Remove a head of the block of cylinders, a flywheel, the oil pallet, the oil pump and a maslozaborny branch pipe.
Remove a ledge in the top part of the cylinder, formed as a result of wear.
If rods and covers of rods are not marked, mark them.
Fig. 2.2. Piston and rod: 1top kompressionny ring; 2bottom kompressionny ring; 3maslosjemny ring; 4piston; 5piston finger; 6rod; 7bolt of fastening of a cover of a rod; 8top shatunny loose leaf; 9bottom shatunny loose leaf; 10-rod cover; 11-nut of fastening of a cover of a rod
Establish pistons (fig. 2.2)
of the first and fourth cylinders in the bottom dead point.
Unscrew fixing nuts, uncover the first rod and the bearing loose leaf, mark loose leaves.
Put on pieces of a rubber tube shatunny bolts not to injure a neck of a cranked shaft and a cylinder wall at removal of pistons assembled with rods.
Remove loose leaves of bearings and take a rod from above from the block through a cylinder opening.
Remove similarly other rods and pistons.
Dismantling and assembly of pistons with rods
Fig. 2.3. The adaptation for dismantling and assembly of pistons with rods
Dismantling and assembly of pistons with rods is recommended to be carried out by means of the adaptation 09234-33001 for engines in working volume of 1,1/1,3 l and the adaptation 09234-3302 for engines in working volume of 1,5/1,6 l. The adaptation for dismantling and assembly of pistons with rods is shown on
Check of a technical condition
Pistons and piston fingers
Check pistons on existence , scratches and other defects. Replace defective pistons.
Check all piston rings on existence of chips, damages and strong wear. Replace defective rings. At replacement of the piston replace also a piston finger.
Be convinced of lack of an excessive gap between a piston finger and piston lugs. Replace the defective piston assembled with a finger. The piston finger should enter smoothly into piston lugs by pressing a hand (at room temperature).
Check a gap between piston rings and the corresponding flutes of the piston. If the gap exceeds maximum permissible value in operation, establish in a flute a new ring and again check a gap between a ring and a flute. If the gap again exceeds maximum permissible value, replace the piston and rings. If the gap does not exceed maximum permissible value, replace only piston rings.
Nominal gap between a ring and a flute, mm:
top kompressionny ring:
engine of 1,3 l..... 0,040,085
engine of 1,1 l..... 0,030,07
bottom kompressionny ring:
engine of 1,3 l..... 0,040,085
engine of 1,1 l..... 0,020,06
The maximum permissible gap
for the top and bottom kompressionny rings makes 0,1 mm.
For gap check in the lock of a ring insert a ring into the cylinder. Establish a ring at right angle to a cylinder axis, having slightly pressed it the piston. Check a gap in the lock of a ring (tab. 2.1) the shchupy. If the gap exceeds maximum permissible value, the ring is subject to replacement.
Gap in the ring lock
Top kompressionny ring:
engine of 1,3 l
engine of 1,1 l
Bottom kompressionny ring:
engine of 1,3 l
engine of 1,1 l
At replacement of rings without boring of cylinders the gap in the lock of a ring 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 gap in the lock and their marking:
Nominal Not marked
0,25 mm............ 25
0,50 mm............ 50
0,75 mm............ 75
1,0 mm............. 100
Marking is 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 of shatunny 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 wear, and also at a strong roughness of a working surface of an opening in the top head of a rod.
Installation of piston rings
The maslosjemny ring is established to the first. At first establish in a flute a dilator, then establish the bottom and top maslosjemny rings.
After installation of all elements of a maslosjemny ring check, that the top and bottom rings rotated freely, without jammings.
Establish the bottom kompressionny ring a label up.
Then establish the top kompressionny ring.
With rotation of kompressionny rings dissolve their locks as it is possible further one from another, watching that they did not appear in one plane with locks of disks of a maslosjemny ring 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 compliance 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
Wear of tsilindroporshnevy group
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 : in it constantly there are processes of dying off of old cages and replacement their 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 wear, an engine resource before major maintenance, as well as durability of all car as a whole, in many respects depend on that, how qualitatively it is made and is competently maintained.
The main details of the engine pistons with piston rings, rods and cylinders are especially subject to wear. Operation of pistons of the engine most impresses. After all, moving the returnable it 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
and a piston stroke, say, 75 mm the total way overcome by the piston in a 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 h in day, excepting days off (that, of course, it is improbable for the average car), the piston will overcome distance of 460 km. At intensive operation of the car in 5 years (namely such duration of operation of the car before major maintenance of the engine is confirmed by statistics) the piston will cover distance of 24 000 km!
So, wear of the piston and details interfaced to it (the engine cylinder) is inevitable. However values of wear of piston group (pistons - piston rings) before major maintenance for engines of various firms very strongly differ from each other. So, limiting wear 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 others, say, less perfect models, need replacement of pistons and piston rings after 50 000 km of run (almost in 10 times less).
In what here 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. Let's remind first of all that pressure of gases in cylinders of these engines at the beginning of a working course differs approximately twice. In the petrol engine carburetor or with direct injection of fuel it makes 4055 kg/cm
, in a diesel engine
. Therefore also 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 aluminum alloy and covered outside with a tin layer 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 kompressionny rings and one maslosjemny are placed. The lower part of the piston a skirt in cross-section section oval, and on height of a conic form: in the top part diameter is less, than in the bottom. Besides, in piston lugs with openings under a piston finger there are two steel thermoregulating inserts. All this is made for prevention of increase in a friction between a skirt and a cylinder mirror when heating piston. At smaller, than at aluminum, factor of thermal expansion these inserts pull together a skirt in the direction, perpendicular axes of a piston finger.
Opening under a piston finger in modern engines usually displace from an axis of symmetry of the piston to the right side of the engine. For the correct assembly of the piston with a rod and their installations in the engine cylinder about an opening of a lug there is a label which should be turned towards a forward part of the engine. Such shift do for reduction of 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 openings for giving of a stream of oil on the loaded party of a mirror of the cylinder (in some engines these openings are absent) are executed. Loose leaves and a cover of the bottom head of a rod are also supplied with the corresponding labels for the correct assembly. Its further working capacity and durability essentially depends on accuracy of manufacturing of the piston and its true selection to a cylinder opening. Leading engine-building firms apply today system according to which pistons on external diameter are broken usually into five or six classes with a step of 0,01 mm. Except
that, they are divided into three or four categories with a step of 0,004 mm according to diameter of an opening 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 opening in lugs and to a rod. For the major maintenance of engines consisting usually in boring (increase in diameters) cylinders, producers of spare parts let out so-called repair pistons of the increased sizes.
The piston of a modern diesel engine is calculated on perception of 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 placement of the chamber of combustion directly in a piston head. As combustion of a toplivovozdushny mix occurs when finding the piston near 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 kompressionny rings are established. In the bottom flutes two maslosjemny rings are placed. Many firms produce kompressionny rings of rectangular section, practically nothing different from rings of petrol engines. However more progressive, though more expensive, the design with a konusny top working surface of a ring is. A tilt angle forming a cone at such rings do usually equal 10 . Application of konusny rings provides some increase in their durability as during a working course the component of pressure force of gases on a konusny surface of a ring in addition presses it to a cylinder mirror. Feature of service and repair of pistons with konusny kompressionny rings is need of exact control of gaps. Gaps between a flute and maslosjemny rings supervise the same as in petrol engines.
Forces of a friction between surfaces of a skirt of the piston and a cylinder mirror at diesel engines are higher, than in petrol engines. For increase in durability at a surface of a skirt of pistons put a layer of a special colloidal and graphite covering. It much more improves a piston prirabatyvayemost to the cylinder and increases term of its work before major maintenance. Similar processing of rubbing surfaces of pistons apply today and on petrol engines.
Except wear of surfaces of a skirt, flutes of kompressionny rings of pistons wear out also. Also the flute of a maslosyemny ring though such wear usually is much less Besides, wears out. At wear of flutes of a ring of the piston start to move more and more intensively down and up 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 of engine oil. Getting to the combustion chamber, oil burns down there, forming a gray smoke which leaves an exhaust pipe of the car. At considerable wear of flutes replacement of rings on new improves a situation a little. There comes objective need for replacement of all piston group, boring of cylinders till the repair size is thus very desirable. All described types of wear is natural and, unfortunately, inevitable process.
Nevertheless this natural wear can be stretched in time, prolonging thus engine service life. Here it is not necessary to open America. Simply it is necessary to fulfill precisely requirements of the producer for car operation, to use qualitative engine oil and oil filters, it is correct to regulate fuel equipment. Use of high-quality modifiers of oil and fuel, the preparations changing a microstructure of blankets of surfaces of a friction of engines gives good results.
Along with it wear of the engine, as well as all car as a whole, in many respects depends on the driver, from his qualification and technical literacy. After all not for nothing cars of the same brand at one drivers serve long and smoothly, at others are under repair almost every week. The skilled driver almost never allows operation 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 which is usually accompanied by a booming sound of low tone on lowered frequency of rotation of a cranked shaft. Mode of dispersal of the car also
it is accompanied by the increased wear 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 dashingly, extremely sharply to disperse the car. But, if such abrupt style of driving becomes a habit, repair of the engine will be provided twice earlier, than is provided by specifications.
Other type of wear not provided by any instructions is often observed also. It is emergency breakage of elements shatunno? piston group and first of all rings and crossing points of ring flutes of the piston. In petrol engines it is connected first of all with a detonation. Let's remind that the detonation is a vzryvopodobny combustion of a toplivovozdushny mix in the cylinder, accompanied by spasmodic increase of pressure in the combustion chamber. It is to equivalently sharp blow 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. Detonation reasons a little. However main of them this operation of the engine on gasoline with lower, than it is provided by specifications, octane number, and also an overheat and work on the reenriched gas mixture. The skilled driver is obliged to hear detonation knocks at operation of the engine and immediately to reduce supply of fuel at dispersal, and then to eliminate the detonation reasons. A sound of a detonation 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 supply 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 is certainly inadmissible. To continue movement in such mode it is equivalent to a razbivaniye a hammer of interiors of the engine.
Diesel engines are not so sensitive to change of composition of fuel, though in them there are the troubles conducting to increased wear of details of the krivoshipno-shatunny mechanism. It first of all overheat of the engine and related reduction of viscosity of oil, especially if quality of oil the low. The increased wear can be also a consequence of the wrong adjustment of the fuel pump of a high pressure and deterioration of dispersion of fuel in combustion chambers because of violation of work of nozzles. And, certainly, a lot of things depends on the driver.
So, from everything 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 manufacturing firm, and level of technical operation for which the driver finally answers answers. It is necessary to remember it both upon car purchase, and by preparation and training of drivers.