It is not a pleasant feeling when you hear rattling and knocking sounds from under the hood. Especially when accelerating. Most drivers always create catastrophic scenarios in their heads. That is followed by thoughts about money needed for a mechanic. But don’t overreact. Check what can be the problem first.
So what are the most usual reasons for a knocking sound when accelerating? Adding low octane fuel type if your car needs a different fuel is the common reason. Also, problems with spark plugs, dirty injectors, or worn-out engine parts can point out the same problem.
Wait, don’t go yet! In this article, we will cover all the reasons for the knocking noise coming from the engine. Also, we will describe all the symptoms to look out for. And you will also learn what you can do to stop knocking noises.
Causes of Engine Knocking when Accelerating
There are several causes for this problem. Most of them revolve around fuel and engine maintenance. When you hear a knocking noise, think about these causes. Between them, you may find what makes a problem for your engine.
Low-quality Fuel
The most common problem that causes knocking engine sounds is low-quality fuel. If your car is rated for premium fuel, and you are using regular, then you may hear a rattling sound from your engine.
Premium fuel has better characteristics and will stay stable at higher temperatures. Some engines are designed to use it because they combust at a higher temperature. That’s why you will rarely have this problem when you are using high-octane fuel.
Incorrect Octane Level
This problem comes with the previous one. Before adding fuel, check what type of fuel the manufacturer recommends for your car. Some cars use high-octane fuel. Using the wrong octane-level fuel will cause problems.
Carbon Build-up
Carbon tends to build up around pistons, spark plugs, and valves, in the cylinder walls, and the combustion chamber. Even if you use additives as an engine cleaner, the build-up can still happen.
When a build-up of carbon occurs, that will make the combustion chamber smaller. That will make the firing of the spark plugs less effective. Carbon deposits can also create hot spots that can light up the mixture of air and fuel before the spark plugs.
Worn or Damaged Parts
Several engine components can create knocking noise. If they are damaged or worn, you should replace them to prevent further problems. Parts that can make this problem are:
- spark plugs
- worn bearings
- bad knock sensors
- engine timing belts
Spark Plugs
Spark plugs create sparks in the combustion chamber. This way the mixture of air and fuel is ignited creating an engine power stroke. Faulty spark plugs, or plugs of the wrong type, can cause a knocking engine sound.
Bearings
Bearings that are between the crankshaft and the engine turn millions of times in their work life. Engine bearings wear can be a reason why there is a loud noise coming from the engine. Ask the mechanic to check and replace them if needed.
Knock Sensor
The engine has a knock sensor that communicates with the Engine Control Unit (ECU). ECU handles the air-fuel mixture, the fuel injectors, and the timing of the ignition. If there is any knocking, the sensor sends that info to the ECU. If the knocking sensor is working properly it will resolve this problem instantly. If not, the sensor is in trouble.
The Timing Belt or Chain
The timing belt or chain (depending on the car) can cause noise when accelerating. The belt is connecting the crankshaft and the camshaft. It handles the proper timing of pistons. The pistons should move at the same time as the intake and exhaust valves open and close. If the timing is not correct, then can create the misfiring of the plugs, creating engine noise.
Poor Engine Maintenance
Low oil is a common cause of engine knocking sounds. Always be on the lookout for a low oil pressure indicator. Also, change the oil regularly. The intervals for an oil change are mentioned in the car’s manual.
The Spark plug’s age can also be a problem that can create a clunking noise from the engine compartment. Consult your car’s manual and the mechanic. That way you can learn the time interval for the replacement of old spark plugs.
Check Out (SOLVED)Engine Knocking or Tapping Sound That Varied With RPM:
Symptoms of Engine Knocking
Several symptoms can be a warning signal that the engine knocking sound is a serious problem. Besides the different noises, there are other things to look out for. The obvious ones are loss of power and problems with acceleration. Also, a warning light glowing on the dashboard is an important signal.
Loud Knocking or Ticking Noise
If you notice unusual loud knocking or ticking noise that is a major symptom that your engine is in trouble. Depending on the troubled part, the sound will be different. Pay attention if you hear sounds of metal colliding and crushing. That can point to major problems. You should stop the car as soon as possible, and contact the mechanic.
Reduced Power and Acceleration
A harder knocking noise is usually followed by a loss of power and acceleration in the everyday drive. That can point to the ignition timing being off. Checking the spark plugs and pistons is a good way to diagnose this problem.
Warning Lights on Dashboard
If the warning light turns on the dashboard, that can be a symptom of many problems with the engine. If there is a warning light on the dashboard, and you hear a rattling noise, it is time to visit the mechanic.
How to Diagnose Engine Knocking
Most drivers can only do the basics for diagnosing engine-knocking problems. We will point it out to them, but we will recommend visiting the mechanic for any extensive problems.
Checking the Octane Level of Fuel
This can solve a lot of problems. If you are using low-octane gasoline that can be a reason for a knocking noise when accelerating. Check the manual for your car, and use the recommended fuel.
Inspecting the Engine and Its Parts
If you have experience or knowledge of car mechanics, you can take a look under the hood to check for any visible problems. You can check the spark plugs or the timing belt for wear, and signs of old age.
Running Diagnostic Tests
For this, you will need a professional OBDII scanner. When connected to the car’s computer it will get information from all the sensors. If there are any problems, the scanner will show the error and you will need to check it in the manual.
What Does Engine Knock Sound Like
Several knocking sounds sound a bit different. People compared those sounds with these:
- metal balls colliding
- a quick knock on the door
- a pencil tapping on a piece of wood.
Some problems will increase and others will go away, depending on the situation. If the rod bearing is the problem, the sound will increase when the car accelerates. If the sound decreases when the engine is idling, the problem can be in the exhaust gaskets.
How to Fix Engine Knocking
Engine knocking is in most cases the result of the use of the wrong type of fuel, or from lack of regular maintenance.
Correcting Octane Level
Always use recommended octane-level fuel for your car. You may use cheaper fuel, but in the long term, you will pay more for the maintenance of the car. Check the owner’s manual for the car for all information on fuel use.
Regular Maintenance
Knowing the intervals for regular maintenance is essential for keeping the car in working order. Changing oil and filters is very important, and you should do it regularly. Spark plugs and a timing belt have to change intervals that need to be followed.
Key Takeaway: Regular maintenance will keep most problems from your car away. It is relatively cheap and will prevent further expenses.
FAQs
Why Does My Car Knock When I Accelerate
You can start by checking the octane level. Switch to one that is recommended. If that doesn’t help, change the oil and the oil filter. Next in line are the spark plugs. If this doesn’t fix engine knocking, then the problem can be in worn bearings or faulty rod knock sensors. Replacing these will need the help of a professional mechanic.
What causes the engine to ping?
The three most common causes for the pinging sound are low-octane fuel, carbon build-up in the combustion chamber, or a misfire of the spark plug.
Will a low transmission fluid level cause the car to jerk?
Yes, it can cause it. A car can jerk if the oil level is low, or when the oil is old. Tend to this problem sooner rather than later. If you leave your transmission with this problem, the cost of repair will grow over time.
Is engine knock serious?
It all depends on the type of knock. It can be benign and easy to solve, like changing the fuel type or replacing the oil and its filter. But if the engine has many problems due to poor maintenance that can pull a lot of money from the pocket to solve.
What Can Be Mistaken for Transmission Problems?
Several symptoms can be wrongly diagnosed as transmission problems:
– Burning smell – it can point out an oil leak, a problem with the AC, a faulty clutch, or a brake
– Gear trouble – a clogged catalytic converter can cause problems with shifting gears. Also, oxygen and airflow sensors can make the same problems
– Weird sounds – humming and clunking sounds point out the problems with the transmission. The rest of the knocking sounds can relate to the engine problems.
Final Considerations
If you know what can cause strange sounds in your car you can save a lot of money and nerves. Usually, the problem is in the type of fuel used, and its octane rating. Also, frequent problems are with oil and bad spark plugs.
Either way, we recommend that once they hear anything unusual go to the mechanic. Diagnosing these problems can be difficult. There are different parts to look at and check. Certified mechanics will know where to look, and in the end, how to solve the problem.
Keep your car well-maintained, and regularly check our blog for advice!
