Every vehicle has a starter motor in it. The purpose of the starter motor is to spin the engine fast enough for the engine to run off of its own power. The starter is really just an electric motor that can be controlled by the ignition.
When you turn the key in the ignition, teeth on the starter motor engage with the flywheel or flex plate and spin the engine. The flywheel or flex plate is directly connected to the crankshaft, which pulls air and fuel into the combustion chamber as it rotates. Meanwhile, the spark plugs fire at a precisely calculated interval which allows the fuel inside the combustion chamber to be ignited.
This whole process is crucial for an engine to turn on and function properly. If your starter fails, there is a very good chance you are going to be stranded because you won’t be able to get the engine running again.
Bad Starter Motor Symptoms
It will be easy to recognize a starter motor that has gone bad or is in the process of doing so if you know what to look for. The best thing to do after first noticing these symptoms is to get your starter checked right away.
Below are five common issues to watch out for which indicate that your starter is bad and possibly needs to be replaced.
Warning: when troubleshooting your starter, be careful not to touch the thick wire that connects the positive terminal of the battery to the starter. This is a “hot” (active electrical current-containing) wire that may shock you. It’s best to disconnect the battery when working on the starter.
1) Vehicle Can’t Start
This is the most obvious clue. If you turn the key in your ignition and the engine won’t turn over, then the starter solenoid may be damaged or worn out. Check the small electrical connector to the starter and make sure it hasn’t come unplugged (which can happen due to vibrations in the vehicle over time).
If you drive an automatic, you might want to check your neutral safety switch as well. This is located in one of two places depending on the linkage type of the transmission: either inside the transmission itself or on the column of the shifter (below the console assembly). This switch is there to make sure the vehicle doesn’t start when the shifter is in gear (in some position other than park or neutral).
2) Smoke from Engine Bay
If your vehicle is producing a lot of smoke, then there might be a short in the starter. This will cause a release of gray or black smoke from under the hood because the involved wires are heating up more than they are designed to.
A short refers to a short circuit, where electricity passes from a live or “hot” wire through to a neutral wire (because it’s too close or actually touching) which completes the electrical circuit too early, bypassing the actual appliance (in this case, starter motor). This neutral wire is not designed with enough resistance that “slows down” the current of electricity, so too much current passes through the wires and they heat up sometimes to the point of burning, causing smoke.
3) Grinding Noise
A series of gears connects the flywheel and the starter together. Both components can cause grinding noises when they get too worn out. A bad starter motor will have grinding noises coming from inside of it and worn out gears will also cause these noises too.
Some failing starters may keep the starter gear engaged with the flywheel or flex plate even after the engine is running. This may cause a grinding noise or sound like the car is still trying to start, even when the car is already running.
Either way, turn off the car immediately to prevent further damage. Bring the vehicle to the mechanic to investigate which issue is causing the grinding noise.
Related: What Does a Bad Starter Sound Like?
If there is no cranking coming from the engine and you start to hear a whining noise coming from the starter, this is a symptom known as freewheeling. This indicates that the starter motor is spinning the starter gear but cannot make contract with the flywheel.
The starter solenoid is responsible for pushing the gear on the starter forward so it can engage with the flywheel or flex plate. Freewheeling may occur if the starter motor is able to spin, but the starter solenoid has failed.
5) Burning Smell
Whether you see smoke coming out of your car or not, a burning smell inside and outside your car when it is turned on can be an indication that your starter is bad. Most of the time with this issue, the smoke and the burning smell will occur at the same time.
There are many other issues that can cause a burning smell in and around your vehicle, but some can lead to dangerous situations (such as a car fire or brake failure) so take this smell seriously and don’t drive the car until the issue is diagnosed. Faulty wiring, issues with brakes or clutch, debris or broken HVAC, or dripping oil from a leak are some potential causes of the foul smell.
Will a Bad Starter Still Crank?
Cranking is the repetitive chugging or sputtering sound that the engine makes for a couple of seconds while you turn the key. This happens while you turn the key in the ignition and hold it in the “start” position.
Like all mechanical parts, starters wear slowly over time. Unless something causes the starter to suddenly break, there will usually be issues starting the car before it completely stops working. Eventually the starter may not crank at all (so the engine is not turning over). So, a bad starter could still crank but it may not. If your starter solenoid is bad, the starter will not crank the engine even if the starter motor is still good.
Starter Motor Replacement Cost
The starter is positioned near the intersection of the engine and transmission so it can be difficult to access on certain models. The cost to replace a starter motor will depend on the repair shop or dealership that you bring your vehicle to as well as the make and model of your vehicle; some starters are much harder to access than others.
You can expect to pay anywhere from $250 to $1500 in total to replace your starter. The parts will usually cost between $100 to $400 and the labor costs can range from $150 to $1100.
While this issue can be expensive to repair, it’s vital to take care of right away. After all, if the engine can’t predictably start, then you might not be able to drive the car at all or may even be stranded somewhere.
How to Extend the Life of Your Starter
1) Clean the Connectors
The battery and starter motor are connected through a series of special connector wires. If there is corrosion or any other type of dirt or grime on the connectors, it will limit the strength of the electric current that gets sent to the starter relay.
This could make it impossible for the motor to generate enough power to fully crank the engine. It could also ruin the integrity of the motor, causing it to become excessively worn out.
To clean the connectors, you must first disconnect the battery. Spray off any visible dirt or dust with compressed air. Apply a small amount of rubbing alcohol or acetone to help break down other debris, or use a specialized solution for electrical contact cleaning(which often comes with a handy sprayer to reach tight places). You can use a pencil eraser or small square of fine sandpaper to remove debris so that the surface is shiny again, but make sure to remove any sanding residue with alcohol or a clean toothbrush before reattaching the connectors.
2) Tighten the Mounting Bolts
The starter motor is held in place with mounting bolts. If these mounting bolts become too loose, then the drive of the starter and the flywheel won’t be able to engage properly with each other. One symptom of this is a grinding sound whenever you try to start the engine.
To prevent this from happening, you should periodically check to make sure the mounting bolts on the starter motor are tightened (torqued) to spec. They can loosen over time as the starter is used again and again to start the car, since the starter motor has a lot of torque that puts pressure on the bolts and vibrates the housing.
3) Clean the Starter Solenoid
The solenoid is often confused with the starter relay (the starter relay refers to the electrical component that transmits the power to the solenoid when you turn the key). The solenoid sits as a small cylinder on the top of the starter motor. There is usually a small electrical connector that plugs into the starter, and that is for the starter solenoid.
The solenoid needs to be cleaned and maintained on a regular basis (always disconnect the battery first to ensure safety). All dirt, corrosion, and debris from the solenoid must be removed.
4) Clean the Terminals
The battery terminals are notorious for getting covered with corrosion – a white, blue, green, or teal powdery substance that tends to appear on old batteries. Regular use of the battery causes hydrogen gas and other electrolyte gases to vent to the outside of the battery, and they can interact with the metal there to create corrosion.
Corrosion occurs faster when the battery has been used for a long time (even a couple of years if used regularly), was overcharged, or maintained or stored improperly. When the terminals are covered with corrosion, the electric current which gets sent from the battery to the starter motor is weakened. Since a lower electric current is not what the starter motor was designed to use, this can damage the motor over time.
Cleaning the battery terminals is relatively easy. Make sure the car is cool enough to work on (hasn’t been driven in at least 30 minutes) and that you are working in a well-ventilated area since battery fumes are usually toxic. Gloves and eye protection are recommended.
First disconnect the battery cables: black, then red. Then apply a paste of baking soda and water and allow it to sit for a few minutes to allow the chemical reaction to neutralize the battery acids in the corrosion to take place. Alternatively, you can sprinkle baking soda onto the corrosion and sprinkle water over that. Then use a dry paper towel to remove any corrosion/baking soda debris and clean it well, using a scrubby sponge if necessary. Replace the battery cables in reverse order: first red, then black.
5) Inspect the Flywheel
The flywheel is a rotating device which assists the starter in cranking the engine. The front side of the starter has something called a pinion gear. This is the gear which engages with the flywheel so that the engine can be cranked.
Both the teeth of the flywheel and teeth of the gear need to be in good condition. If these teeth are cracked, worn, or missing altogether, then your starter motor cannot properly contact the flywheel to do its job and start the engine. You will need to replace the flywheel or pinion gear if their teeth are causing the problem.
Continuing to force the engagement between the two (continue to try starting the car) while either or both are broken or misaligned could wear out the starter motor more quickly.
Starter vs Starter Relay Failure (Diagnostic Test)
If the starter is the culprit, the problem could be mechanical or electrical in nature. This will depend on whether the root cause lies within the starter motor or the starter solenoid. If you can eliminate mechanical failure as a possibility, it will be easier to find the source of the problem.
You can test if the starter works by running power directly to the starter along a wire from the battery, bypassing the starter relay and the starter solenoid. This can be dangerous and can damage the starter by providing too much electrical current if you are not careful. Bypassing the starter solenoid, relay, and connecting wires like this will quickly tell you whether you have a mechanical problem with the starter motor or an electrical problem with the starter solenoid or starter relay.