Why Is My Car Shaking?

Sometimes a car vibrates from the engine compartment, because the engine isn't getting the proper amount of air, fuel or spark that it needs to run smoothly.

Symptoms that might indicate such an engine-related case of the shakes include the following:

These symptoms could be signaling that you have worn spark plugs and it's time for a new set of spark plugs. If the plugs are fine, it could be that the spark plug wires need to be checked (are they connected in the proper order?) or replaced.

Also consider that a dirty air filter or clogged fuel filter can starve the engine of needed oxygen or fuel, respectively. These filters are inexpensive and easy to swap out, so take a look at your owner's manual and be sure to replace filters at the manufacturer's recommended intervals.

Motor mounts, or engine mounts, are the parts that keep your car's engine in place. If you've ever poked around under your hood, it might look like the engine is held in place simply by being wedged in there. In reality, it's secured to the car's chassis by motor mounts, which can vary in appearance based on the size, shape and strength needed for any given car.

Motor mounts are usually made of metal and rubber, and can be found nestled between the engine and the "frame" of the car. (The term "frame" is used loosely here, because the engine's specific location within the engine bay determines where it will bolt up, and that is a little different for every car.) In other words, the engine will always be bolted to structural components, though those components vary based on the vehicle's design.

The metal in the motor mount provides the structural integrity needed to hold everything in place, and rubber helps absorb the engine's vibrations. Of course, both of these materials wear out over time, and motor mounts need to be replaced periodically. When the motor mounts are worn, the metal is no longer providing a firm brace between the engine and the chassis, and the rubber is no longer absorbing all the vibrations. It's as likely a reason as any that you might suddenly or gradually notice shaking in your car's front end.

If you have a high-performance car or a car that has been modified, you might have high-performance motor mounts, which are made of a firmer material and don't absorb as much vibration. There's nothing wrong with firmer motor mounts, but some drivers find them annoying.

Loose engine mounts could be giving your vehicle the shakes, but what if your entire vehicle vibrates only when you apply the brakes?

Do those bad vibrations appear or intensify when you apply the brakes? Is the steering wheel shaking? If so, there's a strong possibility that your car is tooling about with warped brake rotors.

The rotor is the shiny, silver disc-shaped component on vehicles with a disc brake system. The rotor can get bent out of shape due to heavy wear and tear — basically, overheating from more stopping than that particular rotor can handle. Instead of being uniformly flat all the way across, a deformed rotor is raised or lowered on part of its surface. The calipers and brake pads, which squeeze the brake rotors to make the car stop, can't get an even grip on a warped rotor. Hence, vibration.

Worn out brake pads could also be the culprit. If you're not handy with a wrench, it's a good idea to see a brake specialist who can tell you the condition of your vehicle's rotors or brake drums (on cars with rear drum brakes).

Our vehicles are full of reciprocating, rotating parts that have to fall within certain measurements, or tolerances, in order to perform properly.

If an axle gets bent — which is actually quite easy to do in a collision or other mishap — it will create a jostle of a ride afterward. With this problem, the vibrating often picks up in intensity the faster you drive.

A related problem would be that the driveshaft also needs inspection. This rapidly spinning part transfers engine power to the rear axles and wheels in rear-wheel drive vehicles. If it's bent, it can cause shaking.

Worn-out constant velocity (CV) joints fall under the same category. If the "boots" — those rubber, accordion-like coverings around the ends of the drive axles — are intact, clamps are secure and no lubricant is seeping out, chances are they're not the problem. But if the boots are torn, that means dirt and dust and road filth are getting in and damaging the joints. For front-wheel drive cars, toasted CV joints mean you'll be buying new drive axles, too.

If you've ever driven a new car and an old car back to back, you might notice that the steering in the new car is much firmer and more responsive than the old car. In other words, the newer car will respond more quickly to the way you turn the steering wheel, and the amount the car turns in relation to how much you turned the wheel should feel more accurate. (One caveat here: Different types of vehicles are deliberately engineered with different types of steering responsiveness, so this little exercise loses its significance if you're comparing, say, a sports car and a limousine, regardless of their ages.)

The point of this example is to explain that steering components, like many other parts on your car, can wear out, and since it happens so gradually you probably won't even notice. There are a lot of little moving parts that physically connect your steering wheel and the four wheels on the ground, and once those parts start to wear out, your wheels won't do exactly what you tell them to do. Your car will still steer (provided the parts aren't totally shot), but the excess play in that complicated network can cause vibrations.

These components are best left to the professionals, so keep this possibility in the back of your mind if you have an older car and the other potential solutions in this article prove fruitless.

If your car shudders or vibrates only when you're turning, it's a little easier to narrow down the source of your problem, since it is probably from the power steering system. Take a look at the power steering system's hoses to see if there are any visible leaks, and check the reservoir to see if the power steering fluid needs to be topped off.

You can also try to replicate the sound while the car is not moving. According to YourMechanic, if the problem is somewhere in the power steering system, you should feel the same vibrations from turning the steering wheel even while the car is in park.

Sometimes it isn't your car's tires, but rather the wheels that the tires are mounted on that cause your car or truck to vibrate when driven.

Have you ever noticed little metal squares, that look a little like small refrigerator magnets, stuck along the edge of your car's wheels? Those are wheel weights, and they're used to balance your wheels. If you want to take a look, turn your steering wheel as hard as you can to one side (when your car is parked) so your wheels turn outward. It's not uncommon for wheel weights to be mounted on both the inside and outside of the wheel.

While you're in there, if you notice any mud or other debris clinging to your wheels, wipe it off.

Unbalanced wheels are a common cause of car vibration, and though this is a difficult problem to diagnose on your own, it's fairly inexpensive to have a shop check out and balance for you.

If an unbalanced wheel can cause vibrations in your car, any damage to your wheels certainly can, too — and it might be more common than you think. Watch out for potholes and sloppy road repairs, which can both be equally hazardous to your wheels. Even a little bump that you immediately forget can be enough to throw your wheels out of round.

Another thing to look for is "runout." This is the term that describes how much a wheel deviates from a perfectly circular rotation when it is spun. Wheel technicians use precision instruments to determine if runout on any particular wheel exceeds half an inch. Much of the time — but not all the time — the solution is a new wheel.

Wheels prove to be a common culprit when you are looking for reasons for why a car is vibrating. But we can narrow it down even more. For our top reasons your car is vibrating, go to the next page.

Tires are often the cause of your car's moving vibrations, so the next two pages will examine different tire problems and how they can affect the way your car runs.

Low rolling resistance tires, also known as low-profile tires, are becoming increasingly common along with the rise in hybrid cars and EVs. These tires reduce drag and resistance, which in turn boosts the EPA fuel economy rating, a critical measure for these types of vehicles, particularly from a marketing standpoint. However, low rolling resistance tires are harder than most drivers are used to, and simply aren't pleasant to drive on because they don't absorb much of the road's imperfections.

Even though they're also referred to as low-profile tires, that term can be confusing because the "low profile" may also be attributed to other performance tires. In either case, you're looking at tires that have less material, or harder material, and therefore tires that are less able to absorb bumps, pits and texture on the road.

If your car is equipped with low-profile or high-performance tires, that could be the source of your vibration problem. However, it's best to eliminate other potential causes.

Old, dry, bald or worn-out tires are a very common source of excessive road vibration. The tires are the only part of your car that actually make contact with the road, and they're known for having a relatively short lifespan.

The full list of ways in which tire issues can contribute to your vehicular shake, rattle and roll is a long one. But here are just some of the major ones:

Also, keep in mind that these 10 reasons your car is vibrating aren't the only possible culprits. When in doubt, it's always a good idea to see an automotive service professional. For more information about diagnosing car problems and other related topics, follow the links on the next page.