How to check the generator on the car without removing it?
An important node of the electrical circuit of the car is the generator. Its main purpose is to convert the energy received from the rotation of the car's crankshaft into electricity to recharge the battery and power all automotive electrical equipment. That is, in the process of moving the vehicle, this unit generates electricity.
Nothing lasts forever under the moon, and even more so the elements of a car engine. No matter how cool your car is, it constantly needs maintenance. If the generator fails, the engine may simply stall while driving. Accordingly, when the first malfunctions in electrical equipment appear, the causes of the breakdown should be found and eliminated.
Unfortunately, in most cars, removing the generator for diagnostics is quite difficult, so drivers have a natural question: are there any real ways to check the generator without removing it? Answer: There are ways. Let's consider this issue in more detail.
Methods of diagnosis
The easiest way is to get into the car, start the engine and pay attention to the battery charging light. Ideally, it should turn off. If it is on, then there is a problem. Earlier on Vodi.su, we already talked about why the battery light is on for a long time when the engine is running. There may be several reasons:
- stretching the timing belt, through which rotation is transmitted from the crankshaft to the generator pulley;
- weak contact at the output terminals of the generator or battery;
- problems with the generator itself - the graphite brushes were worn out, the rotor bearing jammed, the rotor shaft bushings flew;
- malfunctions of the diode bridge and voltage regulator.
The exact cause of the breakdown can only be determined using a voltmeter or any tester. Ideally, if you measure the voltage at the battery terminals, it should be 13,7-14,3 V. If it is lower, this indicates a discharge of the battery or a malfunction of the generator. With the engine not running, the voltage at the battery terminals should be approximately 12 volts.
If the breakdown is really related to the generator, then the battery will be discharged very quickly, since it does not receive enough voltage while driving. This is fraught with rapid sulfation of the plates and constant undercharging.
It is also recommended that with the engine turned on and the tester connected to the battery, alternately turn on and off all current consumers - headlights, radio, diode backlight, and so on. At the same time, voltage jumps to the smaller side are allowed, but not too large - 0,2-0,5 Volts. If the indicator on the voltmeter display drops sharply, this may be evidence of power leaks, a winding short circuit, or a breakdown of the diode bridge.
Another way to check is to disconnect the negative battery terminal when the engine is running. Wear rubber gloves for this test, and you can also lay down a rubber mat to avoid being electrocuted. If the generator is working, then even with the terminal removed, the engine should continue to work, that is, the electricity for the candles normally comes from the generator.
It is worth noting that this method is considered extreme, since such experiments can actually lead not only to injuries, but also to breakdowns. In addition, on modern cars equipped with an ECU and various electronic fillings, it is forbidden to disconnect the battery from the network, as all settings may be reset.
Signs of a broken generator
So, if the charging light is on after starting the power unit, this is already a reason to worry. The battery charge, according to manufacturers, should be enough for 200 km of travel, that is, it is quite enough to get to the service station.
If the problem is related to the bearing or bushings, then you can hear a characteristic whistle from under the hood. This means that action must be taken as quickly as possible. The alternator belt also has a limited resource. Fortunately, its tension on domestic cars can be checked manually. If you have a foreign car, then it is advisable to perform this task at a service station or in a well-equipped garage.
Problems with the electrical components of the circuit give themselves out as follows:
- the battery charging light is dim;
- the headlights glow dimly, when speeding up, their light becomes brighter, and then dims again - this indicates the unstable operation of the voltage regulator and the diode bridge;
- characteristic motor whine.
If you notice these symptoms, then you need to go for diagnostics to specialists. They will definitely have sophisticated equipment, such as an oscilloscope, to check the generator and take all the readings of its operation. This process is quite complicated, since you have to measure the voltage several times in various operating modes, as well as connect the terminals to the generator itself in order to find out what voltage it produces.
Generator Maintenance
It is quite possible to extend the service life of this unit without resorting to its dismantling and repair. First of all, you need to regularly check the timing belt tension. If it's easy to get to, just put some pressure on the belt, it shouldn't flex more than five millimeters. You can tension the belt by unscrewing the generator mount and moving it in relation to the engine. On more modern models there is a special tension roller. If the belt is frayed, it needs to be changed.
Secondly, the fastening bolts must be tightly tightened to avoid vibrations. Thirdly, it is also possible to check and replace the brush mechanism without dismantling. Remove the negative terminal of the battery, unscrew the back cover of the generator, remove the voltage regulator. If the brushes protrude less than 5 mm, they must be replaced.
It is worth noting that there are repair kits with brushes, holders and rings on sale. Although, the editors of Vodi.su recommend that this replacement be performed only if you have the appropriate knowledge, since in the course of replacing the brushes it is also necessary to wipe the brush holder socket, unsolder and solder the wires back, check the strength of the contact springs, etc.
The brushes take some time to lap, so the battery charging light may not come on. But this is a temporary phenomenon. Also check the alternator pulley, it should rotate freely without play and extraneous sounds.
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