How can I tell whether a loud noise when accelerating is normal or the sign of a problem?
There are noises that are normal on acceleration. The best way to know if the noise is normal is simply if you have heard the noise before. You have probably driven, or at least ridden in cars for years. Is the noise you’re hearing different than what you’re accustomed to? If the car seems to be excessively loud in general, this is an indication of a problem. There are a number of reasons that a car will make extra noise, all of which are the symptom of a bigger underlying issue.
What kinds of problems would cause the car to make a noise when accelerating?
There are a lot of things that can cause a noise when accelerating. We’ll start with the more obvious ones. The first is belt noise. This often manifests as a squeaking or squealing noise. This noise most often happens when you first begin to accelerate, and sometimes when turning. Belt noise can mean the belt is worn or loose. Belt noise can also come when one of the pulleys the belt is riding on starts to fail. When the belt no longer moves smoothly along the pulleys, it makes a noise when the car is accelerating.
The other noise you might be accustomed to is that of a loud exhaust system. The exhaust system includes the muffler, resonator, catalytic converter, and header/down pipe. The exhaust system carries the exhaust gases from the front of the car to the rear. They are designed this way so you don’t inhale the exhaust fumes and also to quiet the noise engines make. A leak anywhere in this system makes a rather distinct rumbling noise. This noise is more noticeable on acceleration because the engine is working harder, making the noise louder. With an exhaust leak, the muffling of the noise is cut short, making the noise louder.
There are also some more technical causes to point out, without getting into too much jargon. There are a handful of components in your vehicle that are generally referred to as the “drivetrain.” These components include the transmission, axles or driveshafts, transfer case, and differentials. The engine is sometimes considered part of the drivetrain, but we’ll talk about that in a little bit. Any of the components in the drivetrain can wear and start to make noise. The drivetrain is essentially what makes your car go, and all of these parts move when your car is moving. With wear, the parts make contact in a way for which they’re not designed. This in turn makes audible noises. Like exhaust noises, these noises are more noticeable when accelerating because the car is working harder to get you up to speed.
The engine itself can also be the cause of noises when accelerating. As you probably know, the engine is quite complicated. There are many moving parts, and all the parts need to move at the right time in order to make the engine run properly. There are three very important parts we are going to talk about for now, and those are the valves, bearings, and pistons.
- The valves open and close to let in air and fuel and let out the exhaust. When the valves wear they will make a clicking noise. This is most noticeable when accelerating because the valves are moving much faster.
- The bearings are what allow the cam and crankshaft to spin for thousands of miles and millions of revolutions. If any of the bearings fail they will cause a ticking or screeching noise. Again, the noise is more noticeable on acceleration because the engine spins faster.
- The pistons can also wear and make noise. The pistons are what move up and down and make the engine spin. Worn pistons will make a knocking noise — sometimes at idle, and often on acceleration.
Are there makes or models that are more susceptible to noises when accelerating?
Some vehicles are more prone to these noises than others. Any vehicle can have worn drive belt issues. The drive belt is made of a rubber compound and wears out over time. Although all cars have exhaust systems, Hondas are more susceptible to exhaust leaks throughout their life than any other car that we service.
All vehicles have slightly different drivetrain and engine configurations but, with the exception of electric cars, they all have the same basic components. These components will wear and become noisy on acceleration, the degree to which depends more on their usage than the vehicle manufacturer. Due to their engine configuration, Subarus are more susceptible to knocking from worn pistons than other cars.
Is it safe to drive your vehicle when it’s making a noise when accelerating?
Vehicle safety is always very important for you, your passengers and other drivers. Any noise your car makes can be an indication that your vehicle is not currently safe to drive. Many of the noises we talked about don’t pose a direct safety concern, but the end result could be the vehicle abruptly stalling. Always be aware of your surroundings while driving; if your car is making abnormal noises, including only while accelerating, you should have it inspected as soon as possible.
What kinds of repair services can fix noises that happen when accelerating?
- The kinds of repairs needed will depend on the cause or causes of the noise. Belt noises are often easy to diagnose, and with a few exceptions are inexpensive to repair. Once the new belt is installed and the correct tension applied, the car is ready to go again.
- For exhaust leaks, a leak must first be identified, then repaired. Most leaks we encounter require replacement of one or more exhaust components. They are then re-inspected to confirm there are no other leaks and that the new parts seal well.
- Drivetrain repairs, including engine repairs, can be more complicated. In many cases involving the drivetrain, parts need to be replaced. For large components like the engine and the transmission, we’ll source used parts to help keep costs as low as possible.
If you’re experiencing unusual noises when accelerating, don’t wait until things get worse. Book an appointment with a technician to make sure your vehicle is operating safely and identify the cause of the problem.