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
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
+ System of onboard electric equipment
+ Governing bodies and methods of operation
Check of compression pressure in cylinders
Check of compression 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 a possibility of definition of whether are the reason of falling of compression pressure of leak, 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 case of a head.
For conducting this check the engine has to be heated-up up to the normal working temperature, and the battery is completely charged.
- Begin with cleaning of candle niches (use compressed air, small or the simple bicycle pump). It will allow to avoid hit in the garbage engine at removal of spark plugs.
- Remove all spark plugs (The head Nastroyki and routine maintenance).
- Record a butterfly valve in completely open situation.
- Disconnect a coil wire from the central plug of a cover of the distributor and ground it on the engine case. For a guarantee of high-quality grounding use the wire equipped since both ends with a clip like "crocodile". Also it is necessary to put temporarily out of action a contour of the fuel pump (The head of the Power supply system and production of the fulfilled gases).
- Establish компрессометр in a candle opening of the first cylinder.
- It is preferable to use компрессометр not clamping type, and equipped with the carving nozzle rolled in a candle opening.
- 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 has to rise quickly. If low pressure on the first step is followed by gradual rise it 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 (also existence of cracks in casting of a head can be the reason). Often the excess nagaroobrazovaniye on plates of valves appears the reason of low compression pressure. Write down the maximum indication of a kompressometr.
- Repeat measurements for all remained cylinders and compare results to requirements of Specifications.
- Fill in in each of cylinders through its candle opening a little (about three teaspoons) motive oil and repeat check.
- If addition of oil led to normalization (increase) of compression pressure, then during initial check wear of piston rings is the reason of its low indications. If noticeable increase in pressure is not observed, leakages of valves or laying of a head 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.
- If pressure in two next cylinders is equally low, then 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 the existence of a cooler in combustion chambers or a case of the engine given the assumption.
- If pressure in one of cylinders differs from the others approximately for 20% and it is followed by insignificant violation of stability of turns of idling, it is necessary to check cams of final valves of the camshaft for existence of signs of wear.
- Unusually high compression pressure speaks about a possible strong nagaroobrazovaniye in combustion chambers. In this case it is necessary to remove also a head (i) and to carry out its decarbonization.
- Pressure drop or noticeable difference in different cylinders tells it about need of conducting check of the engine on leaks in the conditions of a workshop of car service. Such test will help to localize a source of leak and to estimate degree of gravity of defect.