Troubleshooting 101: Why Is My Car Vibrating?

Unless you’re driving an electric car, you expect a bit of rumbling from under the hood, but there’s a big difference between the purr of an engine and vibration that could indicate a problem. If you’re asking yourself, why is my car vibrating, you’re in the right place. If you’re dealing with random vibration, some troubleshooting tips might point you in the right direction. 

Tire Trouble

It always starts with a question. Why is my car vibrating? When you’re dealing with car vibration, the first place to look at the tires. Issues with the tires or rims are among the most common causes of problematic vibration. Look for the following signs on your tires: 

• Missing balance weights — can cause the ties to wobble as they spin
• Damage to the rims — dents, cracks and other damage can throw the rim out of balance.
• Uneven wear — can cause vibration and be a sign of alignment issues.
• Over- or under-inflated tires
• “Out-of-round” tires — when the tire stops being perfectly circular. 

These signs aren’t always obvious. If you’re concerned that your tires are causing the vibrations, take a trip to your favorite shop for a tire rotation and rebalancing. The shop should also be able to spot issues that might not be apparent on a casual inspection.

U-Joint Problems

Rear-wheel drive vehicles use a driveshaft to transmit power from the engines to the rear wheels. The driveshaft is connected by universal joints, otherwise known as u-joints. If these joints dry out or start to fail, it can cause vibration that originates from the middle or rear of your vehicle.  

Vibration caused by faulty u-joints is often worse under acceleration or highway speeds. You may also hear a heavy clunking when accelerating or releasing the throttle. 

Bent Axels

If the vibration seems to be coming from one side of the vehicle, you may have a bent axle on your hands. These small bends aren’t usually enough to cause severe issues, but the bend can deteriorate over time. It can also cause the vehicle to drift toward the bent axle, making it harder to drive. 

Most bent axles are caused by damage to the vehicle. If you hit a pothole, run over a curb or find yourself involved in a collision, it could cause damage to your axels. 

Damaged Motor Mounts

The motor mounts could be the culprit if the excessive vibration seems to originate from under the hood. Most engines have three to four mounts that connect the engine to the car’s frame. These mounts are reinforced with thick rubber that helps to absorb the engine vibrations and keep them from doing damage to the other components. If these motor mounts start to fail — or snap entirely — it can cause severe vibrations. 

This particular issue can be easy to troubleshoot. Start the engine and while the car is in park, have someone press the accelerator pedal. If the engine visibly bucks when they push the throttle, it’s a good indicator of a problem with one or more motor mounts. 

Engine Problems

Motor mounts aren’t the only problem under the hood that can cause additional vibrations. If one or more spark plugs are misfiring, it can cause the engine to buck and vibrate. These vibrations are more apparent in four-cylinder engines but can be equally evident in six- or eight-cylinder engines if multiple cylinders are misfiring. 

You may feel misfire-related vibrations when the engine is idling or when you’re trying to accelerate. You may also experience a loss of power, meaning it might feel like the engine is working harder to achieve the same goal. 

Brake Rotors

If you only feel vibrations when pressing the brakes, it is most likely a problem with the brake rotors. The brake pads press against the rotors when you depress the brake pedal. If the rotors are misaligned or improperly turned, it can trigger moderate to severe vibration. This damage can also happen if you brake heavily or don’t change your brake pads as recommended. 

Vibration while braking isn’t something you should ignore. Continuing to drive could cause additional damage to the rotors, brake pads or other parts of the braking system.

Keep Troubleshooting

If you’re still asking, “why is my car vibrating?” hopefully, these troubleshooting tips can point you in the right direction. Regardless of the cause, make sure you’re addressing these symptoms quickly to prevent any problems in the future.