Before going to the doctor, each of us is engaged in self-diagnosis. At the same time, we do not do x-rays for ourselves, we do not use an electrocardiograph and other sophisticated devices. We just feel the forehead, examine the throat, listen to see if it wheezes in the chest, if the lower back is twisted. Of the instruments, we traditionally use thermometers and, perhaps, a wrist watch when measuring the pulse.
This is how, in a simple way, we determine whether the body is functioning normally. And it does work!
The car engine is the same organism. For its accurate diagnosis and treatment, there are many complex devices, devices and tools. Various techniques and techniques are used that require a subtle knowledge of the internal structure. To begin with, we suggest that you master things that are easier to understand.
Let's try to figure out what you should pay attention to when operating a car: what you need to feel, where to look, where to listen and maybe even smell to understand how the engine feels. If you don’t want to study with us, take a hundred dollars out of your wallet and go to computer diagnostics. Automotive «medical service» paid!
Initial inspection
Imagine that you are a kind doctor. Entering the chamber (garage), approach the patient (car), be sure to say hello, tell him a few gentle, soothing words and offer to undress to the waist (open the hood). Start with an external inspection of the engine. Remember that nothing reflects inner well-being like a pleasant, well-groomed, healthy appearance.
Strong general contamination of the engine, as well as the presence of intense local leaks, on the contrary, indicates poor health. If in the evening, parting with the car, you prudently put a blank sheet of newspaper on the floor of the garage under the engine, take it out and inspect it. Traces of oil and other operating fluids overnight will leave traces on the newspaper, by which you can identify the sources of leaks and determine their intensity. The higher it is, the sooner you need to take corrective action.
The next step is to check and bring the levels of all operating fluids to the norm. We are primarily interested in engine oil and coolant (antifreeze), since their lack is most strongly reflected in the technical characteristics of the engine.
I would like to remind you that (trust me it's not a joke), to make sure there is fuel in the tank. Practice shows that some inattentive drivers almost to death torture the starter and battery, forgetting that before «well done» you need to feed and drink, and only then - on a shovel and into the oven.
At the same time, check the tension of the drive belts of the auxiliary engine units (coolant pump, alternator, power steering pump, air conditioner). Make sure the straps are not slack or broken. If everything is in order, dust off your pants and get behind the wheel.
Before starting the engine
Do not rush to immediately start the engine. There is no hurry here. First turn the key to position «ignition». As a rule, in this case, several control lamps light up on the instrument panel of all modern cars. At this stage, we are particularly interested in two: the first is a lamp for insufficient oil pressure in the lubrication system, the second is a warning lamp for the battery charge, which indicates the readiness of the generator to start working after starting the engine. Both lamps with the ignition on, even before starting the engine, should burn red. What if one of them doesn't light up? If the battery charge lamp does not light up, this is not so bad; if the lamp of insufficient oil pressure in the lubrication system does not light up, this is an alarm signal. Be careful, you have lost control of the lubrication system! The oil pressure in the engine is the main indicator of its serviceability. If you do not control the oil pressure, you are facing an engine overhaul with all the ensuing consequences.
The cause of the malfunction is either poor contact between the sensor connectors, or the sensor itself. Look for the sensor, as a rule, should be in the area of \u200b\u200bthe oil filter. The fault must be corrected. Only after you are convinced that everything is in order, start the engine.
«Cold» start
A serviceable engine with adjusted fuel supply and ignition systems, a serviceable battery starts on one attempt within 3–5 s. Persistent problems with «cold» start-up indicate a malfunction. Suppose we avoided this and the engine started.
We look at the instrument panel. The two lamps discussed above must go out.
Warning! If within 5 seconds the lamp of insufficient oil pressure in the lubrication system continues to burn, stop the engine!
After a few minutes, try starting the engine again. If there is no oil pressure, you need to look for the cause of the problem.
Possible reasons:
- low oil level;
- faulty oil pressure sensor;
- the grid of the oil receiver of the oil pump is clogged;
- the oil pump is faulty;
- large wear of the main and connecting rod bearings of the crankshaft.
If the oil pressure is normal, we proceed to examine the engine in the warm-up mode.
Engine warm-up
The cold engine speed is about 1.5 times the nominal engine speed at idle, which is typically 700–900 min-1 (rpm), and should gradually decrease as the engine temperature rises.
After 7–10 minutes from the start, the engine temperature should reach 80°C and stabilize (like idle speed).
This process is easy to control on the tachometer (engine speed measuring instrument) and coolant temperature gauge.
When the warm-up proceeds according to the above scenario, the idle system and the engine cooling system work normally.
If the engine temperature does not reach the desired level, the thermostat is most likely to blame (cooling system control valve). There are many more reasons for engine overheating, and they are reflected in the subsection of this manual that describes the engine cooling system.
After the engine has warmed up sufficiently and the idle speed has stabilized (you will know about it by readings of control devices), it's time to listen to how «sings» motor.
A beautiful voice is a healthy body
Doctors assure that in relation to a person this statement is completely true. The same can be said about the engine.
A good engine produces a steady hum and «ticking», like clockwork. Some masters say that he «whispers». Despite the figurative expressions, you probably understand what they mean.
If the engine runs unevenly, malfunctions, vibrates periodically, be aware that this is evidence of its malfunction. Sometimes malfunctions are the result of wear of engine parts and a drop in compression in the cylinders, but most often the causes are leaks in the intake tract, a clogged air filter, malfunctions of the ignition system and the power system (fuel supply).
I would like to dwell on those cases when the engine, as they say, «troit», i.e. one of the cylinders is not working.
With the help of a diagnostic device by the method of sequential disconnection of cylinders to find «saboteur» not difficult. As soon as you get to the faulty cylinder, the nature of the engine will not change.
Often the cause of a malfunction can be determined by examining the spark plug. This allows you to learn a lot of interesting things about the condition of the engine.
Not to mention extraneous noises and knocks. Let us immediately make a reservation that such a diagnostic method - «aerobatics», it is not even for all professionals.
Motorists should keep in mind that any sharp metallic sounds indicate a malfunction. If they «publish» mounted units (generator, pump (coolant pump), hydraulic booster) - this is half the trouble. Define «culprit» noise is possible if you sequentially remove the drive belts of these units. If, after removing the next belt, the extraneous sound disappears, shake the corresponding pulley to assess the value of the radial and axial play of the bearings. Most often, they are the troublemakers.
Much more trouble is threatened by knocks coming from the belly of the motor itself. They are listened to in various engine operating modes using an automobile stethoscope or, if one is not available, a dry stick with a diameter of about 10 mm made of hard wood (she is pressed to the cheekbone below the earlobe). In this way, it is possible to identify defects in the gas distribution mechanism, the cylinder-piston group, and the crank mechanism.
We emphasize once again: in order to make a diagnosis, musical ear is not enough, you need to have professional experience and excellent knowledge «materiel».
In a healthy body healthy mind
A diagnostic examination would be incomplete without an analysis of engine exhaust smoke. It is already warm enough, so it's time to go to the exhaust pipe and look at the horse «down the drain».
The exhaust of a serviceable engine is almost colorless. A barely perceptible light white smoke comes out of the exhaust pipe, the intensity of which increases when you sharply press the gas pedal.
In frosty weather, a serviceable car leaves rather thick clouds of white steam behind it (not to be confused with smoke!), indicating complete combustion of the fuel.
It is not necessary to inhale exhaust gases for a long time. We stop the engine. But it's not the end yet. It is worth examining the inner surface of the oil filler cap. The presence of traces of a foamy emulsion of a dirty yellow color on it is a very alarming symptom, indicating leakage of coolant into the lubrication system. After removing the expansion tank cap, inspect the appearance of the antifreeze.
Warning! To avoid injury (burn), Do this on a cold engine!
An oil film on the surface of antifreeze, as well as foamed engine oil, are harbingers of an imminent engine repair.
That, perhaps, is all. We have thoroughly examined «patient», literally «from nose to tip of tail». And during the inspection, they used not expensive equipment that was inaccessible to most motorists, but what was given to us by nature - sight, hearing, smell and, of course, the mysterious «gray matter».
Exhaust analysis
Oily belt 6-8 mm wide on the outer surface of the car exhaust pipe («mourning headband») due to increased oil consumption. Engine overhaul is inevitable.
Black smoke
Sign of incomplete combustion of fuel. The feed system prepares a very rich mixture and needs to be adjusted.
Blue smoke (purple) shade
Sign of increased oil consumption. The engine requires replacement of valve stem seals or repair of the cylinder-piston group.
Thick white smoke
A symptom of a burnt cylinder head gasket. Coolant enters the combustion chamber.
Smoke with the smell of exhaust gases from the removed pipe of the crankcase ventilation system (breather) engine.
A sign of a breakthrough of exhaust gases into the oil sump due to increased clearances in the cylinder-piston group.
A lot of «eating», but quietly rides
If the engine does not start well, pulls weakly and consumes a lot of fuel, the snag may not be what you first think about. A seemingly simple situation in terms of determining the root cause is the most insidious. Many bravely begin an independent search, not
realizing that these manifestations can be the result of a number of reasons, from elementary to quite serious. Well, if you have a car that uses simple and outdated technical solutions -classic «Zhiguli», «Moskvich» And «Volga» - you can safely contact auto mechanics with experience in the field of repairing such cars.
But, having changed the car to a more modern one, many motorists continue to turn to the same masters. And they do not have the courage to admit that they do not understand the complex processes that occur in fuel injection systems and electronic ignition circuits. They explore the spark «for breakdown», damaging the transistors, the insulation of the windings of the ignition coils, high-voltage wires and «blazing» conductive paths on covers and rotors of ignition distributors. Without solving the problem, such mechanics drive «disease» inside. And in the end, the owner still ends up with professionally trained mechanics. «Treatment» machines, however, will already be significantly hampered.
Specialists often find themselves in a situation where, after a long work, even with the use of complex instruments, they fail to understand anything. Only after some time (sometimes very long) it turns out that the previous master- «smart ass» changed the jets in the carburetor or twisted everything in the injection system, in the end violated its tightness or «killed» pressure meter.
The list of possible causes leading to increased fuel consumption and a decrease in engine power is very rich. And besides them, there are a number of uncharacteristic, but serious and quite common malfunctions, such as burnout of the piston, fuel getting into the oil, failure of one of the temperature sensors of the injection system and thermostat, entanglement of vacuum tubes, destruction of one of the carburetor gaskets, piston rings or piston baffles.
Diagnostics must be carried out without disassembly, since otherwise there is a great chance only to temporarily eliminate the consequence or even supplement the existing problem with a new one, sometimes more complex.
For example, there are a lot of reasons leading to a decrease in spark power. If the diagnosis is performed on a multifunctional motor tester, on its screen you can immediately determine which defect is taking place.
A common situation is when, having discovered signs of abnormal engine operation, a motorist goes to a mechanic. He, having measured the engine compression and found compliance with the norm, begins to regulate both the carburetor and the ignition system, achieving stable operation. Sometimes it succeeds. The engine starts up regularly, stops stalling, but at the same time, traction and fuel consumption leave much to be desired. Where is the mistake?
In a worn engine, valve seals often leak. The oil that gets on the pistons leads to artificial compensation of the gaps that have arisen during the wear of the pistons, rings and cylinders. As a result, when measuring compression, false readings are obtained. Fixing this problem after «repair», made by a mechanic, is significantly difficult due to the need to restore the original adjustments.
The reverse situation is also quite common, when the owner is unjustifiably «plunge» in a major overhaul, although it would be enough to replace the same seals, which is more than ten times cheaper.
Unfortunately, until now, the car maintenance market remains approximately equally divided into stations that meet modern requirements for qualifications, technical and cultural services, and fragments of the sadly memorable Soviet car service. Therefore, car owners should carefully familiarize themselves with the technical center on the pit of which the car will be installed. And not so much with the cost of services, but with how, with what and under what conditions they will diagnose and repair the car.