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The Most Common Signs and Causes of Starter Motor Failure

Starter Motors

David Taylor

15th Dec 2017

    The demand for modern starter motors to be powerful, yet smaller for weight and fitment presents a problem. Starter motors are more likely to fail.
    But how do you know that it is actually the starter motor that has failed? What are the most common signs of starter motor failure? And, what can you do when the starter motor does fail?
    As the starter motor is often hidden in the depths of the mechanics, the most common way to detect a sign of starter motor failure is through sound. Below we will list a type of sound and then the possible issue related to your starter motor. We will also list the possible other causes that may not be starter motor related.
    Remember, if you do have a faulty or broken starter motor, we buy old, faulty cores. Find out more details here.


    If your car is making a clicking sound when you turn the ignition, then there could be various issues with your starter motor. If you’re confused with what clicking sound you should be listening for, listen to the sound featured in the video below.
    Poor Wiring Connection
    Your trigger wire, or other wires in the system, may have come loose. If this is the issue, then it should be an easy fix for a mechanic. In the best case scenario, it could just be a simple matter of fiddling with a few connections, but it could also potentially involve rewiring the entire system.
    Poor Earth Connection
    The solenoid needs a certain amount of voltage to operate. If you have a poor earth connection then the solenoid will operate, but the starter motor will absorb all the current flow and shut off the solenoid. Hence the click. This is an easy fix, however we recommend that it should definitely be a fix for a mechanic.
    Defective Solenoid
    Solenoids have a habit of getting overheated. If this is the case, then your starter motor is broken beyond repair. Find a replacement here. It may be worth asking a mechanic to look over your car. Sometimes an overheating starter motor may be caused by overheating issues in your car.
    Defective Starter Motor
    Another overheating issue, this time it may be the electromagnet inside of the starter motor that is broken. Again, this issue is beyond repair and you will now need to replace the complete starter motor. Ask your mechanic to check over the inner workings of your engine. This may, again, be due to the overheating of other mechanics within your car.
    Defective Ignition Switch
    Starter motor failure and ignition switch failure present quite similar symptoms. One key check, that can tell you the difference between the two, is to see if the oil, brake and charge light function is present at position two. If the lights fail to turn on this could be a sign of electrical issues in the ignition switch.

    Whirring Noise

    If your car is making a whirring sound when you turn the ignition then you may have significant issues with your starter motor. The best way to describe the sound is to imagine a blender quietly whirring away. The sound may only last for a second or it may continue for longer.
    The reason for this whirring sound is due to the pinion gear not engaging with the flywheel. This is almost always a sign of a faulty solenoid and you will need to buy a complete starter motor replacement.

    Grinding Sound

    If your car is making a grinding noise when you turn on the ignition, then there could be various issues with your starter motor or flywheel. If you’re confused with what grinding sound you should be listening for, then have a listen to the sound featured in the video below.
    Worn Teeth on the Pinion Gear
    If you have worn or missing teeth on the pinion gear, then the grinding noise may be a consequence of the pinion and flywheel grinding against each other. You will need to replace the starter motor before further damage is done to the flywheel.
    Worn Teeth on the Flywheel
    Similar to the above, if you have worn or missing teeth on the flywheel then the grinding noise may be a consequence of the two parts grinding against each other. You will need to replace the flywheel in this scenario.
    Loose Mountings
    Another issue that often causes a grinding noise is loose mountings on your starter motor. General wear and tear on the bolts supporting the starter motor is responsible, and it is best to get the issue fixed before it causes significant damage to the starter motor or flywheel.


    Another sound to listen out for is a general buzzing noise. The sound is quite similar to that of an electrical fence. This is a sign that not enough electricity is getting to the starter motor. This is due to various issues including: a weak battery, poor wiring, and dirty or corroded battery terminals. Make sure you have a qualified mechanic investigate the cause of this issue.
    Turns Slowly
    If the starter motor is turning slowly then there could be several issues at play. The first thing to check is that the battery has enough charge. This is often the cause as a weak or defective battery will not be able to supply the solenoid with enough electricity. It could also be:
    Trigger Wiring
    Ignition switch and starter motor failure present similar symptoms. On this occasion, if your car is turning slowly, this is probably due to faulty wiring. This is caused by the faulty wiring failing to supply the solenoid with the appropriate electricity.
    Generally Worn Starter Motor
    If your starter motor is starting to get generally worn down, then the car may start to turn over a little slower. Unfortunately, this may signal that the starter motor is on its way out and will need to be replaced.
    Corroded Battery Cables
    Another issue that may slow down the turn over is corroded battery cables. This simply restricts the amount of current from reaching the solenoid and it may take longer to get a quality electrical source to the starter motor.
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