strongly, and walls of the top part of the cylinder heat up slightly less, than in petrol engines. For reliable consolidation of the piston in the cylinder on its external surface five flutes for installation of piston rings are made. In three top flutes are established компрессионные rings. In the bottom flutes two are placed маслосъемных rings. Many firms produce компрессионные rings of rectangular section, practically nothing different from rings of petrol engines. However more progressive though also more expensive, the design with конусной the top working surface of a ring is. An angle of slope forming a cone at such rings do usually equal 10 °. Application конусных rings provides some increase in their durability as during a working course a component of a pressure force of gases on конусную the ring surface in addition presses it to a cylinder mirror. Feature of service and repair of pistons with конусными компрессионными rings is necessity of the exact control of backlashes. Backlashes between a flute and маслосъемными rings supervise the same as in petrol engines.
Forces of a friction between surfaces of a skirt of the piston and a mirror of the cylinder at diesel engines above, than in petrol engines. For increase in durability at a surface of a skirt of pistons put a layer of a special kolloidno-graphite covering. It much more improves прирабатываемость the piston to the cylinder and increases term of its work before major repairs. Similar processing of rubbing surfaces of pistons apply today and on petrol engines.
Except deterioration of surfaces of a skirt, flutes компрессионных rings of pistons wear out also. Also the flute маслосьемного rings though such deterioration usually considerably is less Besides, wears out. At deterioration of flutes of a ring of the piston start to move more and more intensively downwards and upwards on height of a flute and more and more notable there is a so-called pump action of rings. This action is shown in more and more increasing expense by the engine oil engine. Getting to the combustion chamber, oil burns down there, forming a grey smoke which leaves an exhaust pipe of the car. At considerable deterioration of flutes replacement of rings on new improves a situation a little. There comes objective necessity for replacement of all piston group, is thus rather desirable расточка cylinders till the repair size. All described kinds of deterioration is natural and, unfortunately, inevitable process.
Nevertheless this natural deterioration can be stretched in time, продливая thus engine service life. Here it is not necessary to open America. Simply it is necessary to fulfil precisely requirements of the manufacturer on car operation, to use qualitative engine oil and oil filters, correctly to regulate fuel equipment. Good results are given by application of qualitative modifiers of oil and fuel, the preparations changing a microstructure of blankets of surfaces of a friction of engines.
Along with it deterioration of the engine, as well as all car in whole, in many respects depends on the driver, from its qualification and technical literacy. After all knowingly cars of the same mark at one drivers serve long and smoothly, at others – are under repair almost every week. The skilled driver almost never supposes works of the engine with an overload, and furthermore with a detonation. He constantly listens, as the engine of its car works, and immediately reacts to any overload usually accompanied by a booming sound of low tone on lowered frequency of rotation of a cranked shaft. A mode of dispersal of the car also
It is accompanied by the raised deterioration of the engine. The analogy to a horse and the equestrian Here arises: the careful owner without special need will not whip the canine friend, forcing it to run straight away, especially when the horse was not warmed up yet. Certainly, in critical situations the driver presumes to disperse the car dashing, extremely sharply. But, if such abrupt style of driving becomes a habit, engine repair will be provided twice earlier, than is provided by specifications.
Other kind of deterioration not provided by any instructions is frequently observed also. It is emergency breakage of elements шатунно? Piston group and first of all rings and crosspieces of ring flutes of the piston. In petrol engines it is connected first of all with a detonation. We will remind that the detonation is взрывоподобное combustion топливовоздушной mixes in the cylinder, accompanied by spasmodic increase of pressure in the combustion chamber. It is to equivalently sharp blow by a sledge hammer on the motionless piston and rings. Details, naturally, are not calculated on such loading and can break, having damaged then the splinters a cylinder mirror. The reasons of a detonation a little. However main of them – this work of the engine on gasoline with lower, than it is provided by specifications, октановым number, and also an overheat and work on the reenriched gas mixture. The skilled driver is obliged to hear detonation knocks at work of the engine and immediately to reduce fuel giving at dispersal, and then to eliminate the detonation reasons. A detonation sound are the metal clicks of a high-pitch tone coinciding on frequency with frequency of rotation of a cranked shaft. They can be hardly audible against other sounds of the working engine, especially at slightly early ignition, and vanish at absolutely insignificant reduction of giving of fuel (gas). Such hardly appreciable detonation testifies to correctly adjusted coal of an advancing of ignition, but happens and so that detonation knocks appear at once by pressing an accelerator pedal that, certainly, is inadmissible. To continue movement in such mode equivalently разбиванию a hammer of interiors of the engine.
Diesel engines are not so sensitive to change of structure of fuel though and in them there are the troubles conducting to raised deterioration of details krivoshipno-shatunnogo of the mechanism. It first of all an overheat of the engine and the reduction of viscosity of oil connected with it, especially if quality of oil the low. The raised deterioration can be also a consequence of wrong adjustment of the fuel pump of a high pressure and deterioration of dispersion of fuel in chambers of combustion because of infringement of work of atomizers. And, certainly, much depends on the driver.
So, from all told it is possible to draw such conclusions. The durability of the engine of your car, as well as all vehicle as a whole, depends on two factors: qualities of manufacturing for which the firm-manufacturer, and level of technical operation for which the driver finally answers answers. It is necessary to remember it both at car purchase, and by preparation and training of drivers.