Jeep Grand Cherokee

1993-1999 of release

Repair and car operation

Jeep Grandee Cheroki
+ Jeep Grand Cherokee brand Cars
+ Settings and routine maintenance
+ Ryadny six-cylinder engine
+ V8 Engine
- Procedures of the general and major maintenance of the engine
   General information
   Major maintenance of the engine - the general information
   Check of kompressionny pressure in cylinders
   The diagnostic checks made by means of the vacuum gage
   Methods of removal of the engine and necessary precautionary measures
   Removal and engine installation
   Options 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
   Assembly of a head of cylinders
   Removal of shatunno-piston assemblies
   Removal of a cranked shaft
   Cleaning of the block of the engine
   Check of a condition of the block of the engine
   Honingovaniye of cylinders
   Check of a condition of shatunno-piston assemblies
   Check of a condition of a cranked shaft
   Check of a condition of radical and shatunny bearings
   Engine assembly order after completion of its major maintenance
   Installation of a cranked shaft and check of gaps of radical bearings
   Installation of piston rings
   Installation of shatunno-piston assemblies and check of gaps in shatunny bearings
   The first start of the engine after major maintenance
+ Systems of cooling, heating and air conditioning
+ the Power supply system and production of the fulfilled gases
+ System of electric equipment of the engine
+ Systems of decrease in toxicity of the fulfilled gases and engine management
+ Manual box of gear shifting
+ Automatic transmission
+ Transfer case
+ Coupling and transmission line
+ Brake system
+ Suspension bracket and steering
+ Body
+ System of onboard electric equipment
+ Governing bodies and operation receptions

Check of a condition of shatunno-piston assemblies

Before check of their condition shatunno-piston assemblies should be carefully cleared, and old rings are removed from pistons.

At engine assembly replacement of piston rings is made without fail.


  1. By means of the special tool carefully remove rings from pistons. Try not to damage in the course of performance of this procedure of a surface of pistons.
  2. Scratch out deposit traces from a piston bottom. After removal of the main 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.
  3. By means of the special tool for pro-cleaning of flutes under installation of piston rings remove from them traces of coal deposits. In case of absence available the special tool the fragment of an old piston ring perfectly will be suitable for this purpose. 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 keen edges.
  1. Flutes under installation of piston rings can be cleaned by means of the special tool, as is shown in this picture.

... or by means of a fragment of an old piston ring - protect fingers.

  1. After removal of deposits wash out shatunno-piston assemblies by solvent and dry them the compressed air (if there is an access to its source). Make sure of passableness and purity of maslovozvratny openings in back walls of flutes under piston rings.
  2. If pistons and mirrors of cylinders have no serious damages and are worn-out in admissible limits, and the block of the engine was not sent to a pro-point, need for replacement of pistons is absent. Normal wear of pistons is shown in the form of a uniform wipe of its persistent surfaces in the vertical direction and an easy weak point of landing in the flute of the top piston ring. However replacement of piston rings on the restored engine should be made without fail.
  3. Carefully check each piston on existence of cracks in a skirt, in lugs under piston fingers and around installation of rings.
  4. Make sure of absence of scratches and задиров on persistent surfaces of skirts, openings in the bottoms of pistons and прогаров their edges. Existence 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 temperature increase. Such pistons are subject to replacement. It is necessary to check carefully a condition of components of systems of greasing and cooling. Openings in the bottoms of pistons can be the certificate of the wrong ignition of a mix (too early ignition). Progara of edges 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 emergence should be eliminated in order to avoid recurrence at operation of the restored engine. The number of the reasons can include leakages of soaked-up air, bad quality of gas mixture, violation of installation of a corner of an advancing of ignition and refusal of system of a retsirkulyatsiya of the fulfilled gases (EGR).
  5. Corrosion of pistons if it is shown in the form of small cavities, speaks about cooler hit in chambers of combustion and/or an engine case. The reason again should be eliminated in order to avoid recurrence.
  6. Measure a lateral gap of piston rings, serially putting rings in the flutes together with an edge (hole) щупа. Measurements make in several points on perimeter of the piston and watch compliance of a ring to a checked flute.
  1. Measure a lateral gap of piston rings in several points of perimeter of the piston with the help щупа lezviyny type.
  1. Define a gap between pistons and walls of cylinders by measurement at first diameters of cylinders (The section Check of a condition of the block of the engine), and then diameters of pistons. Make sure of compliance of pistons on the size to the cylinders. Diameter of the piston measure on a skirt in the directions perpendicular and parallel to an axis of a piston finger. Subtract diameters of pistons from diameters of the corresponding cylinders for determination of size of gaps (люфтов). If results of calculations exceed admissible values according to Specifications, the block should be given to a pro-point, and pistons and piston rings are replaced on corresponding the repair size.
  1. Measure diameter of the piston at an angle 90 ° to a piston finger and parallel to it.
  1. Check 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 wear 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 center.
  2. If it is required to make removal of pistons from rods for any reason, the specialist of car repair shop should make this work. In parallel in the same place check of rods on existence of signs of a bend and twisting by means of the special equipment will be made.

If work of replacement of pistons or rods is not required, to disconnect them from each other does not follow.

  1. Check rods on existence of cracks and other damages. Temporarily remove covers of the bottom heads (shatunny bearings), take loose leaves, wipe bearing surfaces in covers and rods and check them on existence 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.

If restoration of the engine is made because of knock of rods, do not forget to replace them.