Can A Bad Alternator Cause Engine To Shake?

Can A Bad Alternator Cause Engine To Shake?

Have you ever found yourself on the road or in your garage, only to have your engine start shaking and shuddering? This kind of experience can be exhausting and give you a bad driving experience. The issue could be related to various components. So the question is, “Can a bad alternator cause engine to shake?

Yes, a bad alternator can cause the engine to shake, but it’s highly unusual for the alternator to cause a shake or shuddering of your engine.

The alternator’s primary function is to power the car’s electrical system. If it fails to charge the battery correctly can result in engine issues such as shaking or vibration during startup or while driving. 

However, when the engine experiences these kinds of symptoms, it’s not only the alternator’s fault. Various factors and causes may contribute to the shaking or rattling.
In this post, we will discuss bad alternator signs and other reasons that can cause your engine to shake.

What's an alternator

What’s an alternator

A car’s alternator is a device that converts the engine’s mechanical energy to electric energy. The alternator supplies electricity to the electrical component of a car. It produces electricity and helps the battery to charge while the engine is running. The alternator operates by a belt connected to the engine’s crankshaft, converting mechanical energy to electrical energy.

An alternator provides electricity to the battery while charging it and also makes the other electrical components, such as lights, radio, screen, etc., work. It maintains the battery’s electricity level. Because starting the engine needs a massive charge, and the battery needs to be at a certain level to do that. 

A faulty alternator can cause several problems in your car. The Signs of a bad alternator can include dim headlights, a weak battery, decreased driving performance, and the possibility of the engine stalling and rarely causing the engine to shake.

Can a bad alternator cause the engine to shake?

Can a bad alternator cause the engine to shake?

The alternator’s job is to put excessive power into your car. The alternator generates power to spark plugs. If the spark plug misfires, it can cause the engine to shake or vibrate.

If the alternator isn’t functioning properly, it can cause the spark plugs to misfire when starting the engine, which will lead to rough engine performance, which can lead to shaking of your engine.

The problem could also be due to a slipping belt or a faulty alternator. If you’re experiencing shaking or vibration in your car, it’s a good idea to have your alternator to get checked.

You may be interested to read: Car shaking when releasing the clutch in first gear

Signs of a bad alternator

There are many symptoms to identify a bad alternator. Some of them are:

1. Flickering or Headlights Dimming:

If you experience your car’s headlights flickering or dimming when you first start your engine? Well, that could be a sign that your alternator is not generating enough power to keep everything in your car functioning properly. 

This means that your battery isn’t getting charged enough from your alternator while it’s being drained by our headlights which are consuming more power than the battery can provide, causing them to flicker or dim randomly. Check and fix it as soon as possible if you don’t want a dead battery.

2. Dead battery:

If the alternator is bad, it won’t charge your car’s battery. as a result, you will find a dead battery, even after recharging your battery from a different source. It won’t hold charge cause it won’t get charged in the first place. This will cause all kinds of problems like the car not starting, accessories not working properly, and even the engine is dying. If it happens, the alternator must be fixed asap!

3. Warning lights:  

If you happen to notice a warning light shaped like a battery on your car’s dashboard, it could be an indication that your alternator is having issues. This is a common feature in many modern vehicles, and it’s designed to alert you of potential problems with your car’s electrical system. So, it’s best to get your car inspected by a professional as soon as possible if you see warning lights to make sure that your vehicle is running smoothly and avoid any further damage.

4. Strange noises:

If you notice strange sounds like grinding, whining, rattling, or humming coming from your car, it might be a sign of a bad alternator. The alternator bearings may be malfunctioning, which can be causing these noises. To verify that it’s the alternator making the noise, you need to inspect the engine bay sharply and listen for the sounds coming from the alternator.

5. Visual Signs of a Worn Belt:

One of the ways to easily notice a bad alternator is to check without testing it is to look at the belt.

If you notice that your belt looks old, cracked or worn, there’s a good chance that your alternator isn’t functioning properly. An old and torn belt tends to slip more on the pulleys, causing shaking or vibration. This can create a bumpy feeling while driving, which can be both uncomfortable and dangerous. A broken belt can leave you stranded on highways once your battery has been drained out. If you see this issue ask for professional help.

6. The Car Won’t Start:

If the alternator in your car is not working properly, it can prevent your car’s engine from starting because starting your engine needs electricity from the battery to create a spark that ignites the fuel and makes the engine turn on. If the alternator is not providing enough power to the battery, it will run out of charge, and the starter won’t have enough power to turn on the engine. As a result, your car won’t start, and the engine will stall. Fix it before it’s late.

7. Car Shakes While Driving:

As mentioned in this post, a bad alternator will cause the car to shake often. This happens because the alternator belt slips on the pulleys, and also bad alternator causes spark plugs to misfire. If this happens, you should let it checked by a professional.

8. burning smell:

Your car’s alternator is responsible for producing a lot of power for your car, but it also generates heat because the parts that spin inside it are at high speeds. If you notice closely, The alternator’s case is well-ventilated, and the case is well-packed with air vents. This causes heat to escape and lets the chamber inside cool. 

However, sometimes you might notice some smells coming from the alternator. One smell is an electrical burning smell, which means the alternator is overheating, and the diode may be struggling to change the current. 

Another smell could be a burning smell that’s coming from the alternator bearing, which is caused by the fluid around the bearing, like brake fluid and power steering fluid, to heating up.

9. Cooling System or Air Conditioner Problems:

The alternator provides electricity to all the electrical components that your car has. So the air conditioner on your car is also run by the electricity provided by the alternator. If your car is heated up after starting your air conditioner and it’s taking longer to cool down. This might be due to a bad alternator.

What other reasons could there be for the engine to shake?

What other reasons could there be for the engine to shake?

The shaking or vibrating of your engine could b due to different reasons. Some of the potential reasons are:  

Blocked Fuel Injector

When a fuel injector gets blocked, it can’t mix the right amount of fuel and air into the engine, which causes the engine to run on a thin mixture of air and fuel, which is largely air. 

This blockage can happen due to carbon buildup, which happens when impurities from the fuel tank get beyond the fuel filter and ends up in the engine.

Vacuum Seal That Isn’t Working

If there is a leak in one cylinder, it can cause the air to escape and reduce pressure, making it difficult to ignite the fuel properly. This can lead to the engine shaking and making a hissing or sucking sound.

Spark plugs

Spark plugs were required to get a replacement every 12,000 miles in the older version of cars. But nowadays, they can last over 100,000 miles. However, they can still wear down and build up residues that can cause the engine to shake if they don’t fire properly.

Blocked Catalytic Converter or Exhaust Pipe

When exhaust gases can’t exit the car’s system properly, it can cause issues with the car’s sensors. 

The EGR( Exhaust gas recirculation)valve in your car is in charge of returning unburned fuel from the exhaust to the engine for better fuel economy, but it can malfunction if it gets stuck. A blocked catalytic converter increases pressure in the exhaust system, triggering the DPF sensor(differential pressure sensor) in a diesel car to reduce diesel sent to the engine, which can result in poor performance and shaking of the engine.

Can you drive with a weak alternator?

Driving your car with a weak or bad alternator is not a good idea because a bad alternator can cause many types of problems, which can give you a horrible driving experience. The problems that a bad alternator can cause are 

  1. Your car will face problems when starting. Well, most of the time, it won’t start in the first place because the battery will get discharged and won’t have enough power to start your engine.
  2. The sensors on your car won’t work because they work on electricity, so if the alternator is weak and the battery is out of power, you can face some serious problems while driving.
  3. All the electronics on your car, which runs on battery, such as dashboard engine management, ignition, radio, carputers, telematics, in-car entertainment systems, and others, won’t work.

What to do if Your Vehicle Has Signs of a Faulty Alternator

After implying the methods mentioned above, you can get to know if your alternator is faulty or not.

If the alternator malfunctions or does not work properly, you should consult with the mechanic, or it would be best to take your car to an auto repair shop to inspect it thoroughly. They would check your car’s electrical system, spark plugs, and crankshaft pulley and change the oil if needed.

As we know, a bad alternator can cause damage to your car’s electronic system, so it is best to repair it as soon as possible for the betterment of your car.


The alternator is responsible for providing electricity to your car by converting mechanical energy to electrical energy. Doing that helps in running all the electric accessories that your car has. But if your engine is shaking, you may ask, “Can a bad alternator cause engine to shake?

Yes, it can be one of the reasons why your engine shakes, but that is highly rare. A bad alternator is easy to notice if you notice the signs mentioned above. But if your engine is shaking, there might be other problems rather than a bad alternator that’s causing your engine to shake. 

By following the article, you can identify the potential cause of why your engine is shaking. Trust me; I know a shaky engine can be really annoying. If you see the symptoms mentioned above, ask for professional help soon if you don’t wanna see permanent damage to your car.

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