Starter Motor Troubleshooting

A vehicle owner’s focus may mostly be on the fine working of the engine, the gearbox, the tyres and the presence of sufficient fluids (fuel, water, transmission fluid, brake fluid, etc.). There is however, an important yet mostly taken for granted component – the starter. Owners seldom think about the starter, maybe less about how it works and how to take care of it and the problems it may present to you. In this discussion, we aim at rectifying this by telling you more about the starter motor.

The Starter motor and its working

We can become technical and dismember the starter motor piece-by-piece, explaining the function of each part, but we will not do this here. We will discuss the primary function of the starter motor briefly but we will first look at how Wikipedia defines a starter: A starter is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine’s operation under its own power.

This is the main function of the starter. In the olden days, when vehicles were still in their infancy stage, a crank handle had to be used to turn the motor and start combustion procedures. The starter replaced this arduous task.

Hand Crank Ford
a crank handle had to be used to turn the motor and start combustion procedures

The following image of the main components of a starter, can serve as a tool to assist you during the discussion of how a starter motor works. So how does a starter work?

Starter Layout

The starter is an electric motor that turns the engine over when you turn the ignition beyond the ignition on position. The battery current activates an electromagnet inside the starter that in turn enables the pinion to engage with the gear ring on the flywheel of the engine, and this spins the engine over; simultaneously electricity go to the spark plugs via the spark plug wires, completing the start of the combustion process. As the engine turns, the starter disengages and the electromagnet stops. The pinion rod pull back into the starter in order to prevent the pinion gear to make further contact with the turning flywheel because a turning flywheel will only cause damage to an interacted pinion. This in short is the basic function of a starter motor.

Not all starter motors are the same; there are different types of starter motors.

Starter Motor Types

According to the site “How a car works”, there are two types of starter motors, the inertia type and the pre-engaged type. We will share their explanation of these two types for the sake of informing you, the reader:

Inertia Type

In this type, a bendix gear throws the pinion towards the motor. The pinion moves along the thread of the motor shaft and engages with the flywheel gear ring. It stops at the end of the thread, begins to turn with the shaft and so turns the engine. The inertia of the heavy piston assembly prevents it from spinning immediately when the motor shaft turns, so it slides along the thread and into engagement. When the engine starts, the pinion turns faster than its shaft; the spinning action screws the pinion back down its thread and out of engagement. The pinion returns so violently that there has to be a strong spring on the shaft to cushion its impact. This violent engagement and disengagement can cause heavy wear on the gear teeth, so to overcome this, the pre-engaged starter was born.

Pre-Engaged Type

This type of starter has a solenoid mounted on the motor. The solenoid not only switches on the motor, it also slides the pinion along the shaft to engage it with the gear ring of the flywheel; this is done by way of a sliding fork. The shaft has straight splines rather than a Bendix thread, so that the pinion always turns with it. The solenoid has two sets of contacts that close one after the other. The first contact supplies a low current to the motor so that it turns slowly – just far enough to let the pinion teeth engage. The second contact then closes, feeding the motor a high current to turn the engine. The starter motor is saved from over-speeding when the engine starts by means of a freewheel clutch. The return-spring of the solenoid then withdraws the pinion from engagement.

According to the blogspot Whatisstressuni, there is a third type of starter:

Gear Reduction Type

This type of starter motor contains a magnetic switch, a compact high-speed motor, several reduction gears, a pinion gear, a starter clutch etc. The extra gears reduce the motor speed by a factor of one to three or four and transmit it to the pinion gear. The plunger of the magnetic switch directly pushes the pinion gear, located on the same axis, and this cause it to mesh with the ring gear of the flywheel. This type of starter motor generates much greater torque than the conventional type.

There we have it, the three basic types of starter motors. You should now have a better understanding of the working within the different types of starter motors. The main points to keep in mind, is that we have moving parts and electrical currents in work within these systems. Wherever these are present, there will also be a high likeliness that something may go wrong. This will create issues with these systems. Let us have a look at these.

Starter Motor Issues

Let us be frank, starter failure is inevitable, it is surely just a matter of time; the starter motor will eventually run its course, whether this is because of poor maintenance or just due to every day wear and tear. The two components most commonly prone to fail, are the solenoid or the starter motor itself. When the starter begin to wear out or when it actually fails entirely, then it will display signs that will indicate to you where the problem may be. The most common signs of a failing starter is a no-crank or slow-crank condition. A worn-out component, a bad electrical connection or an insufficient battery usually causes this condition.

Is this the only way to detect starter failure? Surely not, according to Dan Ferrell (2016), the most common way to detect a sign of starter motor failure is through sound, or even the lack thereof. He turns our attention to the following sounds that may indicate starter failure:

Whirring sound:

An excessively worn solenoid will not be able to engage the pinion gear with the flywheel. This will create a whirring sound because the armature in the starter will spin all by itself, unable to crank the engine to a start.

Buzzing sound

Even though the electrical current reaches the solenoid, it fails to activate the solenoid’s plunger successfully, so the pinion gear cannot engage with the flywheel. This is usually due to a poor current flow (a low battery charge / poor electrical connections along the starting circuit / corroded battery terminals).

Loud click

A single, solid click may indicate that the starter circuit is not receiving enough current. The solenoid needs enough voltage to operate and when there is a poor earth connection somewhere, the starter motor will absorb all the current, shutting off the solenoid. You will only hear the loud click. The click may also be indicative of a mechanical problem somewhere in the engine itself.

Grinding noise

If you hear a harsh or grinding noise as you attempt to crank up the engine, then it may be that you have a loose starter motor (check the mounting bolts), or a flywheel or pinion gear with broken or worn-out teeth. If the gears on the flywheel and pinion are not able to mesh properly, all you hear is the sound of metal teeth clashing loudly.

No noise

When you try to start your car, you may hear no sound at all. This silence may be due to electrical issues, such as a failed battery; a failed system component (have the relay or safety switch inspected), or even a corroded electrical connection somewhere that prevents current from reaching the starter.

Fortunately, common starter motor problems tend to happen in predictable places. At the Autozone site, they discuss the following issues that may be helpful if you suspect starter motor failure:

Over Tightening:

It is important to hand-tighten mounting bolts and try to avoid cracking the mounting flange because it is made of cast steel. Remember the cause of the grinding noise!

Broken pinion

A pinion with severely damaged teeth all the way around (improper contact with the flywheel ring gear) is usually caused by a faulty ignition switch or attempting to crank the engine when it is already running. Do also keep in mind the cause of the grinding noise!

Kick Back

The engine kicks back when the pinion is engaged but is misaligned with the flywheel and the starter attempts to crank the engine. This is usually caused by an existing fuel or ignition timing problem.

Poor Grounding

The mounting base ensure that the starter motor is ground properly. In the event of the motor not grounded properly, then you can be in for a starter not working properly.

Loose Electrical Connection

When the electrical connection to the starter motor from the battery is not tight, it can cause arcing and burning.

Melted Terminal

Cranking an engine for more than 10-12 seconds, may cause critical electrical connections to become overheated and this may cause them to melt.

Apart from all the sounds you need to be aware of, and the other issues discussed here that may cause starter failure, two other components (if they fail) need more specific mentioning, because they will also cause starter issues: the starter relay and the solenoid itself.

Starter Relay

The starter relay may also contribute to a starter motor not working properly. According to the autoblog Yourmechanic, the starter relay redirects power from the battery to the starter solenoid. It is the solenoid that then activate the starter to spin over the engine, so whenever the relay fails, the solenoid will not work. Any of the following symptoms may be present when a starter relay fails – Vehicle does not start; Starter stays on after engine started; Erratic starting of the vehicle; Clicking sound coming from the starter.

Starter Solenoid

Even though some issues with regard to the solenoid was said, it will do no harm to say a little bit more. The Autozone site warns us that the following may contribute to a solenoid going bad:


When moisture is inside of a solenoid, corrosion can occur that will interfere with electrical conductivity.


Holding the ignition key in the “start” position for an excessive amount of time pulls a lot of current through the solenoid and can melt contacts and solders.

Over Tightening

Excessive torqueing of fasteners can break posts or other vital components on or inside the solenoid, which can make it malfunction.

Incorrect Wiring

Installing the solenoid incorrectly can cause the solenoid to short out and burn up internal components.

The starter motor and its solenoid is clearly an equally important component as any other component in your vehicle. It needs the same amount of maintenance and care for it to serve you well. A starter and a solenoid is prone to fail during its lifetime, so remember, whenever you experience any of the abovementioned issues, and you do not possess the relevant knowledge to address these issues, then please visit a reputable workshop and have qualified mechanics and technicians fix the issue. We at Steves Auto Clinic welcomes you at any of our branches for starter related issues, so consider visiting a reputable franchise with more than 35 years of experience.

Sources consulted during the writing of this article:
Autozone. Undated. How starters go bad. Online available at: Accessed 25 July 2018.
Autozone. Undated. How starters Solenoids go bad. Online available at: Accessed 25 July 2018.
Ferrell, D. 2016. Bad Starter Symptoms: Why Won’t My Car Start? Online available at: Accessed 25 July 2018.
How a car works. 2018. Blog – How the starting system works. Online available at: Accessed 25 July 2018.
Whatisstressuni. 2012. Starter motor types. Online available at: Accessed 25 July 2018.
Wikipedia. Starter (Engine). Online available at: Accessed 25 July 2018.
Yourmechanic. 2016. Symptoms of a Bad or Failing Starter Relay. Online available at: Accessed 25 July 2018.