Contents: Initial examination ↓ Before starting the engine ↓ "Cold" start ↓ Warming up the engine ↓ A beautiful, sonorous voice means a…↓
Is everything OK with the car engine? Maybe it's time to put money aside for computer diagnostics, or even repairs? A few tips from an auto engineer who has been repairing imported cars for many years will help you answer these questions.
Before going to the doctor, each of us does self-diagnosis. We do not do X-rays, do not use an electrocardiograph or other fancy devices. We simply feel our forehead, examine our throat, listen to see if there is a sizzle in our chest, a bloated stomach, or a cramp in our lower back. Of the devices, we traditionally use thermometers and, perhaps, a wristwatch when measuring our pulse.
This is how, in simple terms, we determine whether the body is functioning normally. And it works!
A car engine is the same organism. There are many tricky devices, gadgets and tools for its precise diagnostics and treatment. Various precise methods and techniques are used, requiring a subtle knowledge of the internal structure. We plan to tell about them in detail in the near future.
To begin with, we suggest mastering things that are easier to understand.
Let's try to figure out what to pay attention to when operating a car: what to touch, where to look, where to listen and maybe even smell to understand how the engine feels. If you don't want to learn with us, take a hundred dollars out of your wallet and go to a computer diagnostics. Automobile "medical care" is paid!
Initial examination
Imagine that you are a good doctor. Entering the room (garage), approach the patient (car), be sure to say hello, say a few kind, calming words to him and offer to undress to the waist (open the hood).
Start with an external inspection of the engine. Remember that nothing reflects internal well-being as much as a pleasant, well-groomed, healthy appearance.
On the contrary, severe general contamination of the engine, as well as the presence of intense local leaks, indicate poor health. If in the evening, when parting with the car, you prudently placed a clean sheet of newspaper under the engine, take it out and inspect it. Oil leaks and other operating fluids will leave traces on the newspaper overnight, by which you can determine the sources of the leaks and determine their intensity. The higher it is, the sooner you need to take measures to eliminate the malfunctions.
The next step is to check and bring the level of all operating fluids to the norm. First of all, we are interested in engine oil and coolant (antifreeze), since their deficiency has the greatest impact on the technical characteristics of the engine.
I would also like to remind you – believe me, I am not joking – that you need to make sure there is fuel in the tank. Experience shows that some inattentive drivers almost torture the starter and battery to death, forgetting that first the young man needs to be fed and watered, and only then – on the shovel and in the oven.
At the same time, check the tension of the drive belts of the engine's auxiliary units (cooling system pump, generator, power steering pump, air conditioning). Make sure the belts are not sagging or torn. If everything is in order, shake off your trousers and get behind the wheel.
Before starting the engine
Don't rush to start the engine right away. There's no point in rushing! First, turn the key to the "ignition" position... As a rule, a number of lights come on on the dashboard of all modern cars. At this stage, we are particularly interested in two.
The first is the emergency oil pressure light, the second is the battery recharging indicator light, which indicates that the generator is ready to start working after starting the engine. Both of them should light bright red when the ignition is on, even before starting the engine. But what if one of them does not light? If the recharging light does not light, it is half the trouble, but if the emergency oil pressure light does not light, it is an alarming "bell". Be careful, you have lost control over the lubrication system! Engine oil pressure is the main indicator of the unit's serviceability. Without monitoring the oil pressure, you risk having to "get" a major overhaul of the engine with all the ensuing consequences.
The cause of the malfunction is either poor contact between the terminal and the sensor, or the sensor itself. The sensor should usually be looked for in the area of the oil filter. The malfunction must be eliminated. Only after you have made sure that everything is in order, start the engine.
"Cold" start
A working engine with well-adjusted fuel and ignition systems and a working battery starts in one attempt within 3-5 seconds. Consistently occurring problems with "cold" starting indicate malfunctions. Let's assume we avoided this and the engine started...
We look at the instrument panel. The two lights mentioned above should go out.
Caution: If the oil pressure light remains on for 5 seconds, 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 causes: low oil level, faulty oil pressure sensor; the oil pump oil receiver mesh is clogged; the oil pump is faulty; severe wear of the main and connecting rod bearings of the crankshaft.
If the oil pressure is OK, we proceed to inspect the engine in warm-up mode.
Warming up the engine
The speed of a cold engine is approximately 1.5 times higher than the rated idle speed, which is usually 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 (as well as idle speed).
If your car is equipped with a tachometer and a dial gauge showing the coolant temperature, this process is easy to monitor.
When warming up occurs according to the above scenario, the idle system and engine cooling system operate normally.
If the engine temperature does not reach the required level, the thermostat valve is most likely to blame. There are many more reasons for engine overheating and they are reflected in the technical reference.
After the engine has warmed up sufficiently and the idle speed has stabilized (you will find out about this from the readings of the control devices), it's time to listen to the engine sing.
A beautiful, sonorous voice means a healthy body
Doctors assure that this statement is completely true in relation to a person. The same can be said about the engine.
A functioning engine makes a steady hum and "ticks" like a clock. Some mechanics say that it "whispers." Despite the figurativeness of the expressions, you probably understand what they mean.
If the engine runs unevenly, with failures, periodically vibrates, know: this indicates its malfunction. Sometimes malfunctions are a consequence of wear of engine parts and a drop in compression in the cylinders, but most often the causes are leaky intake tract, clogged air filter, malfunctions in the ignition system and fuel system. 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 the high-voltage wires from the spark plugs, it is not difficult to find the "saboteur". Once you get to the faulty cylinder, the nature of the engine's operation will not change.
Often the cause of the 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.
It is impossible not to mention extraneous noises and knocks. Let us stipulate right away that such a diagnostic method is "aerobatics" and is not within the power of all professionals.
Car enthusiasts should keep in mind that any sharp metallic sounds indicate a malfunction. If they are "produced" by attachments (generator, pump, power steering) - this is half the trouble. You can determine the "culprit" of the noise by successively removing the drive belts of these units. If after removing the next belt the extraneous noise disappears, shake the corresponding pulley to determine the radial and axial play of the bearings. Most often, they are the ones that disturb the peace.
Much greater troubles are threatened by knocks coming from the belly of the engine itself. They are listened to in various engine operating modes using a car stethoscope or, if there is none, a dry stick of about 10 mm in diameter made of hard wood (it is pressed to the cheekbone below the earlobe). In this way, it is possible to identify defects in the gas distribution mechanism, cylinder-piston group, and crank mechanism.
Let us emphasize once again that in order to make a diagnosis, musical ear is not enough; you need to have professional experience and excellent knowledge of the "matter part".