Car making noise after engine turned off is something that can make you worry. The answer to this repeatedly asked question can be radiators, coolant leakage, or loose car parts.
In this guide, we have jotted down all the possible reasons that can lead to car noises. You will also find some quick fixes to stop the noise.
Contents
Why Is Your Car Making Noise After the Engine Is Turned Off?
Your car makes noise after the engine is turned off because of the cooling system, leaking gasket, or unlinked parts. Sometimes the noise comes due to hot coolant, evaporation system, or headlights. Low lubricant levels also lead to engine heating and noise.
– Noise From Radiator
Most modern-day cars have smaller engines, and because of that, they put more force to function. They have parts made of different metals, such as steel or aluminum, so each of them takes a specific time to cool down.
The exhaust or radiator of the car keeps working until all the components cool down. So if you are wondering “Why does my car sound like it’s still running when turned off?” the radiator might be working. The cooling system usually takes longer to cool the engine on hot days or after a long journey. It leads to a specific whirring noise after engine off the ignition.
You might be asking “Why does my car make a fan noise when I turn it off?” The car makes a fan noise because of the radiator fan. The fan keeps rotating after the engine turns off the ignition, which happens due to several reasons like clogged radiators or bad fan relay. Other reasons are leakage in the coolant reservoir, worn-out fan wires, and a defect in the temperature sensor.
– Damaged Head Gasket
The gasket is present in the combustion chamber of the engine. It acts as a guard between the coolant and cylinder head. Due to some reason, the gasket might leak, and this causes a knocking sound after turning engine off.
When the gasket leaks, the coolant comes in contact with oil and road contaminants. The oil loses its lubricating property when the coolant is mixed, so the sound emerges because the engine overheats and does not work efficiently.
– Air Entering the Coolant Reservoir
Sometimes air enters the reservoir containing the coolant. It may cause a gurgling or grinding noise when turning engine off. Air seeps in even if there is no damage to the gasket.
The manufacturers usually advise changing the coolant from time to time, so if you have avoided the maintenance of your car for months, the reservoir might have air seepage.
– Hot Coolant Takes Time To Cool Down
The coolant runs through different engine compartments to cool them. During this process, it heats itself, so the radiator has to cool it. But if you stop the car before the coolant cools, the hot coolant stops flowing. If everything else seems fine, this might be the answer to “Why is my car making noise after engine turned off?”
The hot coolant takes a bit longer to cool, and that is why you hear noises. But since it is a normal process that does not harm the car, you should not panic.
You might be asking “Why does my car make a humming noise when I turn it off?” The car makes a humming noise when turned off because the cooling system takes some time to cool the engine. It may take a while if you have towed an object or an overheated engine.
Other reasons include a long drive and driving on a hot sunny day. The cooling system might take up to 5 minutes to cool the engine, so you will keep hearing the humming noise.
– Loose Components Produce a Loud Noise
If you hear loud rattling noises from the car as soon as you stop the car, some parts might not be fixed in place. Generally, the noise depends on the size and material of the moving component.
Most of the time, it sounds like a metallic part dangling or rattling. But sometimes, a component moves fast and then bangs into another car part. It might create a diesel engine noise after turning off the ignition.
The parts may get loose with time due to normal wear or other reasons. This situation requires quick repair as it can be harmful in the future.
– Lack of Proper Lubrication
If you have not changed the engine oil in a while, or if the oil levels are low, you might hear a knocking sound. Low oil levels mean that car parts are not lubricated, thus they make noise. Moreover, due to low lubricant, the higher friction creates heat. This heat expands different parts as they are metallic.
So as soon as you turn off the engine, these parts start cooling and coming back to their original size, which is the reason why you hear the noise.
– Buzzing Noise From the Evaporation System
If you are thinking, “Why is my car making a buzzing noise when off?” there can be a problem with the evaporation system. The evaporation system is present in vehicles that run on gas. This system prevents the evaporation of gasoline.
The evaporation system makes a muffled noise or vibrates a little when you stop the engine. It is completely normal and happens in new car models.
– Sound From Headlight
Some modern cars have high-end headlights with different options. These headlights make a loud shrill noise that might end with a clicking sound. Meanwhile, the car keeps the headlights on, which may help you walk in the dark.
This system works with a timer that keeps the light on for a fixed period. But this can only happen if your car has this technology.
How To Fix a Car That Makes Noises When the Engine Is Off?
To fix a car that makes noises when the engine is off, you can try changing the oil. Hire a mechanic to fix the radiator noise, broken gasket, and loose car parts.
Fixing the radiator involves replacing a defective relay or other damaged components.Most repair processes do not cost much except for replacing the gasket.
– Change Oil
Changing the oil can fix the noise of the car. Changing the oil is important even if the car is working fine because it pollutes over time. It reduces its lubricating abilities, and the car starts making noise. You should also check the oil levels to avoid engine overheating.
– Fix the Radiator Noise
Fixing the radiator depends on how it got damaged. For example, if the fan relay is defective, you can replace it. Other repairing techniques include cleaning the radiator and replacing broken components.
– Fix the Head Gasket
A broken or cracked gasket needs replacement. Replacing it with a new one can cost more than $1,000. But now, some chemical repairing techniques can fix a cracked gasket if the damage is not too big.
– Fix Loose Car Parts
If you want to fix the loose car parts back in their position, it is better to hire a mechanic. The time to fix the component depends on the specific part or severity of the problem.
Conclusion
With all the reasons mentioned here, you should have an answer to “Why is my car making noise after engine turned off?”
So before you start diagnosing the major issue, let us have a look at the main findings:
- A noisy radiator and leakage of the gasket are common reasons why a car makes noise when parked.
- Rear cases might occur due to the noise from the evaporation system and headlights.
- Changing the oil or refilling the coolant are the easiest ways to fix a noisy car.
- A mechanic can replace the cracked gasket and connect the loose car parts.
After reading this article, you are perfectly capable of diagnosing the problem. You can also do some repair steps and leave the rest to your mechanic.
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