The general information and diagnostic operations are provided in this subsection for definition of a condition of the engine.

It is not always easy to come to a conclusion about expediency of complete major maintenance of the engine as it is necessary to be based on a number of objective indicators.

Big run is not a sufficient indicator of need of carrying out major maintenance, on the other hand, small run does not exclude need of carrying out major maintenance. The most important indicator, most likely, is timeliness of the current maintenance of the engine. At timely change of oil and the filter, and also at performance of all other necessary works on service the engine serves reliably throughout many thousand kilometers of run. On the contrary, insufficient on volume or untimely maintenance can be at the bottom of sharp reduction of a resource of the engine.

The raised consumption of oil indicates wear of the piston rings, directing plugs of valves and maslootrazhatelny caps. It is necessary to be convinced that leaks are not at the bottom of the raised consumption of oil, and only after that to draw a conclusion about unfitness of piston rings and directing plugs of valves. to define a probable cause of malfunction, measure a compression in engine cylinders. Carry out also tests by means of the vacuum gage and define character of indications of this device.

Check pressure of oil a manometer screwed instead of the sensor of pressure of oil, and compare result of check to standard value. If pressure of oil low, the reason can be wear of radical and shatunny bearings or details of the oil pump.

Capacity loss, failures in operation of the engine, a detonation or the metal knocks, the increased noise from the gas-distributing mechanism, indicate the increased fuel consumption need of carrying out major maintenance, especially, if all these signs of abnormal work are shown at the same time. If performance of all adjustments does not lead to improvement, the unique means of elimination of abnormal operation of the engine is major maintenance. Major maintenance consists in restoration of details of the engine to a condition specified in specifications for the new engine.

At carrying out major maintenance pistons and piston rings are replaced, chiseled or хонингуются cylinders. After repair of cylinders which is carried out in a specialized workshop, installation of pistons of the repair sizes is required. Shatunnye and radical loose leaves of a cranked shaft, and also a cover of basic necks of camshafts also are subject to replacement, if necessary follows прошлифовать necks of a cranked shaft before restoration of normal gaps with shatunny and radical loose leaves. As a rule, valves, as their condition at the moment of repair, as a rule, not the absolutely satisfactory are subject to repair also.

During major maintenance of the engine repair of such units as a starter, the generator and the ignition distributor also is carried out. As a result repaired engine should possess qualities of the new unit and sustain considerable run without refusals.

At major maintenance it is necessary to replace such important details of system of cooling as hoses, drive belts, the thermostat and the pump of cooling liquid. The radiator should be surveyed on tightness and purity of internal channels. If you got the restored engine, or the block of cylinders of an incomplete complete set, some suppliers do not give a guarantee on operation of these units without high-quality washing of a radiator. At major maintenance of the engine also it is recommended to replace the oil pump.

Before the beginning of major maintenance of the engine familiarize with the description of the corresponding procedures that there was an impression of the forthcoming amount of works and requirements to them. At observance of all norms and rules, in the presence of all necessary tools and adaptations it is simply to execute major maintenance, considerable expenses of time however be required. Roughly not less than two weeks, especially are required if for repair and restoration of details it is necessary to address in a specialized workshop. Check existence of spare parts and in advance take care of acquisition of necessary special tools and the equipment. Almost all works can be executed by means of a standard tool kit though more exact measuring devices will be necessary for check and determination of suitability of these or those details. Often check of a condition of details carry out in specialized workshops in which also receive recommendations about replacement or restoration of these or those details.

It should be noted that assembly of units should be carried out with all care in a pure room to avoid further failures of the repaired engine and to provide its reliable work.