Do you have a bad starter motor, and you want to know if it is possible to fix a starter without replacing it? You’ve come to the right place, for we have researched this question, and we have the answer for you.
A modern starter has a few components, and some are not serviceable. So, it would depend on which part of the starter went bad to determine whether you can fix it or should rebuild it. You can fix the following components:
- wire contacts
- starter solenoid contacts
- ignition cylinder
- starter motor brushes
Let’s take a closer look at the different components of a starter motor in the succeeding sections. Having a deeper understanding of how a starter motor works and its components will help you determine if you can still fix or rebuild the car's starter motor.
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How does a starter motor work?
When you start your car, you will hear a cranking sound just before the engine starts. This sound comes from the starter motor. When you turn the key in your car, it doesn’t actually start the engine. What it does is send power to the starter motor to start the engine.
Internal combustion engines are feedback systems. What this means is that the inertia or the remaining energy from the previous cycle will initiate the next cycle. Thus, once the engine starts running, it will perpetually run until it runs out of fuel or electrical energy.
However, the catch of feedback systems is that there should be a separate system that will initiate the engine’s cycles. This is where the starter motor comes in. It is responsible for initiating the engine’s cycles. Then it will shut down once the engine is already running.
Starter Motor Components
When you turn the key in the ignition or when you press the ignition button, a small amount of electrical energy from the battery goes to the starter solenoid.
The starter solenoid has an electromagnet that only needs a small amount of electrical energy to magnetize. This electromagnet surrounds a moving core that acts as a plunger.
Once the starter solenoid activates, the electromagnet forces the core to slide to one side. This movement does two things.
First, the core pushes the pinion gear out of the starter motor while slightly rotating it. This rotation is because of the helical spline of the pinion gear. The rotation makes it easy for the pinion gear to mesh with the engine flywheel. The flywheel is a large gear that makes it more effective at cranking the engine.
Older models of starter motors have a removable starter solenoid. These older solenoids do not have the function of moving the pinion gear forward to mesh with the flywheel.
The second result of the core movement is a conductive plate completing the circuit to provide electrical energy to the starter motor. This powers the starter motor at the same time that the pinion gear meshes with the flywheel.
Gear System Of The Starter Motor
The pinion gear is smaller than the flywheel gear by a ratio between 15:1 up to 20:1.
This gear ratio increases the torque available to the pinion gear to crank the engine. However, the torque from the pinion gear will not be enough if it will only depend on the gear ratio.
To make sure that the pinion gear has enough torque, the starter motor has a planetary gear set inside.
A planetary gear set has a sun gear in the middle. Three planet gears connect around the sun gear at regular distances, and a ring gear that surrounds the three planet gears. A carrier connects to the center of the three planetary gears.
The motor of the starter spins the sun gear. The movement of the sun gear spins the three planetary gears. The movement of the three planetary gears rotates the carrier with more torque. The rotation of the carrier rotates the pinion gear and provides it with the torque that it needs to crank the flywheel.
With the core in the proper place, the starter motor will rotate the pinion gear with enough torque to start the engine.
Releasing The Ignition Switch
Releasing the ignition switch disconnects the circuit that supplies power to the starter solenoid. The loss of power demagnetizes the solenoid, and the spring will push the plunger core back to its original position.
Moving to its original position disengages the pinion gear from the flywheel. This movement is important because the flywheel will begin to spin at a much faster speed once the engine starts to run on its own. Disengaging the pinion gear prevents the greater speed of the flywheel from damaging the starter motor.
The second result of the plunger core’s movement back to its original position is to disconnect the circuit that supplies power to the starter motor. Without electrical energy, the starter motor will stop rotating.
If you don’t turn off the ignition switch after the engine runs on its own, the speed of the flywheel will damage the starter motor.
Modern starter motors have a one-way clutch. The one-way clutch automatically engages the pinion gear when it meshes with the flywheel. However, when the flywheel rotates at a higher speed, the one-way clutch will disengage the pinion gear. This disconnects the pinion gear from the starter motor.
This allows the pinion gear to rotate with the flywheel, but its movement will no longer affect the starter motor. This effectively prevents damage to the starter motor if you fail to release the ignition as soon as the engine runs on its own.
How to fix a starter motor without replacing it?
There are parts of the starter motor that you can check and fix that can bring your starter back to life. However, the majority of the parts of your starter are not serviceable and require replacement once they start to fail.
The first thing that you need to check is the wires that go to the starter solenoid. These wires are constantly exposed to the weather, and this can easily corrode the contacts after months or years of exposure.
Corrosion can reduce the conductivity of the contacts, and this can cause a problem with the starter motor, making it seem like you have a failing starter motor.
Use 200 to 250 grit sandpaper to remove the corrosion from the contacts of the wires that go to the starter solenoid. Damage to the wires will also prevent the starter solenoid from getting enough electrical energy to magnetize and start the starter.
220 grit sandpaper is available on Amazon through this link.
Starter Solenoid Contacts
Remember the two contacts that the conductor plate bridges to complete the circuit to supply power to the starter motor? Corrosion can damage these contacts and wear them out. The corrosion will ruin the conductivity of the contacts, but this is not the biggest problem.
If the contacts are loose or too worn, the movement of the conductive plate might no longer reach the contacts. Without the conductive plate, the contacts will not have a complete circuit to supply power to the starter motor.
There is a repair kit for starter motors to replace these contacts.
Some newer starter motor models—especially those made by Honda—do not have an external starter solenoid that you can access easily. These models have their solenoid inside the starter, close to the pinion gear.
Additionally, some starter motor models have a starter solenoid that can be challenging to open and repair. Be careful in opening these solenoids because breaking the locks will prevent you from putting them back together.
In contrast, older models of starters have a removable solenoid for easy replacement because solenoids break down twice as much as the starter motor itself.
A Starter Contact Kit is available on Amazon through this link.
The ignition cylinder might not be a direct part of the starter motor, but a failing ignition cylinder will prevent electrical energy from reaching the starter solenoid. Without the power to the starter solenoid, the starter motor will behave as if it is dead and needs replacement.
Get the part number for your ignition cylinder and get an exact replacement. Replace the ignition cylinder once you get the replacement part.
Dorman 924-724 Ignition Lock Cylinder is available on Amazon through this link.
Starter Motor Brushes
The starter motor brushes or carbon brushes themselves can wear out, and this can cause the starter motor to stop working. The carbon brushes in motors are what conduct electricity and supply the motor with the power that it needs to work.
If the carbon brushes are worn out, there will be a reduction in the flow of electricity to the point where there will no longer be any electricity flowing into the motor at all.
There are replacement starter brush assemblies that you can buy to replace the worn-out brushes in your starter motor.
Moreover, some starter motor models have springs that push the brushes into place. The spring of the starter brushes can break or fall off. Replacing the brush assembly should also replace the springs.
Starter brush holder assembly is available on Amazon through this link.
There are parts of the starter motor that you can fix and replace to get your starter motor usable once more. Troubleshooting can help determine the issue. Then, you can either repair these components yourself or hire a reputable engine technician for the job.
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