5.1. The general data
In the given part of Chapter 2 the order of performance of such works as dismantle of the power unit from the car and major repairs of details of the internal device of considered engines is in detail considered. Recommendations about check of a condition of various details have the general character.
Engine major repairs - broad-brush observations
It is not always easy to come to a conclusion about expediency of full major repairs of the engine as it is necessary to be based on variety of objective indicators.
The big run is not a sufficient indicator of necessity of carrying out of major repairs, on the other hand, small run does not exclude necessity of carrying out of major repairs. The most important indicator most likely is timeliness of current maintenance service 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 kilometres of run. On the contrary, insufficient on volume or untimely maintenance service can be at the bottom of sharp reduction of a resource of the engine.
The raised expense of oil specifies in deterioration of the piston rings, directing plugs of valves and маслосъемных caps. It is necessary to be convinced that leaks are not at the bottom of the raised expense of oil, and only after that to do a conclusion about unfitness of piston rings and directing plugs of valves. To define a malfunction plausible reason, measure a compression in engine cylinders (section 2 see).
For scoping of forthcoming works check up a compression in engine cylinders (section 4 see). Conduct also tests by means of the vacuum gauge and define character of indications of this device (section 3 see).
Check up pressure of oil a manometre screwed to the place of the gauge of pressure of oil and compare result of check to standard value. If pressure of oil low deterioration radical and шатунных bearings or details of the oil pump can be the reason.
Capacity loss, "failures" in engine work, a detonation or the metal knocks, the raised noise from газораспределительного the mechanism, specify the raised expense of fuel in necessity of carrying out of major repairs, especially, if all these signs of abnormal work are shown simultaneously. If performance of all adjustments does not lead to improvement unique means of elimination of abnormal work of the engine are major repairs. Major repairs consist in restoration of details of the engine to a condition specified in specifications for the new engine. At major repairs carrying out pistons and piston rings are replaced, chiseled or хоннингуются cylinders. After repair of cylinders which is carried out in a specialised workshop, installation of repair pistons is required. Шатунные and radical loose leaves коленвала, and also covers of basic necks of a cam-shaft also are subject to replacement, if necessary follows прошлифовать necks коленвала before restoration of normal backlashes with шатунными and radical loose leaves. As a rule, valves, as their condition at the moment of repair as a rule not absolutely satisfactory are subject to repair also. During engine major repairs 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 repairs it is necessary to replace such important details of system of cooling as hoses, drive belts, the thermostat and the pump of a cooling liquid. The radiator should be surveyed on tightness and cleanliness of internal channels (Gl see. 3). If you have bought the repair engine, or the block of cylinders of an incomplete complete set some suppliers do not give a guarantee on operation of these units without qualitative washing of a radiator. At engine major repairs also it is recommended to replace the oil pump.
Before the beginning of major repairs of the engine familiarise with the description-corresponding of procedures that there was an impression of forthcoming amount of works and requirements to them. At observance of all norms and rules, in the presence of all necessary tools and adaptations, major repairs to execute simply, considerable expenses of time however be required. Roughly it is required not less than two weeks, especially if for repair and restoration of details it is necessary to address in a specialised workshop. Check up presence 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 tooling though exact measuring devices will be necessary for check and definition of suitability of those or other details. Frequently check of a condition of details carry out in specialised workshops in which also receive recommendations about replacement or restoration of those or other details.
To address in car-care centre workshops follows only after full dismantling of the engine and check of a condition of all details, especially the block of cylinders to solve which operations on service and repair will be carried out in workshops.
As the condition of the block of cylinders is the defining factor of decision-making on its further repair or about purchase new (or repair) the block of cylinders to buy spare parts or to carry out operations on machining of accompanying details follows only after careful check of its technical condition. Make it a rule that the true price of repair is time, - then it is not necessary to pay for installation of the worn out or restored details.
In summary we will notice that assemblage of any units should be carried out with all carefulness in a pure premise to avoid the further refusals of the repaired engine and to provide its reliable work.
Diagnostics of the engine by means of the vacuum gauge
Depression measurement is reliable and rather cheap way of diagnostics of the engine. Under vacuum gauge indications it is possible to receive representation about a condition of piston group, about tightness of linings of a head of the block of the cylinders which are soaking up and final collectors, correctness of adjustments of the power supply system of the engine and release of the fulfilled gases, throughput of the fulfilled gases, a condition of valves (them залипании or a burn-out) and springs of valves and also to check up correctness of adjustment of the moment of ignition and preservation of phases timing at engine work.
Unfortunately, vacuum gauge indications are difficult for interpreting and results of the analysis of indications can be erroneous, therefore, vacuum diagnostics expediently to unite with other methods.
Initial factors on which indications of the vacuum gauge are analyzed and the most exact conclusions about an engine condition become, the absolute instrument reading and character of movement of an arrow of the device (dynamics of indications) are. A scale of the majority of vacuum gauges проградуирована in mm. рт. A column. In process of depression increase (and accordingly pressure drop) the instrument reading increases. On each 300 m above sea level absolute indications of the vacuum gauge will differ approximately on 25 mm Hg
Attach the vacuum gauge directly to a soaking up collector (Sm, a photo), but not to other apertures through which the vacuum, by the channel of certain length separated from a collector (for example, to apertures before throttle заслонкой) is created.
Before the beginning of tests completely warm up the engine. Block wheels and put the car on a manual brake. At position of the lever of a gear change in neutral position (or in position Park on cars with automatic transmission) start the engine and leave to idle.
Before engine start carefully check up a condition of blades of the fan (presence on them of damages or cracks). In an operating time of the engine do not bring a hand too close to the fan, hold the device on sufficient removal from the fan and do not stand on one line with rotating крыльчаткой.
Check up the vacuum gauge indication. On the serviceable engine the vacuum gauge should show depression of 430-560 mm Hg, and the arrow of the device should be almost motionless.
More low the description of character of indications of the vacuum gauge and a technique of definition of a condition of the engine on their basis follows.
1. Too low level of depression usually specifies on not tightness of a lining between a soaking up collector and the chamber throttle заслонки, a vacuum hose, and also in too later ignition or for the wrong moment of opening and closing of valves. Before removing covers of a gear belt and to check up combination of adjusting labels check up installation of ignition by means of a stroboscope and eliminate all other possible reasons, being guided by the techniques of check described in the present Chapter.
2. If vacuum gauge indications on 75 - 200 mm Hg below normal also are unstable (the arrow twitches) it specifies in a leak in a lining on an input of a soaking up collector or on malfunction of an atomizer.
3. If the arrow regularly deviates on 50 - 100 mm Hg the reason is not tightness of valves. For acknowledgement of this conclusion check up a compression in engine cylinders.
4. The arrow irregularly deviates towards low indications, or shaking shows low depression. A plausible reason is the raised resistance to movement of valves, or faults in work of cylinders. Check up a compression in cylinders and examine candles.
5. If idling the arrow quickly fluctuates within 100 mm Hg, and engine work is accompanied by a smoke from the muffler directing plugs of valves are worn out. For check of this conclusion it is necessary to conduct tests of chambers of combustion for tightness (with air rating). If the arrow quickly fluctuates and the increase in turns of the engine it is necessary to check up tightness of a lining of a soaking up collector, elasticity of springs of valves is simultaneously observed. Such indications also can be caused a burn-out of valves and faults in work of cylinders (ignition failures).
6. Weak fluctuations of an arrow (within 20-30 mm Hg in both parties) specify in unstable work of ignition. Check up all provided installations and adjustments, if necessary connect to the engine the analyzer of system of ignition.
7. At the big fluctuations of an arrow check up a compression in cylinders, or conduct tests for tightness as causes of defect can be the idle cylinder, or infringement of tightness of a lining of a head of cylinders.
8. If instrument readings slowly vary in a wide range check up cleanliness of pipelines of system of compulsory ventilation картера, correctness of adjustment of a gas mixture, tightness of linings of the case throttle заслонки, or a soaking up collector.
9. Sharply open throttle заслонку and when engine turns will reach 2500 rpm release заслонку. Заслонка should come back slowly in a starting position. Vacuum gauge indications should fall almost to zero, then increase and exceed the control indications corresponding to stationary idling approximately on 125 mm Hg then depression should be restored at former level. If depression is restored slowly, and at sharp opening заслонки excess of the control indication is absent, the reason deterioration of piston rings can be. At the slowest restoration of depression check up cleanliness of a final path (as a rule the muffler or каталитического the converter). The most simple way of such check consists in disconnection of an exhaust path before a suspicious site and in test repetition.