Engine knocking occurs when the gasoline burns unevenly and the shocks activate at the wrong moment. After every pocket burn, it produces a little shock, which ignites the next pocket & the cycle continues.
When gasoline burns incorrectly in your engine’s cylinders, it causes knocking. The engine knocking sound is a pinging, tapping sound that gradually increases in volume as you speed up.
Fuel burns in regulated pockets, rather than all at once when cylinders are appropriately balanced in air and fuel.
This fuel-air charge is only supposed to be sparked by the plug at a specific moment in the piston’s strokes. You must note that knocking is not the same as pre-ignition; they are two distinct phenomena. Pre-ignition might be preceded by knocking.
On the other hand, knocking happens when the combustion process’s peak no longer occurs at the optimal time for the four-stroke cycle. Going further, let us discuss the causes of engine pinging sound or engine knocking.
Why Does An Engine Make Knocking Sound?
Knocking occurs when the gasoline in the cylinders ignites early. This early ignition interrupts the motor’s smooth spinning.
The accidentally fired piston then exerts a rearward push to the shaft against the engine’s motion, resulting in the knock and ping you hear and a tiny pause that results in a loss of performance.
Engine knocking can cause damage to the piston head, cylinder walls, or shaft bearings, which are all costly to replace.
Digital computer injection systems may modify your fuel-air mixture to avoid knocking, but this comes at the expense of engine efficiency. In this situation, decreased fuel economy indicates that the vehicle needs care.
What Causes Engine Knocking When Accelerating?
Before we learn what causes engine knocking, let us first know how ignition happens in normal combustion. The engine burns the air/fuel mixture consecutively.
At the same time, the combustion is started by the spark plug some 10 to 40 degrees prior to TDC (top dead center). The Spark across the spark plug’s electrodes produces a kernel of flame. This kernel grows in size and temperature.
There are various causes of engine knocking sound. You may experience a knocking noise when accelerating from a stop or a knocking sound under a car when braking. Let us discuss things that may cause engine knocking sound:
Too Low Octane:
Every engine is designed to work on a certain number of octanes. This octane number determines the tolerance of fuel to pressure rise. The higher the octane number, the more the piston moves toward the spark plug, producing more power output.
When the octane number is low, make several pockets of exploded air/fuel mixture before the piston reaches the maximum level of travel. This, therefore, results in producing a knocking sound and also reduces vehicle performance.
Bad Timing:
To make the spark fire in an organized manner requires the computer distribution of the electricity from the ignition coil. If this fails to happen, it leads to detonation, which results in the engine knocking when accelerating and the speed rising. In this case, the car starts but stays not running.
Lean Air/fuel Mixture:
If you have a lean air/fuel mixture, it means that the percentage of the fuel is too low compared to the percentage of the air in the AFM.
This happens when there are faults in engine management sensors such as oxygen sensors, spark plugs, spark plug wires, fuel injectors, and mass airflow sensors of the fuel pump.
Without enough fuel in each cylinder, the mixture burning time will be incorrect, causing the mixture to explode at the wrong time. This finally results in producing some detonations causing the engine to knock.
Bad Knock Sensor:
Modern cars equipped with an engine knock sensor detect some faults and send a message to the ECU to solve the problem. If there is a problem with the knock sensor, it will not detect the knocking, and the ECU will not know that there is an error to work. This eventually causes the engine to knock.
Faulty Spark Plugs:
As we all know, spark plugs are essential for burning air/fuel mixture to provide the necessary power for the engine to run. Spark plugs age or gets damaged in time, causing them to produce weaker Spark. At times the spark plugs may delay the sparks making the engine produce a knocking sound when accelerating.
Carbon Deposits:
All the fuel used in cars has carbon cleaners. They help to prevent carbon deposits from buildup and clogging the cylinders. When carbon clogs or buildup in the cylinder, there is less space for air/fuel to reside, resulting in engine knocking. We recommend using the FTI Carbon Cleaner Washing Kit; you Can Easily do the job.
Low Oil Level:
Another reason may be due to the engine knocking low oil. In case the level of oil is below a certain level, the rod bearing between the crankshaft and the piston rod begins to develop a gap. This causes a rattling noise while going up and down.
How to Fix Engine Knocking
Here is Some point to fix Engine Knocking:
Improve The Fuel
A high-performance engine requires high-quality gasoline. If your machine makes a knocking noise, you should know right away that the cure for engine knocking is quality fuel supply.
Ensure that you use high-octane fuel to ensure the situation does not worsen. It ensures that the ignite is performed at the appropriate moment. To stop engine knocking, you may also apply the finest oil additive.
Change The Spark Plugs.
Another thing to consider when we witness the engine banging is spark plug issues. Depending on the kind and frequency of use, it produces banging noises. Experts recommend replacing them once the car has travelled 30 thousand kilometers.
Clean The Battery Terminals
A car making ticking noise could signal that the battery terminals need to be cleaned. Corrosion on the terminals can cause a loss of electrical contact, leading to many problems, including a loss of power and a clicking noise.
The best way to clean battery terminals is with a solution of baking soda and water. Mix a teaspoon baking soda with a cup of water and use a cloth or brush to scrub the terminals. You may also visit a car service in Perth.
Replace The Crank And The Bearing
To resolve engine banging, the crank & bearing must be replaced. It is only sometimes essential, but you should get it examined because these replacements are time-consuming and would require skilled mechanics in Perth for the job.
Examine The Engine Temperature
Another issue that causes engine knocking is engine overheating. So, if everything else appears to be in order, this might be the issue that needs your attention. Firstly, you might begin by inspecting the electric fans.
For all the problems we recommend you to Visit SAI Auto Care. We are one of the most renowned car service station in Perth with one of the most skilled and experienced professionals.
How much does it cost to fix a knocking engine?
The cost to fix an engine knocking when accelerating can vary significantly depending on the cause of the knock.
Ranging from a relatively inexpensive fix like replacing spark plugs or adjusting ignition timing to a major repair requiring a new engine if the issue is a worn connecting rod or piston, potentially costing hundreds or even thousands of dollars.
FAQs.
Q. Can You Drive a Car With a Knocking Engine?
Yes, you can drive your car with a knocking engine, but you have to be gentle while driving. Try to ease up the throttle and check the problem in your vehicle once you get to your destination.
Q. What Does a Knocking Engine Sound Like?
It is like a rapid pinging and a metal clucking while the vehicle is accelerating. At first, you will only hear it while accelerating. As soon as you start hearing the knocking sound, look for the problem, and solve it before it damages your engine.
Q. How Much Does It Cost to Fix a Knocking Engine?
Fixing a knocking engine does not cost a lot of money. At times you will be required to replace the spark plugs, thus adding extra costs. In most cases, it costs approximately $200.
If the knocking sound continues even after changing the spark plugs, the cost will increase since you will be required to disassemble the engine and inspect its internal parts.
Q. Will an Oil Change Stop Engine Knocking?
Ok, you need to differentiate between the cluttering noise from the engine due to too low oil level or pressure and the knocking sound that comes from the combustion chambers. The knocking sound is a result of the problems with Spark and fuel.
Oil change, therefore, will stop the cluttering sound from the valves in the cylinder head and not the knocking sound.
Q. Can Thin Oil Cause Knocking?
Old engines tend to have worn-out engine bearings between the crankshaft and piston rods. When the engine bearings wear out, they make a rattling sound every time the piston moves up or down.
This is called crankshaft knock. Therefore, using thick oil will help to block these gaps and stop the sounds.
Final Words
An engine knocking while accelerating is a problem faced by many people in the course of driving. This sound is not only disturbing to the ears but also has a destructive effect on the engine and its internal parts.
The causes of engine knocking sounds may range from bad fuel, faulty spark plugs, or even a dirty combustion chamber.
The most important action to take has a good diagnosis to ease the repairing process. The prudent thing to do when you hear an engine knocking sound at idle or accelerating is to seek professional advice immediately.
Dealing with the problem early enough protects your engine from future damage.