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Signs Of A Bad Starter

Most drivers give little thought to their ignition system until it ceases to function as it should. It is easy to assume that your vehicle will fire up with the turn of a key as expected, but what happens when it does not? Depending upon the situation that you find yourself in, a costly tow might become a necessity, and the need for further diagnosis becomes imminent.

While not all starting concerns are caused by a faulty starter, the prominence of such failures is prevalent enough that this warrants further thought. By knowing the signs of a bad starter, you can recognize the onset of an issue, and make repairs in a timely manner as needed, possibly avoiding becoming stranded in the process.

How Does A Starter Work?

A starter functions by turning an engine until it has enough power to operate.
A starter works by turning an engine over and over.

A starter works by turning an engine over for the amount of time necessary for it to operate under its own power. This process begins when the voltage is supplied to the starter solenoid via the ignition switch. When this occurs, the starter solenoid engages and the starter pinion is moved outward on the starter driveshaft. When this happens, the teeth of the starter pinion gear mesh with those of the flywheel.

Simultaneously, the solenoid also closes high current contacts for the starter, allowing the starter driveshaft to facilitate the rotational movement of the starter’s pinion gear, therefore spinning the flywheel and cranking over a vehicle’s engine. When the power is cut to the starter solenoid with the release of the vehicle’s key, pinion rotation ceases, and a return spring forces the pinion gear away from the flywheel.

Signs Of A Bad Starter

In the case of a starter, complete failure is not always immediate. At times, a starter can present symptoms that are clues as to the status of its health. If any signs of trouble become evident, proper repairs must be made. The following are potential signs of a failing starter.

1. Dimming Lights

When a starter’s wiring begins to reach a high level of fatigue, or a bearing within the starter begins to drag causing resistance, excessive amperage is often drawn. When this takes place, current to other vehicle components suffers. This commonly leads to the dimming of vehicle lighting. Instrument cluster lighting, dome lights, and headlights are all commonly affected by the excessive draw of amperage.

2. Grinding Noise While Cranking

If an intense grinding noise is heard when attempting to start your vehicle, a number of possible issues with your starter are likely to be responsible. The noise that is heard is caused by inadequate engagement of the teeth of the starter’s pinion gear to your vehicle’s flywheel. This is an immediate cause for concern, as a non-resolution of this issue will lead to eventual flywheel damage, requiring replacement. Worn, damaged, or missing pinion gear teeth, as well as loose starter mounting hardware tend to be the leading causes of this symptom. 

3. Grinding Once Started

If you release your vehicle’s key upon hearing your engine roar to life, only to hear a strange grinding noise over the engine’s familiar idle, your starter’s solenoid is likely to blame. This grinding noise is caused by the teeth of your starter’s pinion gear dragging along those of the flywheel. 

When this occurs, the most common failure is within the internal circuitry of your starter solenoid. The electrical contacts contained within are prone to sticking when faulty. This causes the circuit to remain closed, and the pinion gear engaged, even in the absence of supplied voltage. If the solenoid contacts do not open, remove the positive battery cable to disengage the starter. Before replacing the starter, conduct further diagnostics to rule out a faulty ignition switch.

4. Whining Without Turning Over Engine

If you turn your key, only to hear a whining noise in place of the expected firing of your engine, it is time to take further stock of your starter’s condition. What you are hearing is your starter’s drive shaft spinning freely in absence of proper pinion gear to flywheel engagement. The most common culprit is the starter’s solenoid. When this occurs, the solenoid cannot properly facilitate the forward movement of the pinion gear, even when adequate voltage is supplied.

5. Slow Cranking

One of the most common symptoms of a failing starter comes in the form of a slow-crank condition. However, when this symptom is encountered, the first course of action is to verify the health of your battery cables to ensure the proper delivery of voltage to the starter. This can be done with the assistance of a digital multimeter. Battery voltage should be present at the main positive lug on the starter. If the voltage at this point is less than that present at the battery, or if your battery is showing a voltage reading of fewer than 12.6 volts, your starter is likely not the culprit. If satisfactory voltage is found at the starter’s positive lug, you are likely dealing with internal starter failure, and replacement is advised.

6. No Crank Condition

Turning your vehicle’s key, only to be greeted with silence, is an alarming circumstance to be faced with, and one that can often be attributed to a failed starter. To diagnose this concern, a series of voltage checks must be conducted. First, your vehicle’s battery voltage must be checked for proper charge.

When tested using a digital multimeter, a healthy battery should produce a reading of 12.6 volts. If your battery tests good, you must check the delivery of voltage to the starter, within both the supply and control circuits. The positive lug on your vehicle’s starter should be receiving 12.6 volts, from the battery via positive battery cable. Upon cranking, the control, or “exciter” wire should also receive voltage very close to that which was found at the battery. 

If these readings prove to be adequate, and your starter is sufficiently grounded, you have experienced an internal starter failure and replacement is necessary. Alternatively, if a “clicking” noise is heard when the ignition is engaged, the same series of testing applies when seeking to verify the starter as the root cause.

7. Smoking Of Starter Or Cables

If smoke is observed or a burning smell is detected when upon cranking, your starter is likely on its way out. This can occur as a result of both mechanical and electrical failure. If a condition of this nature is discovered, replacement is essential, as a starter exhibiting these symptoms is not only in poor condition, but can become a fire hazard as well. 

8. Intermittent No-Crank Condition

If your vehicle exhibits a no-crank condition on an intermittent basis, it is likely that your starter is being affected, though an external factor is at play. When symptoms of this nature are encountered, the above-mentioned voltage checks are advised. Less than adequate voltage is a common cause of such intermittent starting issues, with cable corrosion being the number one culprit. If any level of corrosion on battery cables is noted, cleaning is essential.

It is also valuable to consider the circumstances surrounding the occurrence of a no-crank condition. If your vehicle cranks as expected first thing in the morning, only to display inadequacies after an extended drive, it is probable that your starter is experiencing the symptoms of a heat soak condition. This occurs when internal starter circuitry absorbs engine heat, thereby leading to an increase in resistance. In turn, the starter does not operate as it should, until temperature levels subside.

Reasons Starters Fail

Starters are generally quite hearty, exhibiting a substantial degree of longevity. So when a starter fails, it is only natural to attempt to draw a conclusion as to why such a failure occurred. The following are some of the most common causes of starter failure.

1. Faulty Solenoid

In the bulk of circumstances, a starter solenoid will be the most prominent source of starter failure. With prolonged use, contacts within a solenoid become susceptible to burning and flux coating from the transfer of voltage across the circuit as it is closed. This can lead to several issues including the sticking of these contacts or overall circuit failure in general.

2. Prolonged Low Voltage Conditions

Whenever a circuit is deprived of adequate voltage, the components contained within that circuit couldn’t operate as intended. A lack of voltage within the starting circuit is no exception. When a starter is exposed to a prolonged period of low-voltage, wear can be rapid. When an electrical component is forced to operate under these less than ideal conditions, damage occurs with time, stemming from increased heat build-up. 

3. Excessive Cranking

Under certain circumstances, operator error can play into a starter’s longevity or lack thereof. If a starter is used outside of the operating condition in which it is intended, its life span will suffer. Circumstances such as excessive cranking during other no-start conditions or engaging a vehicle’s ignition switch when an engine is already in operation, all play a part in premature starter failure.

4. Fluid Leaks

The reality is that a starter lives its life in an inhospitable location. Heat, vibration, and voltage fluctuations are all conditions that do a starter no favors in its bid for survival. However, little has as much of a negative effect on starter longevity as becoming saturated in leaking oil or coolant. When a starter is constantly exposed to fluids of this nature, both mechanical and electrical components within suffering.

5. Normal Wear

Try as a man might, we have yet to engineer any mechanical component to be impervious to wear. The universal truth is that with years of use, even the most robustly engineered starter will fall to fatigue. No amount of care can prevent eventual wear of internal starter components, and when this eventual failure occurs, a trip to the local parts counter will be in order.

How To Verify Starter Failure

If your vehicle is exhibiting any one of these symptoms, and you suspect starter failure, such concerns can be verified by conducting a bench test. Though you must remove a starter from your vehicle before conducting this test, doing so will give you peace of mind in knowing that your assumption was correct, while also minimizing the risk of misdiagnoses. The following procedure will help guide you through this process.

1. Starter Bench Testing

  1. Remove starter from the vehicle
  2. Place starter in vice
  3. Connect jumper cable ground leads between the negative post on a 12-volt automotive battery and the vice containing your starter.
  4. Connect positive jumper cable leads between the positive post on a 12-volt automotive battery and the large positive lug on the starter.
  5. Use a jumper wire or screwdriver to jump current from the starter’s positive lug to the stud where the control circuit wire is normally connected when in use.
  6. Observe the results of this test. If the starter is in proper working order, an audible click will be heard, the pinion gear should lunge forward, and rotation of the pinion gear should be observed. An absence of this signifies a starter or starter solenoid that has failed.

2. Pinion Gear Inspection

Additionally, while a starter is dismounted from the vehicle, it is advisable to inspect its pinion gear teeth for wear. This is relatively easy to do, as a quick glance with a flashlight will often tell you all you need to know. Look for any chipped, broken, or else wise damaged teeth on the pinion gear. All teeth should look uniform to one another, with no visible diagonal erosion. If any such signs of starter wear are observed, do not reinstall it in this condition under any circumstances. Damaged pinion gear teeth can quickly lead to flywheel damage and wear. When this occurs, you have a much larger problem on your hands.

How to diagnose stater problems

Staying In The Know

By familiarizing yourself with the common signs of a failing starter, you are better able to avoid costly tow bills and further damage to vehicle components. Starter replacement is often easily accomplished by the avid at-home do-it-yourselfer. However, the first step to repairing any problem is identifying its presence in the first place. When you remain in the know about starter failure symptoms and diagnoses, you are only an afternoon’s worth of wrench time away from having your reliable daily driver restored to her former glory.


By understanding these signs of a bad starter, you can make timely repairs, saving hundreds of dollars on tow bills and additional damage.

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Tim MillerFounderOBD Advisor

I’m Tim Miller from Denver, Colorado. I’m the founder of obdadvisor.com, an automotive blog about "Auto Diagnostic Tools and Repair Guides". My fan page is facebook.com/autozikcom. I've been working as an automotive mechanic and blogger for over 10 years writing articles to share my experiences and expertise.

Web: https://www.obdadvisor.comEmail: [email protected]
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