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Overview
In this part of Chapter 2 details the order of execution of such works as the dismantling of the power unit from the car and repair the internal details of the engines under consideration. Recommendations for checking the status of various parts of a general nature.
Engine Overhaul - general comments It is not always easy to come to a conclusion about the advisability of a complete engine overhaul, as necessary based on a number of objective indicators. The big run is not a sufficient indicator of the need for major repairs, on the other hand, small run does not exclude the need for major repairs. The most important indicator most likely is timeliness of current maintenance of the engine. At timely change of oil and filter, as well as the implementation of all other necessary works on service, the engine serves reliably throughout many thousand kilometers. On the contrary, insufficient on volume or untimely maintenance can cause a sharp reduction in engine life. Increased consumption of oil specifies in deterioration of piston rings, valve guides and valve stem seals. Make sure that the leak did not cause increased oil consumption, and only after that to do a conclusion about unfitness of piston rings and valve guides. In order to determine the probable cause of the fault, measure the cylinder compressions (see. Section 2). To determine the amount of work, check the cylinder compressions (see. Section 4). Spend as tested using a gauge and define the nature of the indications of this device (see. Section 3). Check the oil pressure gauge screwed into place the oil pressure sensor and compare the test result with the standard value. If the oil pressure is low, the cause may be the wear of indigenous and connecting rod bearings or parts of the oil pump. Power loss, "failures" in engine work, a detonation or the metal knocks, increased noise from the timing, increased fuel consumption point to the need for major repairs, especially if all these signs of abnormal work are shown simultaneously. If performance of all adjustments does not improve, then the only way to eliminate the abnormal operation of a motor overhaul. Overhaul is to restore parts of the engine to a condition specified in the technical data for the new engine. During the overhaul replaced pistons and piston rings, chiseled or Honningbrew cylinders. After repair of cylinders, which is carried out in a specialized workshop, installation of repair pistons is required. Rods and radical loose crankshaft, as well as covers of basic necks of a cam must also be replaced, if necessary, should be abraded neck crank to the restoration of normal backlashes with rods and indigenous inserts. As a general rule, subject to repair and valves, as their condition at the time of repair is generally not quite satisfactory. During engine overhaul and repair of such units is carried out as a starter, the generator and the ignition distributor. As a result repaired engine should possess the qualities of the new unit and sustain considerable run without failure.
Comment. When overhaul is necessary to replace such important details as the cooling system hoses, drive belts, the thermostat and water pump. The radiator should be surveyed on tightness and cleanliness of internal channels (see. Ch. 3). If you bought the repair engine, or the engine block is missing, that some providers do not give a guarantee for the operation of these units without qualitative washing of a radiator. At engine major repairs also it is recommended to replace the oil pump.
Before starting an engine overhaul, check the description of the relevant procedures, make an impression of forthcoming amount of works and requirements to them. Subject to all rules and regulations, with all the necessary tools and devices, Repair is simple to perform, but will require a significant investment of time. Roughly it is required not less than two weeks, especially if for repair and restoration of details will have to address in a specialized workshop. Check the availability of spare parts and in advance take care of acquisition of necessary special tools and equipment. Almost all the work can be performed using a standard set of tools, but to test and determine the suitability of those or other details need precise measuring instruments. Often the inspection of the parts is carried out in specialized workshops in which also receive recommendations about replacement or restoration of those or other details.
Comment. Contact the service center workshops follows only after full dismantling of the engine and check the status of all the details, especially the cylinder block to decide which operations on service and repair will be carried out in workshops.
Since the state of the cylinder block is a determining factor in making a decision on its further repair or purchase of a new (or maintenance) of the cylinder, then to buy spare parts or 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 - did not have to pay for the installation of used or reconditioned parts. In conclusion, the assemblage of any units should be carried out with great care in a clean room to avoid further refusals of the repaired engine and to ensure reliable operation.
Diagnostics of the engine with the help of the gauge Measurement of dilution is reliable and relatively cheap way to diagnose the engine. According to the testimony of the gauge can get an idea about the state of the piston group of tightness gaskets of the cylinder head, intake and exhaust manifold, the correct adjustment of the power of the engine and the exhaust capacity of the exhaust gas condition of valves (them is stuck or burning) and valve springs, as well as check the correct adjustment of the moment of ignition and preservation of phases timing during engine operation. Unfortunately, the gauge readings are difficult to interpret and analyze the results of readings may be erroneous, therefore, vacuum diagnostics it is advisable to combine with other methods. Initial factors on which the gauge readings are analyzed and made the most accurate conclusions about the state of the engine is the absolute instrument reading and character of movement of the instrument pointer (dynamics of indications). Most gauges Scale is scaled in millimeters. Hg. column. With increasing dilution (and accordingly pressure drop) the instrument reading increases. For every 300 m above sea level absolute indications of the vacuum gauge will vary by approximately 25 mm. Hg. Art. Attach gauge directly to the intake manifold (see, pictures), but not to other openings through which a vacuum is separated from the manifold channel of a certain length (for example, before the throttle openings). Before the beginning of tests completely warm up the engine. Block the wheels and set the parking brake. When you position the gear lever in neutral (or in position Park on cars with automatic transmission) start the engine and leave to idle.
A warning. Before starting the engine, carefully check the condition of the fan (presence on them of damages or cracks). During operation, the motor does not bring your hands too close to the fan, hold the device at a sufficient distance from the fan, and do not stand in line with the rotating impeller.
Check the gauge. On the serviceable engine the gauge should show a vacuum of 430 -560 mm. Hg. Art., and the arrow of the device should be almost motionless. The following is a description of the nature of the vacuum gauge readings and methodology for determining the condition of the engine based on them. 1. Too low vacuum level usually indicates no seal between the suction manifold and the throttle chamber, a vacuum hose, as well as too late or incorrect ignition time of opening and closing valves. Before removing the cover of a gear belt and check the combination of adjusting labels check up installation of ignition by a stroboscope and eliminate all other possible causes, guided test procedures described in this chapter. 2. If the gauge readings at 75 - 200 mm. Hg. Art. below normal and are unstable (the arrow twitches) it indicates a leak in the lining of the inlet suction manifold or a faulty injector. 3. If the arrow regularly deviates by 50 - 100 mm. Hg. Art., the cause is not the tightness of the valve. To confirm this conclusion, check the engine compression. 4. The arrow irregularly deviates towards low indications, or twitching shows low depression. The probable cause is the increased resistance to movement of valves, or disruptions in the cylinder. Check the compression in cylinders and examine candles. 5. If idling the arrow quickly fluctuates within 100 mm. Hg. Art., and engine work is accompanied by smoke from the muffler, the worn valve guides. To verify this conclusion, it is necessary to conduct tests of chambers of combustion for tightness (with air pump). If the arrow quickly fluctuates at the same time an increase in engine speed, it is necessary to check the tightness of the intake manifold gasket, elasticity of the valve springs. Such evidence may also be caused by a burn-out of valves and faults in work of cylinders (ignition failures). 6. Weak fluctuations of the arrow (in the range of 20-30 mm. Hg. Art. In both directions) indicate an unstable work of ignition. Check out all the provided installation and adjustment, if necessary, connect the analyzer to the engine ignition system. 7. For large fluctuations arrow check up a compression in the cylinders, and tested for leaks, as reasons for failure can be broken cylinder or infringement of tightness of the cylinder head gasket. 8. If readings slowly vary over a wide range, check the cleanliness of pipelines PCV, correct adjustment of the fuel mixture, the hermetic seal of the throttle body or intake manifold. 9. Sharply open throttle, and when the engine speed is reached in 2500 rev / min release valve. The damper should slowly return to starting position. Gauge readings should fall almost to zero, then increase and exceed the control indications corresponding to stationary idling approximately 125 mm. Hg. st., then depression should be restored at the same level. If depression is restored slowly, and at sharp opening valves controlling excess evidence is missing, the reason may be the wear of piston rings. At extremely slow restoration of depression check up cleanliness of a final path (as a rule the muffler or catalytic converter). The easiest way to check this is the opening of the exhaust duct to the suspicious areas and to repeat the test.
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