Today, a car with an internal combustion engine can be started conveniently from the driver’s seat. All it takes is a simple turn of the ignition key. This is made possible by the starter motor. If the starter is defective, the engine can no longer be started in the normal way. But what exactly is a starter? And where is the starter in the car? Our guide will answer all your questions about the starter motor.

This is the function of the starter motor in the car

The starter motor generates the necessary torque to start the combustion engine. In principle, the starter motor is a small electric motor. This is designed for high and short-term power and sets the engine in motion. The starter draws the necessary current for this starting support from the battery.

To prevent the starter motor from constantly running with the engine, it is decoupled from the engine when its assistance is not needed. For this purpose, a magnetic switch is installed on the starter, which engages the pinion of the starter in the ring gear of the flywheel only when required. A starter freewheel additionally prevents the starter from spinning.

Typical causes for a defective starter motor

If the starter motor is defective, there are various possible causes for the damage. In an older vehicle with higher mileage, wear and tear may be the cause of the failure. Although the starter motor is not a classic wearing part, the component is stressed and worn with every starting process. If the car is often driven on short trips and started frequently, the problem can also occur early on.

• Wear and tear on the starter motor of an older vehicle
• Damage due to thermal overload
• Pollution and moisture penetration
• Material fatigue of the components in the starter motor
• Problem with the power supply

Incorrect use or soiling of the starter

The starter motor in the car can also be damaged by incorrect use and is then broken. This small electric motor is in no way designed for continuous operation. If the starter is operated for too long at a stretch, it overheats, which can be the cause of a defect. If the car’s engine does not want to start, the starter should not be left on permanently. It is better to take a short break between starting attempts.

Dirt and moisture penetration at the starter are also among the frequent causes of a defect at this component. Depending on the vehicle, the starter is mounted quite unprotected in the engine compartment on the engine. In this case, splash water or road salt mist can significantly affect the starter and lead to a defect. Dirt in this area can also become a problem. With an older starter, material fatigue can also be a possible cause.

Common symptoms of starter motor defect

If the starter motor is defective, various signs can point to the problem. Often, however, a defective starter can be recognised in a flash. In most cases, the car can no longer be started despite a full battery. Either the starter motor turns weakly and cannot start the engine, or the component fails completely.

• Starter motor turns only weakly
• Engine will not start
• Starter motor makes noise
• Magnetic switch only clicks
• Starter goes crazy

Clacking or spinning of the starter motor

Other symptoms of a faulty starter motor may be a clacking or clunking sound without the engine starting. Sometimes an unusual noise such as squealing is also heard. Often, a defective starter motor can no longer turn while the solenoid switch is still working. The magnetic switch presses the pinion against the gear rim and the starter motor only clacks.

Other signs can also indicate a defective starter motor. These include the starter motor audibly spinning without the car starting. This in turn may be due to the starter not being engaged or the pinion being worn. Other problems, such as a persistent clacking noise, can be caused by a faulty power supply or ground connection.

Repair or replacement of the starter motor

A defective starter motor restricts the function of the car, which is why the defective part should be replaced. Before the starter motor is replaced, the complete starting system should be checked in the workshop. It is not always clear whether the battery or starter motor is defective. The ignition lock, the starter relay or a fault in the power supply are also possible causes.

Search for faults on the starter or the battery

If there are signs of a problem with the starter motor, the component itself does not always have to be defective. Sometimes the causes lie in the area of the power supply. An empty battery, a poor earth connection or corroded connections mean that the starter motor cannot turn the engine powerfully enough. Battery voltage and voltage at the starter motor should therefore be checked with a multimeter.

A stuck starter can sometimes be activated in the workshop by lightly hitting it with a hammer. If the trick with the hammer does not work, the starter is usually broken. Repairing the starter is usually not worthwhile, as the disassembly and troubleshooting of components takes a lot of time. It is often more practical and cheaper to replace defective starters with good used spare parts.

Changing the starter on the car

Skilled car mechanics with a well-equipped workshop can quickly replace the car’s starter motor. To be on the safe side, disconnect the starter battery before replacing the starter. Then disconnect the connections from the starter housing and mark them if necessary. Then, after loosening a few screws, the component can usually be easily removed from the engine.

After removing the defective starter, check the pinion and the teeth on the flywheel ring gear. The connections and lines should also be checked for damage. The new starter motor can then be briefly compared with the defective part and then installed. The installation of the starter motor and the connection of the lines are done in reverse order.

Buy used starter motor for car

If the starter motor is defective, it is often a good idea to replace it with a good used spare part. Used starters are available for most models and are in good condition. If you want to buy a used starter, you should compare the data and illustrations of the spare part with the existing component. For example, a vehicle with a start-stop system may have a special starter installed.

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