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

The diagnostic checks made by means of the vacuum gage

Measurement of depth of depression gives valuable information on a condition of internal components of the engine. There is a possibility to estimate degree of wear of piston rings and walls of cylinders, to reveal leakages of a head of cylinders and the inlet pipeline, violation of passableness of system of production of the fulfilled gases, jamming or a burn-out of valves, weakening of klapanny springs, violation of installation of a corner of an advancing of ignition or distribution of operation of valves, and other problems with ignition.

Unfortunately results of vacuum testing are easily wrong for interpreting, therefore it always should be made together with other checks, the general which analysis of results allows to draw unequivocal conclusions.

For adequate assessment of the situation are important both absolute indications of the vacuum gage, and relative size of a deviation of an arrow of the device. The majority of vacuum gages measure depth of depression in mm (inches) of a mercury column (all results and indicators are lower will be given in metric system). All given below the reference become on the basis of the assumption of carrying out check at zero height concerning a sea level. Lifting of a point of carrying out check (or decrease in atmospheric pressure) conducts to the corresponding decrease in instrument readings. For a binding we will note that the increase in height of a point of carrying out tests at each meter after a mark of 610 m gives result understating on 83 mm of mercury.

Connect the vacuum gage directly to the entrance union of the inlet pipeline - not to port of the case of a throttle. Track, that no hoses during check remained disconnected is will lead to violation of reliability of results.

Before starting check let's to the engine be warmed up completely. Block (wedges) of a wheel and cock the parking brake. Having transferred transmission to the situation "R", start the engine and leave its working at turns of normal idling.

Before starting the engine attentively examine fan blades on existence of cracks and other damages. Watch that during performance of procedure not to touch the fan and not to allow contact to it vacuum hoses. After start of the engine it is not necessary to become directly in front of the car or in the plane of rotation of the fan.

Consider vacuum gage indications; for the reference, on the average, the serviceable engine should create depression by depth from 431 to 559 mm of mercury. At the stable provision of an arrow of the device. Results of check can are interpreted as follows:


  1. The stable low indication of the vacuum gage usually speaks violation of integrity of laying between the inlet pipeline and the throttle case, existence of "leakages" of vacuum hoses, delay of the moment of ignition or violation of distribution of operation of the klapanny mechanism (camshaft). By means of a stroboscope check installation of a corner of an advancing of ignition, then carry out all diagnostic checks listed in this Chapter before starting removal of a cover of a distributive chain and check of correctness of combination of distributive labels.
  2. If instrument readings are lower than norm on 75-200 mm of mercury. also are unstable at this level, the probability of existence of leaks through laying of the inlet pipeline around an arrangement of inlet port or malfunction of an injector of fuel is great.
  3. If the arrow of the device regularly falls on 75-100 mm of mercury., stably keeping on these values, it is possible to suspect leakage of valves. Make check of kompressionny pressure or testing of the engine for leaks.
  4. Irregular falling or deviations of an arrow can be caused by jamming of the valve or ignition admissions. Make check of kompressionny pressure or testing of the engine for leaks, also check spark plugs.
  5. Frequent trembling of an arrow at level about 100 mm of mercury. at operation of the engine on the single turns, accompanied by the filled with smoke exhaust speaks about wear of directing plugs of valves. For confirmation of this assumption make testing of the engine for leaks. If trembling arises at increase of turns of the engine, check on leaks laying of the inlet pipeline or a head of cylinders, estimate extent of weakening of klapanny springs, whether make sure valves burned through and whether take a place ignition admissions.
  6. Insignificant fluctuations within 25 mm up-down can testify to existence of problems with ignition. Make all usual settings, in case of need start the engine for work with the ignition analyzer.
  7. In case of an essential deviation make check of kompressionny pressure or testing of the engine for leaks for check of degree of wear or failure of cylinders or violations of integrity of laying of a head.
  8. If the arrow of the vacuum gage slowly "walks" in a wide range, whether check the system of operated ventilation of a case (PCV) is corked, estimate quality of a fuel and air mix and also check on existence of signs of leakages of laying of the case of the throttle/carburettor and the inlet pipeline.
  9. Make check on slow recovery of indications after engine "revival" by fast opening of a butterfly valve and an otpuskaniye her ambassador of lifting of frequency of rotation of a cranked shaft in 2500 rpm. Usually indications should fall practically to zero, rise above norm (approximately by 130 mm of mercury.) and then to return to former value. If depth of depression is restored slowly and does not form peak when closing butterfly valve, it is possible to speak about wear of piston rings. If the considerable delay takes place, check passableness of system of production of the fulfilled gases (often it appears is blocked the exhaust silencer or the catalytic converter). Such assumption is simplest for checking having disunited sections of system of production of the fulfilled gases above a place of prospective obstruction.