Jeep Grand Cherokee
+ Cars of mark Jeep Grand Cherokee
+ Options and routine maintenance
+ Рядный the six-cylinder engine
+ Engine V8
- Procedure of the general and engine major repairs
The general information
Engine major repairs - the general information
Check компрессионного pressure in cylinders
The diagnostic checks made by means of the vacuum gauge
Methods of removal of the engine and necessary safety measures
Removal and engine installation
Variants of restoration of the engine
Order of dismantling of the engine
Dismantling of a head of cylinders
Cleaning and check of a condition of a head of cylinders
Service of valves
Assemblage of a head of cylinders
Removal of shatunno-piston assemblages
Removal of a cranked shaft
Cleaning of the block of the engine
Check of a condition of the block of the engine
Хонингование cylinders
Check of a condition of shatunno-piston assemblages
Check of a condition of a cranked shaft
Check of a condition radical and шатунных bearings
Assembly order of the engine after end of its major repairs
Installation of a cranked shaft and check of backlashes of radical bearings
Installation of piston rings
Installation of shatunno-piston assemblages and check of backlashes in шатунных bearings
The first start of the engine after major repairs
+ Systems of cooling, heating and air conditioning
+ The power supply system and release of the fulfilled gases
+ System of an electric equipment of the engine
+ Systems of decrease in toxicity of the fulfilled gases and engine management
+ Manual box of a gear change
+ Automatic transmission
+ Distributing box
+ Coupling and трансмиссионная a line
+ Brake system
+ Suspension bracket and steering
+ Body
+ System of an onboard electric equipment
+ Controls and operation receptions
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Check of a condition of shatunno-piston assemblages
Before check of their condition shatunno-piston assemblages should be carefully cleared, and old rings are removed from pistons.
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At assemblage of the engine replacement of piston rings is made without fail. |
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By means of the special tool cautiously remove rings from pistons. Try not to damage in the course of performance of this procedure of a surface of pistons.
Scratch out traces of a deposit from a piston bottom. After removal of the basic layer of a deposit by a scraper, the remained traces can be removed by means of a manual wire brush or a thin emery paper. At all do not apply to this purpose wire nozzles on an electrodrill. Pistons are made of a soft material and their surface can be easily damaged.
By means of the special tool for procleaning of flutes under installation of piston rings remove from them traces of coal adjournment. In case of absence available the special tool for this purpose the fragment of an old piston ring perfectly will approach. Thus be careful - do not scratch out a material of the piston and do not damage a wall of flutes. Also protect fingers - the ring has very much keen edges.
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Flutes under installation of piston rings can be cleaned by means of the special tool, as is shown in the given picture.
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... Or by means of a fragment of an old piston ring - protect fingers.
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After removal of adjournment wash out shatunno-piston assemblages by solvent and dry their compressed air (if there is an access to its source). Make sure of passableness and cleanliness масловозвратных apertures in back walls of flutes under piston rings.
If pistons and mirrors of cylinders have no serious damages and are worn out in admissible limits, and the engine block was not given in проточку, necessity for replacement of pistons is absent. Normal deterioration of pistons is shown in the form of a uniform wipe of its persistent surfaces in a vertical direction and an easy weak point of landing in the flute of the top piston ring. However replacement of piston rings by the restored engine should be made without fail.
Carefully check up each piston on presence of cracks in a skirt, in lugs under piston fingers and around installation of rings.
Make sure of absence of scratches and задиров on persistent surfaces of skirts, apertures in the bottoms of pistons and прогаров their edges. Presence of such defects on skirts of pistons speaks about an overheat of the engine which probably took place during operation of the car and-or the wrong combustion of a mix causing excessive rise in temperature. Such pistons are subject to replacement. It is necessary to check up carefully a condition of components of systems of greasing and cooling. Apertures in the bottoms of pistons can be the certificate wrong поджига mixes (too early ignition). Edges Progary of the bottoms of pistons usually speak about a taking place detonation of a mix. In case of detection of any of the listed defects of the reason of their occurrence should be eliminated in order to avoid relapses at operation of the restored engine. The number of the reasons can include leaks of soaked up air, bad quality of a gas mixture, infringement of installation of a corner of an advancing of ignition and system refusal recycling the fulfilled gases (EGR).
Corrosion of pistons if she is shown in the form of small cavities, speaks about cooler hit in chambers of combustion and-or картер the engine. The reason again таки should be eliminated in order to avoid relapse.
Measure a lateral backlash of piston rings, serially putting rings in the flutes together with an edge (ями) probeа. Measurements make in several points on perimetre of the piston and watch conformity of a ring to a checked flute.
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Measure a lateral backlash of piston rings in several points of perimetre of the piston with the help probeа лезвийного type.
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Define a backlash between pistons and walls of cylinders by measurement at first diameters of cylinders (Section Check of a condition of the block of the engine), and then diameters of pistons. Make sure of conformity of pistons on the size to the cylinders. Diameter of the piston measure on a skirt in directions perpendicular and parallel to an axis of a piston finger. Subtract diameters of pistons from diameters of corresponding cylinders for definition of size of backlashes (люфтов). If results of calculations exceed admissible values under Specifications, the block should be given in проточку, and pistons and piston rings are replaced on corresponding the repair size.
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Measure diameter of the piston at an angle 90 to a piston finger and in parallel it.
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Check up a weak point of landing of the piston on a rod, having tried повращать them from each other in opposite directions. Any appreciable люфт speaks about excessive deterioration and demands situation correction. All works connected with replacement of pistons and rods and installation of new piston fingers are a prerogative of experts of a workshop of car-care centre.
If it is required to make removal of pistons from rods for any reason, the expert of a car repair shop should make this work. In parallel check of rods on presence of signs of a bend and twisting by means of the special equipment in the same place will be made.
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If product of replacement of pistons or rods is not required, to disconnect them from each other does not follow. |
Check up rods on presence of cracks and other damages. Temporarily remove covers of the bottom heads (шатунных bearings), take loose leaves, wipe подшипниковые surfaces in covers and rods and check up them on presence of agnails, задиров and scratches. After survey of rods establish into place old loose leaves, put on covers of bearings and tighten fixing nuts by hand.
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If engine restoration is made because of knock of rods, do not forget to replace them. |
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