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What Are The Reasons A Car Vibrates When Accelerating?

What Are The Reasons A Car Vibrates When Accelerating?

Vehicles are complex machines that are comprised of several intersecting systems that produce a seemingly simple act of physics: movement. From the internal combustion engine to the transmission and the actual wheels themselves; a failure in any of these systems can cause a car that vibrates when you hit the gas. It can be a bit of a rabbit hole to find the culprit but with some deductive reasoning and some common sense you can figure it out for yourself. 


 

So what are some issues you may have on your hands if you own a car that vibrates when accelerating? 

 

  • Broken Motor Mounts 
  • Faulty Spark Plugs 
  • Faulty Vacuum Hose(s)
  • Poor Engine Timing / Timing Belt
  • Unbalanced Tires
  • Loose Lug Nuts
  • Bend Axle or Driveshaft 
  • Broken CV Joints
  • Bent Wheel/Tire Flat Spot

 

This article will cover these items in more detail and give you an idea of how much it costs to fix these issues as well. 

Broken Motor Mounts

An internal combustion engine is a raucous and inherently vibration prone invention. Since no one wants to listen and feel the engine as it goes about its business, engineers at automotive manufactures employ the usage of Noise, Vibration, and Harshness (NVH) reducing parts like the humble motor mount. The motor mount is a hydraulic or mechanical dampening devices that isolate the body of the vehicle from the engine by soaking up vibration. Since many cars and SUVs are unibody (the frame and the body are a single piece) reducing vibration is a huge concern. 

 

If these parts fail, they can range anywhere from $350 to $500 for each mount. The location and design of one car vary greatly from the next, so scour the internet for your specific car to find out more. 

 

Faulty Spark Plugs 

 

Since internal combustion engines require spark for ignition, when a spark plug wears out, it will begin to malfunction and cause the engine to vibrate. Every spark plug has an electrode that wears out over time due to the deposit of carbon (a by-product of combustion) upon its surface. Also, older motors often have leaking seals that allow oil into the combustion chamber and this oil can quickly kill a spark plug. Lastly, improperly gapped spark plugs can cause an issue with functionality as every motor has a specific requirement for spark plug gapping. 

 

The cost to fix a spark plug is relatively cheap but replacing an entire motor worth of plugs can run up to a few hundred dollars pretty quickly. Figure around $450 for a full set of plugs. 

Faulty Vaccum Hoses

 

If your vehicle has loose or damaged vacuum hoses, it can vibrate under acceleration. These vacuum hoses operate dozens of different parts in your engine and loose hose can cause an unwanted loss of vacuum and intense vibration due to the engine gulping in air. You’ll want to do a visual inspection of all vacuum hoses in your cars engine bay to see if any are loose or have holes. Listening for air hissing or coating lines in soap can also reveal the issue as well. 

 

This is one of the cheapest fixes there is at less than $10 per hose. Finding the leak is usually the challenge but if you can track it down yourself, it’s a cheap fix. 

Poor Engine Timing/Faulty Timing Belt 

 

When your car leaves the manufacturing plant, the motor is built to an extremely tight tolerance, and over time that tolerance wanes and loosens. If you are not maintaining your vehicle properly with regular tune-ups, then your vehicle will suffer from poor timing and not run smoothly, especially under acceleration. It’s the same story for a faulty timing belt, it can throw off the entire tune of your motor and cause the engine to vibrate and struggle to accelerate. 

 

Replacing a timing belt is best left to the professionals and runs a pretty heft $800 to $1200 depending on your vehicle type. Once the replacement is complete, the timing will also be properly adjusted. 

 

Unbalanced Tires

 

As your vehicle increases in speed, an unbalanced set of tires can lead to a car that vibrates when accelerating. The big difference with this one and the easiest way to rule it in or out is that the vibrations will increase and decrease with road speed, not engine speed. This one is a pretty easy fix and simply requires a trip to your local tire shop for a balance and alignment. 

 

The price for this issue runs a few hundred dollars for both a balance and an alignment. Again, maintain your car and this won’t become an issue that you have to specifically deal with on its own. 

Loose Lug Nuts

 

This is another one of those no brainer type scenarios and it may mirror the same symptoms of unbalanced tires. If your car vibrates when accelerating, one of the first things you should check is to make sure your lug nuts are tightened properly. This can be accomplished with the tire changing kit your car already comes with but you can also take it to a tire shop where they can check it with a torque wrench. 

 

The best part about this one is that it’s a free fix for those willing to check it out themselves. 

Bent Axle or Bent Driveshaft

 

Sometimes we hit a little bump and sometimes we hit a bump that’s so large it damages our axles or driveshaft. For those of us that have had the unfortunate joy of damaging our axles and driveshafts, the feeling is quite familiar to other issues you suspect if your car vibrates when accelerating accept is quite a bit more intense. Specifically, this issue typically shows up in 4 wheel drive vehicles and vehicles that utilize all wheel or 4 wheel drive. 

 

Unfortunately, this is an expensive fix and can range anywhere from $500 to over $2000 to replace an axle or a driveshaft. 

Broken CV Joints

A CV joint is a part that is specific to front-wheel-drive cars. Its basic purpose is to allow the front wheels of a vehicle to steer and power the car at the same time. These parts have a section called the “boot” and when the boot fails, it lets dirt and road debris into the CV joint which leads to its failure. The traditional sign of failure for this part is a clicking or a grinding noise when turning and accelerating but it can also show up as a nasty vibration while under acceleration. This one is especially important to address since it can cause the vehicle to become undrivable in a situation that may put the owner of the vehicle in danger. 

 

Replacing a CV joint is a relatively expensive repair at somewhere around $400 to $600 per side. 

Bent Wheel or Flat Spot On Tire

If you’ve ever had the joy of whacking a pothole on a city street, you know the damage that this can do. Once your rim is bent, it will vibrate as the wheel is now unbalanced during its rotation. In effect, it’s like having a flat spot on a tire and the vibrations caused by this will be quite severe. Vehicles with a low profile tire (performance-based) are very susceptible to this condition. 

 

Similarly, you can also cause vibration at speed by having a flat spot on your tire. If you don’t have ABS or you’ve somehow managed to lock the tires up even with ABS, then your tire will have a flat spot on the tire due to the lock-up. This will cause you some vibration in your entire car as a tire needs to be free of flat spots to function properly. 

 

If this does happen, you’re looking at anything from a cheap junkyard wheel to something that could easily crest $1000 bucks if you have a custom wheel on your ride. 

How About Selling Your Car To Cash Cars Buyer?

Who wants to deal with a car that vibrates under acceleration? There are so many issues that could cause vibration and some of them are incredibly expensive to repair. Rather than deal with the hassle of fixing your car on your own or paying a mechanic to handle it – why not sell it to Cash Cars Buyer instead? 

 

Anyone who’s ever tried to sell a broken car on your own knows the hassle of being lowballed by savvy car buyers who are looking to flip your car for some cash. No Craigslist, no Autotrader, just a seamless process where you get cash and a fair price for your car. We make it easy to get a quote in minutes even easier to get the cash in your hand to buy the car of your dreams. 

 

Stop hassling with that vibrating mess and let us take your car off your hands.