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.
Top Mechanics For Starter Motor Repair & Replacements
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Frequently asked questions about starter motor repair & replacements
Read our answers to questions about starter motor repair costs, symptoms and more.
What is a starter motor?
A starter motor is a heavy duty electric motor that has enough torque to turn the engine in order for it to start, it is powered by the car's battery. 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.
What does a starter motor replacement involve?
Depending on the vehicle and the circumstances, the mechanic will carry out some or all the following
- Mechanic will inspect the starter motor terminals and electrics of the ignition system.
- Mechanic will subject the starter motor to voltage test.
- If necessary, the mechanic will replace the starter motor.
- Mechanic will advise if any other parts need to be replaced.
- Mechanic will start the engine to establish whether the starter motor works correctly.
Can I replace a starter motor myself?
Unless you are a qualified mechanic with the required skills, training and equipment to do the job, we strongly recommend a starter motor replacement is only carried out by a professional mechanic. ClickMechanic can help get you a vetted and local mechanic to carry out the work. Just enter your postcode and your car's registration number at the top of this page and select the work needed to get an instant fixed price up front.
What are the symptoms of a bad starter on a car?
- 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 in 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 long does it take to replace a starter?
On average a starter motor replacement will usually take around 1 hours, but can take anywhere from under 1 to 2.5 hours. The time that the job takes will depend on a range of factors. For example, your vehicle's make and model, year, as well as other factors. Select your car at the top of this page for information on job time and cost for your vehicle through ClickMechanic.
How often should starter motor need to be replaced?
It is likely a vehicle will need a new starter motor at least once in its lifetime. Of course if it fails it needs replacing, otherwise you will be push starting the vehicle each time you want to use it.
If you notice that the engine is struggling to turn over though and you know the battery is in good condition and charge, then sooner rather than later is better to replace the tired old starter motor before it leaves you stranded.
How do you know if your starter motor is broken?
There are a number of symptoms that will tell you whether the starter motor is broken. The most obvious one being when you turn the key or press the button to start the engine and nothing happens.
Can I still drive with a faulty starter motor?
If you suspect there is any issue with your starter motor or if there are concerns about its age or condition, book an inspection with a professional mechanic immediate effect. The starter motor may still start the car but if its malfunctioning or only intermittently works there is of course a real risk it will leave you stranded on a journey at some point. It's best to get it checked and let a mechanic verify the problem as soon as possible.
Is a bad starter motor an MOT failure?
The starter motor in itself would not mean an MOT failure. However, an MOT tester will need to run the engine for an emissions test so if the vehicle cannot be started this may in turn lead to an MOT failure.
What is the average cost to replace a starter?
The average cost to replace a starter is around £225. The exact price will depend on your vehicle and the type of starter fitted. An exact price for your vehicle can be found by entering your postcode and car registration number at the top of the page, and selecting the starter motor repair.
Can starter motors be repaired?
Yes, starter motors can be repaired or rebuild, but it is often more cost-effective and quicker to fit a new unit if the old one is broken. Of course, if a new alternative is no longer available the only option will be to get a specialist repair the broken starter motor unit.
How do you start a car with a bad starter motor?
The method to use to start a car with a bad starter motor will depend on the starter motor's issue. Often the starting issue will be due to a bad or weak battery. In those cases jump starting can help temporarily to get adequate current to the starter motor to help start the vehicle. Push starting could be another option if you have a manual. If the starting issue is due to the starter itself, it will be more tricky to get the car started. In those instances, or if you don't know what the issue is, it is advisable to get help from a professional mechanic to track down the issue and help you start the car.
Where is the starter motor located in my car?
The starter motor is located in the engine bay of the car, and usually mounted to the engine block, near the flywheel.
Can you jump start a car with a bad starter?
Jump starting a car with a bad starter will likely not work even if the battery has enough charge. This is because the starter motor's function is to crank the car's engine to start its combustion cycle.
How much does it cost to replace a starter motor?
Cost for a starter motor repair is on average £225, with prices ranging from £160 to £325. Ultimately, the cost depends on your car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having your starter motor replaced by ClickMechanic by selecting your car at the top of this page
Check out the ClickMechanic price for a starter motor repair. See the averages for different makes below. We consolidate industry standard data with millions of data points to give you the most accurate price. These estimates may include Starter motor - pre-engaged.
Name | Average Cost | |
---|---|---|
Audi | £396 | Get exact price |
BMW | £339 | Get exact price |
Citroen | £247 | Get exact price |
Ford | £240 | Get exact price |
Land Rover | £326 | Get exact price |
Mercedes-Benz | £354 | Get exact price |
Nissan | £247 | Get exact price |
Peugeot | £261 | Get exact price |
Renault | £305 | Get exact price |
Toyota | £267 | Get exact price |
Vauxhall | £288 | Get exact price |
Volkswagen | £278 | Get exact price |
Estimates on average repair costs, such as the above results for a starter motor repair, are based on ClickMechanic's quote data which combines multiple third-party sources. Actual costs may vary. We provide estimates on average repair costs for information only and accept no liability for any inaccuracies or errors. If you think an estimate is incorrect, please contact us to let us know.
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Mechanics that undertake starter motor work
- D Auto Repairs, Manchester
- Dave-Tech, Rochford
- Farmers Auto Repairs Ltd, Sedgley
- Fevtowbars, Pontefract
- Fosters Auto Repairs, Horely
- H&R Motors, Merseyside
- Lexden Vehicle Services, Colchester
- MVMS Mobile Vehicle Maintenance Services, Oxon
- Nda Solutions, Birmingham
- The Tyreman, Steyning
- West Commercial Services, Bedworth