Can A Bad Alternator Cause Engine to Shake

Can A Bad Alternator Cause Engine to Shake

The alternator is like a little generator in your car. Bad alternator result in various problems for the car. So, can a bad alternator cause engine to shake?

Yes, an engine shake can be caused by a bad alternator. I will show you how.

When I experienced the engine shaking with a bad alternator, I did deep research on it. Finally, I was able to find out how the bad alternator caused the engine to shake. In this article, I will explain it. Let’s dive into the topic: can a bad alternator cause an engine to shake?

Role Of Alternator in Vehicle

Alternator in car engine compartment

You know the alternator is a critical component of the vehicle’s electrical system. Its job is to generate power while the engine is running and charge the battery while providing power to electrical components. The alternator converts mechanical energy, which is generated by the engine’s rotation, into electrical energy.

What Is Engine Shake?

The abnormal vibration we feel while the engine is running is called an engine shake. This can be felt as a rhythmic and pulsating movement both inside and outside of the vehicle.

Engine shaking will be different at various speeds. It ranges from mild vibrations that are slightly noticeable to severe shaking that is uncomfortable for the occupants.

Is It Safe to Drive with Engine Shake?

It is not safe to drive with an engine shake. Engine shake indicates underlying issues that disturb the smooth operation of your vehicle which leads to safety hazards. The root cause of the engine shake is diverse. You need a careful diagnosis to identify the specific reason.

If you continue to drive with engine shake, you will simply wind up causing more damage to your vehicle.

What Are the Reasons for Engine Shake?

There are many reasons for engine shake. Here are them. Let’s find out can a bad alternator cause engine to shake or not.

Engine Misfire

Engine misfire results in engine shake, and this is the most common reason for engine shake. In this case, you will feel the engine shake when accelerating from the ideal position and going uphill.

Uneven Brake Wear

Do you feel the engine shake only when pressing the brake pedal? If yes, the reason is uneven wear on brake pads. This is caused by sticking caliper pistons and a lack of lubrication on the slide pins.

Unbalanced Tires

Vibration at highway speeds (55 to 75 mph) is commonly caused by unbalanced tires. When tires are not evenly weighted, they can create vibrations as they rotate at high speeds. You can fix this issue by balancing tires with weights.

Bad Transmission Mounts

If the vibration is felt only when the transmission is in drive, the reason will be a damaged motor or worn-out transmission mounts. Transmission mounts are designed to prevent engine vibration from being transferred into the cabin. So, if they are broken or worn out, you will feel vibrations inside the cabin.

Worn Motor Mounts

The engine is kept on rubber mounts to isolate vibrations. When they are worn out, the engine can pitch back and forth. This results in shaking.

Worn-Out Tie Rods

In this case, the shaking is especially felt on the steering wheel. You will feel the engine shake when going over bumps and accelerating at low speeds. Worn ball joints in the tie rods cause excess play, leading to steering wheel vibration.

Air System Issues

Vacuum leaks, air hose cracks, and contaminated air filters disrupt the air-fuel mixture, leading to rough idling and shaking.

Fuel System Problems

Fuel system problems cause incorrect fuel delivery. This also results in engine shaking.

Belt Tension Problems

Loose or damaged belts, tensioners, and crankshaft pulleys with deteriorated rubber rings cause engine shake and vibrations.

How Can a Bad Alternator Cause Engine to Shake?

Let’s move to our main topic: can a bad alternator cause engine to shake?

Yes, a bad alternator causes the engine to shake due to an irregular power supply to the ignition system.

As we discussed above, alternators supply electrical power to various components, including the ignition system. So, alternator problems not only cause battery issues but also affect the ignition system, which results in an engine misfire that causes the engine to shake. You can diagnose the alternator by performing a bench test.

Irregular Power Supply to the Ignition System

The ignition system relies on a consistent and precise electrical charge to spark the air-fuel mixture in the engine cylinders. So, when the alternator fails, the engine’s combustion process becomes erratic. This results in an engine misfire. You know that an engine misfire results in engine shake.

Fuel injectors of a vehicle

Furthermore, a failing alternator affects the fuel injectors, as the fuel injectors rely on electric signals. Malfunctioning fuel injectors result in an incorrect fuel-air mixture. A rich fuel mixture results in rough idling and engine shake. A lean fuel-air mixture causes poor combustion and engine hesitation.

What are the Preventive Maintenance Tips to Reduce Engine Shake?

Here are some tips for you to prevent engine shake in the future.

Preventive Maintenance TipsDescription
Regularly Change Engine OilFollow the recommended oil change intervals to keep the engine lubricated.
Replace Air FiltersEnsure proper airflow for optimal fuel efficiency and combustion.
Inspect and Replace Spark PlugsReplace worn plugs to prevent misfires and promote smooth running.
Keep the Fuel System CleanUse quality fuel and clean the system to maintain fuel efficiency.
Check Engine MountsInspect for wear and replace worn mounts to reduce vibrations.
Balance Engine ComponentsAddress imbalances in engine parts for smoother operation.
Maintain the Exhaust SystemRepair damaged components to prevent vibrations and improve flow.
Monitor the Electrical SystemEnsure the alternator and battery are in good condition for stability.
Service the TransmissionFollow the recommended service intervals to maintain smooth shifting.
Check for Vacuum LeaksInspect and repair vacuum leaks to avoid rough idling.
Perform Regular Tune-upsIdentify and address minor issues before they escalate.
Drive SmoothlyAvoid aggressive driving to prevent strain on engine components.
Maintain Proper Tire BalanceEnsure tires are balanced and aligned to reduce vibrations.


Can a bad alternator directly cause an engine to shake?

A bad alternator can indirectly cause engine shake. The alternator is not the direct cause of the vibrations. As we discussed above, engine misfire happens due to the alternator and misfire results in engine shake.

Can a bad alternator lead to other engine-related issues?

Yes, a bad alternator causes electrical issues, battery drain, increased engine load, engine control unit malfunctions, belt and pulley issues, ignition system problems, fuel system complications, and finally, reduced overall engine performance.

What are the types of engine vibrations?

Mainly, there are three types of engine vibration.

  • Unbalanced Vibration
  • Axial Vibration
  • Torsional Vibration

Which engine vibrates more?

Three-cylinder engines often vibrate more than identical engines with four cylinders or more of the same displacement.


Can a bad alternator cause engine to shake? Yes, a bad alternator indirectly causes engine shake, and there are many other reasons for engine shake. So, you should diagnose the issue and fix it as soon as possible as it indicates an underlying issue. You can reduce alternator problems by proper maintenance.

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