Starter Motor repair & replacement made easy

How does a starter motor work?

When early engines were made, starting them was done by cranking a handle attached to the crankshaft. This was obviously very tiring, inconvenient and in some cases quite dangerous too! Therefore a more convenient device was designed, powered by a battery to do the work and the modern starter motor was born!

Think of it as the spark that ignites the whole process. When you turn the key or press the start button in your car, the starter motor jumps into action.

Whilst simplistic in its design, like any electric motor, it does have a number of internal components. Without going into the minute details of how electric motors work, the basic concept is that when an electrical current is passed through coiled wires of the armature it reacts against the magnetic plates on the housing and spins it around.

There are of course a lot of other parts involved, from the contact brushes that carry the electrical current from the source to the rotating shaft of the armature, to bushes, pinions and a solenoid that fires the gears on the shaft into the vehicle flywheel to engage with the engine.

When a start motor fails, it’s generally either the brushes that have worn out, the winding on the armature that has failed or the solenoid that has seized. However, these days, few operations will strip a starter motor to refurbish it as this is both time-consuming and the parts are not always easy to obtain in small numbers. Therefore, exchanging the faulty unit with a new one is cheaper and quicker.

What does a starter motor replacement job involve?

A starter motor replacement job involves several key steps to ensure your car's engine starts reliably. Here’s a simplified overview of the process:

• First, the mechanic raises the car using a lift or jack to gain better access to the underside of the engine.
• The battery is disconnected to prevent any electrical shorts or accidents while working on the starter motor.
• The mechanic then locates the starter motor, which is typically mounted near the bottom of the engine. Any components obstructing access, such as the air intake or exhaust manifold, may need to be removed.
• Next, the wiring connected to the starter motor is carefully disconnected. This usually includes the main power cable and the ignition switch wire.
• The old starter motor is unbolted and removed from its mounting position on the engine.
• Before installing the new starter motor, the mechanic inspects the flywheel or flexplate for any damage, as this is what the starter motor engages to turn the engine. If any damage is found, it will need to be addressed before proceeding.
• The new starter motor is then positioned and bolted into place, ensuring it is aligned properly with the flywheel or flexplate.
• The wiring is reconnected to the new starter motor, making sure all connections are secure and free of corrosion.
• Any components that were removed earlier to access the starter motor are reinstalled.
• The battery is reconnected, and the mechanic tests the new starter motor by starting the car. They check to ensure the engine starts smoothly and that the starter motor engages and disengages correctly.

This job requires skill and precision, which is why it’s best done by a professional mechanic.

How do I know whether I need a starter motor repair or replacement?

A faulty starter motor can sometimes be repaired, if there are bad cable connections, but usually requires a full replacement if it’s “burnt out”. Look out for these key signs and symptoms:
* The most obvious and usual occurrence is that when you turn the key or press the button to start the engine, nothing happens!
* When you do try to start it, knowing the battery is good, you may hear a single click from the starter motor, which is the solenoid firing, but there is no rotation.
* Providing the battery is known to be in good condition, it is the next obvious point of a vehicle failing to turn over.
* Please do note though, if you hear a rapid clicking, that is more likely to be the battery not having enough power to actually turn the motor, but enough to keep firing the solenoid, in which case it's the battery that is faulty or discharged.
* When the battery is known to be in good condition but the engine is very laborious when turning over.

How do I test a starter motor?

Testing a starter motor at home requires some basic tools. It is the electrical system of your car after all so extreme caution is advised.

Disconnect the negative terminal of the battery to prevent any accidental electrical shorts. The starter motor is usually located at the lower part of the engine near the transmission housing. The first thing to do is check the starter motor and its connections for any obvious signs of damage or corrosion.

Then, use a multimeter to check the battery voltage. It should read around 12.6 volts when fully charged. If the battery is low, then it could be the battery that needs replacing.

You can also test the starter solenoid by using a multimeter (reconnecting the negative terminal of the battery) at the terminal when they key is turned to the start position. If there's no voltage, the issue might be with the ignition switch, wiring, or a related component.

We highly recommend considering seeking help from a professional mechanic or book a car won’t start diagnostic.

What does it mean if my car won’t start but is just making a clicking sound?

The starter motor itself could be faulty. If the starter motor isn't functioning correctly, it may not be able to engage the engine properly, resulting in a clicking sound.

On the other hand, it could also be the starter solenoid which is responsible for sending an electrical current to the starter motor. If the solenoid is bad, it can result in a clicking noise as it tries to engage but fails to start the engine.

We have found that the most common cause is a dead or weak battery. If the battery doesn't have enough charge to start the engine, it may only produce a clicking noise. It’s best to get the battery tested and replaced in this situation.

Can a starter motor be replaced by a mobile mechanic?

Yes, a starter motor can be replaced by a mobile mechanic as it is a fairly straightforward job. Mobile mechanics usually carry the necessary tools and equipment for a wide range of repairs, including starter motor replacements.

If your starter motor fails, your vehicle may struggle to or not start at all. This typically means you would need to tow your car to a garage, which can be costly and time-consuming. A mobile mechanic eliminates the need for towing by coming to you. By booking with a mobile mechanic, you can avoid this hassle!

To know more about the cost of starter motor replacement, you can use our starter motor replacement price estimator tool here.