4.2.1. Measurement of compression pressure and check of the engine on tightness
Check of compression pressure
|
It will be required special компрессометр for diesel engines. |
At decrease in efficiency of return of the engine, and also at emergence of admissions of ignition of mix which cannot be explained with malfunctions in a power supply system check of compression pressure in cylinders will help to define the general condition of the engine and to establish the reason of the violations taking place. Regular measurement of compression pressure allows to reveal beforehand and the developing malfunctions and to avoid the troubles connected with refusals of knots and systems of the car.
|
1. Check is made by means of the special kompressometr intended for measurement of a compression on diesel engines and calculated on high pressure. The measuring instrument is connected to the carving nozzle rolled an opening under installation of a glow plug or nozzle. On the considered models the nozzle under forsunochny openings in view of limitation of access to candle is required. It is hardly worth getting компрессометр in continuous use for conducting incidental checks, - it will be more reasonable to hire it, or to take measurements at car repair shop. |
|
2. Follow instructions of manufacturers of the device. In the absence of instructions it is necessary to take care of implementation of the following general requirements: a) The battery has to be in good repair and is completely charged, the engine - is heated-up up to the normal working temperature; b) All nozzles (or glow plugs) have to be turned out. At removal of nozzles do not forget to take also washers of flame arresters that the last were not beaten out by pressure developed in combustion chambers; c) The electromagnetic locking valve of shutdown of supply of fuel should be cut off power in order to avoid intake of fuel in cylinders and casual start of the engine. 3. During check there is no need to hold the accelerator pedal squeezed out as the air which is soaked up in the engine is not banished via the throttle camera. 4. The absolute value of the taken readings, how many uniformity of distribution of pressure between cylinders is important not so much (see Specifications). 5. The reason of decrease in compression pressure on diesel engines usually is established slightly more difficult, than on petrol. At the same time conducting "damp" check by a flood in cylinders of a small amount of oil does not yield desirable result in view of a high probability of leaving of oil in the vortex camera or in deepening in the piston bottom instead of filling of landing gaps of piston rings. 6. Pressure in all cylinders has to be almost identical. The difference in indications exceeding the value stipulated in Specifications should be considered as a violation sign. Remember that pressure in the serviceable engine has to rise quickly enough. The low indication on the first step with gradual increase it on the subsequent, speaks about wear of piston rings. If pressure does not rise at all, it is necessary to check tightness of closing of valves and a condition of laying of a head of cylinders (also the probability of formation of cracks in a head body is not excluded). The congestion of deposits on the lower surfaces of plates of valves can also cause loss of compression pressure. 7. Excessively high indications testify also development of a nagaroobrazovaniye on internal surfaces of a head of cylinders, valves and pistons. A head it is necessary to remove and make its decarbonization (see Removal and capital repairs of the engine). |
|
Check of the engine on leaks
During check exit speed from cylinders of the compressed air pumped in them is defined. This check is some kind of alternative to measurement of compression pressure. Moreover, from many points of view, it is much more effective as allows to reveal visually an air leak source that is often more evident, than interpretation of results of measurement of a compression.
Unfortunately, the equipment necessary for conducting check on leaks, is not among generally available therefore implementation of the procedure will be more reasonable to be charged to specialists of car service.