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 there is a squeak in the chest, if the stomach swells, 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 tricky devices, devices and tools. Various precise methods and techniques are used, requiring a subtle knowledge of the internal structure. We plan to talk about them in detail in the near future.
To begin with, we suggest mastering easier-to-understand things.
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 placed a blank sheet of newspaper under the engine, take it out and inspect it. Leaks 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 level 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 - believe me, I'm not joking - that you need to make sure that there is fuel in the tank. Practice shows that some inattentive drivers almost to death torture the starter and battery, forgetting that first the young man needs to be fed and watered, and only then - on a shovel and into the oven.
At the same time, check the tension of the drive belts of the mounted 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 trousers 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, at the same time, a row of bulbs lights up on the instrument panel of all modern cars. At this stage, we are particularly interested in two.
The first is an emergency oil pressure lamp, the second is a battery charge warning lamp, which indicates the readiness of the generator to start working after starting the engine. Both should glow bright red with the ignition on before starting the engine. What if one of them doesn't light up? If the recharging lamp does not light up, this is not so bad, but if the emergency oil pressure lamp does not light up, this is alarming "bell". Be careful, you have lost control of the lubrication system! The oil pressure in the engine is the main indicator of the health of the unit. If you don't control the oil pressure, you risk "fuck" overhaul of the engine with all the ensuing consequences.
The cause of the malfunction is either poor terminal-sensor contact, or the sensor itself. Look for the sensor, as a rule, should be in the area of the oil filter. The fault must be corrected. Only after you have made sure that everything is in order, start the engine.
"Cold" start
A serviceable engine with well-adjusted fuel and ignition systems and a healthy battery starts on one attempt within 3-5 seconds. 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 lights mentioned above must go out.
Attention: if within 5 sec. The oil pressure light stays on, 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 in order, we proceed to examine the engine in the warm-up mode.
Engine warm-up
The cold engine speed is approximately 1.5 times the rated idle speed, which is typically 700-900 rpm, and should gradually decrease as the engine temperature rises.
After 7–10 minutes from the start, the engine temperature should reach a level of about 80°C and stabilize (like idle).
If your car is equipped with a tachometer and a pointer instrument that shows the temperature of the coolant, this process is easy to control.
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 valve is most likely to blame. There are many more reasons for engine overheating and they are reflected in the technical certificate.
After the engine has warmed up sufficiently and the idle speed has stabilized (you will learn about it from the readings of control devices), it's time to listen to the motor sing.
Beautiful, sonorous voice - 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, know that this indicates a malfunction. Sometimes problems 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, and malfunctions of the ignition and fuel systems. I would like to dwell on those cases when the engine, as they say, "troit", that is, one of the cylinders does not work.
Using the method of alternately disconnecting high-voltage wires from spark plugs, 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 is "aerobatics" and not all professionals can do it.
Motorists should keep in mind that any sharp metallic sounds indicate a malfunction. If they "publish" mounted units (generator, pump, hydraulic booster) - this is half the trouble. Define "culprit" noise is possible by sequentially removing the drive belts of these units. If, after removing the next belt, the extraneous sound disappears, shake the corresponding pulley to determine 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 a car stethoscope or, if it is not available, with a dry stick with a diameter of about 10 mm made of hardwood (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 that in order to make a diagnosis, musical ear is not enough, you need to have professional experience and excellent knowledge "materiel".