One of the disadvantages of a car engine is the impossibility of starting without an external auxiliary system. To obtain the minimum starting speed, it is necessary to use an auxiliary electric motor to drive the car engine. This motor is called a starter or electromotor.
The complete start-up system of an engine is composed of DC electric motor powered by the battery pack, gear, electronic control module, and wiring. The use of the term electric motor is because the starter is a DC motor.
The power consumed by starters for starting the heat engine depends primarily on the outside temperature. The lower the temperature, the higher the starting speed and torque.
The viscosity of the lubricating oil and the low temperature of the intake air make cold starting more difficult. For this reason, during cold weather periods, without a battery in good condition, starting is difficult or even impossible.
A starter is mainly composed of a DC motor and a coupling system. To start the engine, the car starter is coupled to the gear wheel positioned on the flywheel using a sprocket. The gearing between the starter sprocket and the flywheel crown is not permanent but only occurs at start-up.
The mode of operation is relatively simple. When the electric start-up circuit is closed, the solenoid (8) actuates the coupling lever (7) which pushes the gear sprocket (5) outwards to engage the gear wheel of the engine flywheel. At the same time, the supply circuit of the electric motor is closed, which allows it to start.
The starter is of direct current and is composed of a stator (3) and a rotor with a collector (2) with brushes (1). The stator is of two types: with winding or with permanent magnets.
When the solenoid (8) shuts off the power supply circuit of the starter, through the electrical connectors (9) it is supplied from the battery pack both the stator winding and the rotor because they are connected in series.
To compensate for the decrease in torque generated, starters with permanent magnets are provided with a mechanism. This mechanism reduces the speed and amplifies the torque available at the starter coupling pinion.
The transmission ratio between the starter sprocket and the flywheel crown is between 1:10 and 1:20. When starting the engine, to reach its minimum starting speed of 100 rpm, the starter rotor has the speed of 1500 rpm, at a transmission ratio of 1:10.
When the engine has started it has a speed of around 1000 rpm. The transmission of the movement is done inversely, from the engine to the sprocket of the starter. Without a protective mechanism, because the transmission ratio becomes 10: 1, the rotor would drive at 10,000 rpm, which would result in its destruction.
The one-way coupling allows the pinion to be disconnected from the starter rotor when the speed of the motor becomes higher than that of the rotor. This coupling operates in the following way: the housing is connected to the starter rotor, the casing rotation involves the rollers that compress the coil springs, the rollers move in the same direction as the casing and press on the shaft, driving it.
As the sprocket speed becomes higher (the car motor has started) the rollers move in the opposite direction by disengaging the casing sprocket, thus implicitly by the starter rotor.
The electric current consumed by the starters is approximately 150 A with a peak of 500 A at the initial moment of the start-up phase. When operating the starter, the battery voltage decreases due to high power consumption. If the battery pack is in good condition the voltage drop should be around 0.5 V.
The starter should not be operated for a long time. Usually, if the battery is low, the startup is cumbersome and the starter operated for a long time. This procedure is not beneficial because it results in premature wear of the gear pinion and brushes in contact with the manifold.
For optimum operation of the starter system, the battery must be charged and the contacts between the starter and battery connectors (due to the high current consumed) must be clean, free of impurities and on all available surface.
Car starter problems and bad symptoms
A bad start can generate some different symptoms and problems. It can rotate the engine, but without lifting it or turning it too slowly. It can generate abnormal noises that require verification. Or it may not rotate at all, possibly accompanied by a noisy or silent magnetic switch.
The scenarios below can help you diagnose the starter motor circuit problem, evaluate the causes, and act properly. Always refer to the manufacturer’s manual, however, for specific startup diagnostics and safety information for that vehicle.
Starting the car is delayed or difficult
Especially when the engine is hot. Even if you repeatedly turn the ignition on, you will notice that the car refuses to start. However, before “blaming” the starter, you should make sure that the battery is charged and that it transmits enough electricity.
The starter motor is designed to rotate at a certain number of RPMs. If the battery connections or cables are corroded or dirty, this will result in a slower start of the starter motor than the specified RPM. Make sure all battery connections and cables are clean and properly secured.
Other causes may be the pinion that does not engage with the toothed crown. Alternatively, the clutch may slide or the engine may be blocked.
When you try to start the engine, you hear a beating sound
- Beating sounds may be associated with physical damage to the flywheel/plate. Fully check the flywheel/plate for cracks, indents, protrusions, etc.
- A malfunctioning electromagnetic valve at the starter motor or a defective starter motor can generate clapping noises. Refer to the vehicle manufacturer’s recommended procedures and safety precautions for checking the electromagnetic valve and starting motor.
- The battery must be fully charged (12.6 volts) according to the manufacturer’s recommendations, and the cables and terminals of the battery clean and in good condition.
- Other causes for abnormal starter noise may be caused by a worn brush, worn sprocket, or poor slip or pinion coupling.
When rotating the key in the ignition, no specific noise is heard
Normally, when you want to start the car engine and operate the ignition, you should hear a natural sound. If it does not appear, the hub may be defective, but the starter will likely be damaged.
If your vehicle releases smoke, then the starter may be short-circuited. The reason why smoke is coming out is that the electricity from the power supply is trying to pass through the short-circuited starter. This will result in the appearance of a gray or black smoke mist from the car engine.
If there is no engine turning and you hear a noise coming from the starter, this is a phenomenon known as freewheeling. This indicates that the flywheel cannot come into contact with the starting gear, so you must replace the car starter.
Smell of burnt
If a sense a smell of burnt inside and outside the car, it is an indication that the car starter is faulty. Most of the time, with the odor the smoke will appear, but even if the smoke does not appear but you only feel a smell of burning, you should check the starter motor immediately.
What causes the starter to fail?
Regarding the type of car components, the starters are part of that category that has a very long service life, it is not a consumable part, which needs to be replaced after a certain period or after a limit of miles traveled.
In principle, a starter can operate in perfect condition even for a few good years, requiring minimal care and attention. However, there are certain actions that drivers frequently commit erroneously, certain inappropriate behaviors or “unhealthy” habits that affect the existence of the electric motor and shorten its service life.
Here are the causes that can lead to wear and/or failure of a car starter:
Power Problems – When the power supply and transmission occur with oscillations, and this happens frequently (either too high a load of electricity is transmitted to the electric motor or too low), the starter may go through various states, from overheating and overloading, until it is under voltage. In this way, because of this discrepancy, the lifetime of a starter can be considerably reduced. It is essential to check at a certain interval the voltage at the battery terminals and, if you notice difficulties in starting the engine, for these reasons, try to solve the problem until it is not too late.
Excessive humidity – Condensation resulting from too long an interval from stopping the engine to restarting the engine can be quite harmful to the electric motor. When the engine is hot, the water is evaporated, but when it is cold, the existing humidity can be a decisive factor for the deterioration of the engine insulation and its corrosion. Ideally, any driver should not allow too long a time from stopping the engine until restarting it, obviously as far as possible, to prevent the appearance of condensation.
Dust accumulation – Dust can be a powerful enough enemy for the starter, but also other components of a car. Even if the particles are small enough, accumulating over time, it can lead to deterioration of the starter, by blocking the elements, which leads to overheating, so to the malfunctioning of this component.
Insufficient lubrication – If a system is not properly lubricated, over time, it may fail due to excessive friction between the parts. On the other hand, too much lubrication is not recommended, as this can lead to overheating of the system.
Excessive heat – When the starter is constantly overheating, it may cause the protective system to melt, which surrounds the coil. If the coil is no longer protected, a short circuit may occur that is likely to damage the entire starter system. For this reason, you should make sure that this key component of any car is well ventilated, so that overheating is avoided.
How much does a car starter cost?
The cost of replacing the starter depends on several factors, the model and brand of the car as well as the store where the electric motor is purchased. On average you can expect an amount between $ 340 and $ 550, all with labor.
The labor is not very expensive since we are talking about a vital part of the engine, without a functional starter, the car cannot be driven. Therefore, immediately replace the electric motor as soon as you recognize one of the symptoms presented above.