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 kompressionny pressure in cylinders

Check of kompressionny pressure in cylinders can give valuable information on the general mechanical condition of the top part of the engine (pistons, piston rings, valves, laying of heads of cylinders). Special value has possibility of definition of, whether are the reason of falling of kompressionny pressure the leaks caused by wear of piston rings or defects of valves and their saddles, or the reason lies in violation of integrity of laying or the head case.

For carrying out this check the engine should be heated-up to normal working temperature, and the battery is completely charged.


  1. Begin with cleaning of candle niches (use the compressed air, small or the simple bicycle pump). It will allow to avoid hit in the garbage engine at removal of spark plugs.
  2. Remove all spark plugs (Head of Control and routine maintenance).
  3. Fix a butterfly valve in completely open situation.
  4. Disconnect a coil wire from the central plug of a cover of the distributor and earth it on the engine case. For a guarantee of high-quality grounding use a wire equipped since both ends with a clip of the crocodile type. Also it is necessary to put temporarily out of action a contour of the fuel pump (Head of the Power supply system and production of the fulfilled gases).
  5. Establish компрессометр in a candle opening of the first cylinder.
  1. It is preferable to use компрессометр not clamping type, and equipped with the carving nozzle rolled in a candle opening.
  1. Turn the engine, having carried out pistons at least through seven steps of compression, reading out instrument readings. Pressure in the cylinder of the serviceable engine should rise quickly. If low pressure on the first step is accompanied by its gradual lifting during the subsequent, it testifies to an unsuccessful condition of piston rings. Low pressure on all steps speaks about leakages of valves or defect of laying of a head of cylinders (the reason existence of cracks in head molding can be also). The superfluous nagaroobrazovaniye on plates of valves appears often reason of low kompressionny pressure. Write down the maximum indication компрессометра.
  2. Repeat measurements for all remained cylinders and compare results to requirements of Specifications.
  3. Fill in in each of cylinders through its candle opening a little (about three teaspoons) impellent oil and repeat check.
  4. If addition of oil led to normalization (increase) of kompressionny pressure, the reason of its low indications during initial check is wear of piston rings. If appreciable increase of pressure it is not observed, leakages of valves or head laying take place. Leakages of valves can be caused by a burn-out of their saddles and/or deformation of working surfaces of facets, and also a bend of cores of valves or formation of cracks in plates.
  5. If pressure in two next cylinders is equally low, it is very strong argument in favor of existence of violation of integrity of a crossing point of laying of a head between them. Will confirm this assumption cooler existence in chambers of combustion or an engine case.
  6. If pressure in one of cylinders differs from the others approximately for 20 % and it is accompanied by insignificant violation of stability of turns of idling, it is necessary to check cams of final valves of a camshaft on existence of signs of wear.
  7. Unusually high kompressionny pressure speaks about a possible strong nagaroobrazovaniye in combustion chambers. In this case it is necessary to remove and a head (and) and to carry out its (their) dekarbonizatsiya.
  8. Pressure drop or appreciable difference in different cylinders tells it about need of carrying out check of the engine on leaks in the conditions of a car-care center workshop. Such test will help to localize a source of leak and to estimate degree of gravity of defect.