Jeep Grand Cherokee

1993-1999 of release

Repair and operation of the car

Jeep Grand Cherokee
+ Cars of the Jeep Grand Cherokee brand
+ Settings and routine maintenance
+ Line six-cylinder engine
+ V8 engine
- Procedures of the general and capital repairs of the engine
   General information
   Capital repairs of the engine - the general information
   Check of compression 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 installation of the engine
   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 conrod and piston assemblies
   Removal of a bent 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 conrod and piston assemblies
   Check of a condition of a bent shaft
   Check of a condition of radical and conrod bearings
   Engine assembly order after completion of its capital repairs
   Installation of a bent shaft and check of gaps of radical bearings
   Installation of piston rings
   Installation of conrod and piston assemblies and check of gaps in conrod bearings
   The first start of the engine after capital repairs
+ Cooling systems, heating and air conditioning
+ A 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 methods of operation

Check of a condition of conrod and piston assemblies

Before check of their state conrod and piston assemblies have to be carefully cleared, and old rings are removed from pistons.

At assembly of the engine 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 implementation 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 a scraper, the remained traces can be removed by means of a manual wire brush or a thin emery paper. Do not apply to this purpose wire nozzles on the electric drill at all. Pistons are manufactured of soft material and their surface can be easily damaged.
  3. By means of the special tool for a clearing of flutes under installation of piston rings remove from them traces of coal deposits. In case of lack available of the special tool the fragment of an old piston ring perfectly will be suitable for this purpose. At the same time be careful - do not scratch out 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 shown in this picture.

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

  1. After removal of deposits wash out conrod and piston assemblies by solvent and dry them compressed air (if there is an access to its source). Make sure of passability 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 given 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 has to be made without fail.
  3. Carefully check each piston for existence of cracks in a skirt, in lugs under piston fingers and around installation of rings.
  4. Make sure of absence of scratches and zadir on persistent surfaces of skirts, openings in the bottoms of pistons and progar of their edges. Existence of such defects on skirts of pistons speaks about an overheat of the engine which perhaps took place during operation of the car and/or the wrong combustion of mix causing excessive temperature increase. Such pistons are subject to replacement. It is necessary to check carefully a condition of components of lubrication systems and cooling. Openings in the bottoms of pistons can be the evidence of the wrong ignition of mix (too early ignition). Progara of edges of the bottoms of pistons usually speak about the mix detonation taking place. In case of detection of any of the listed defects of the reason of their emergence have to be eliminated in order to avoid a recurrence at operation of the restored engine. Leak of the soaked-up air, bad quality of gas mixture, violation of installation of a corner of an advancing of ignition and failure of the system of recirculation of the fulfilled gases (EGR) can be among the reasons.
  5. Corrosion of pistons if it is shown in the form of small cavities, speaks about hit of a cooler in combustion chambers and/or a case of the engine. The cause has to be besides removed in order to avoid a recurrence.
  6. Measure a side gap of piston rings, serially putting rings in the flutes together with a probe edge(s). You perform measurements in several points on perimeter of the piston and you watch compliance of a ring to the checked flute.
  1. Measure a side gap of piston rings in several points of perimeter of the piston by means of the probe of lezviyny type.
  1. Define a gap between pistons and walls of cylinders by measurement at first of diameters of cylinders (Section Check of a Condition of the Block of the Engine), and then diameters of pistons. Make sure of compliance of pistons by the size to the cylinders. Measure diameter of the piston 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 (side plays). If results of calculations exceed values, admissible on Specifications, the block has to be sent 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 to rotate them from each other in opposite directions. Any noticeable side play speaks about excessive wear and demands correction of a situation. 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 service.
  2. If it is required to make removal of pistons from rods for any reason, the specialist of car repair shop has to perform 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 performing replacement of pistons or rods is not required, it is not necessary to disconnect them from each other.

  1. Check rods for existence of cracks and other damages. Temporarily uncover the lower heads (conrod bearings), take inserts, wipe bearing surfaces in covers and rods and check them for existence of agnails, zadir and scratches. After survey of rods establish into place old inserts, 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.