Knocking Sound After Turning Engine Off (Causes & Fix) - Fixthatnoise (2023)

You don’t have to be told how important and delicate the vehicle engine is as a vehicle owner. Also, every vehicle owner knows that issues with the engine are crucial, the cost of fixing the issues, and the possibility of buying a new engine.

No vehicle owner is ready to experience any hassle with the engine of the vehicle. This is why many vehicle owners are disturbed when they hear knocking sounds after turning off the engine.

Due to how critical the engine is, guessing the likely causes of the issue could be a problem, especially when you are not an expert and a newbie owner. This article is centered on the possible causes of the knocking sound when you turn off the engine and the solution to the issue. Keep reading for more information.


Knocking Sound After Turning Engine Off (causes and possible fix)

You will likely get panicked when you hear a knocking sound after turning the engine off. Well, going to a professional is the right call but you could spend more money when you do not have any idea about the likely causes of the issues and the possible solution. Below are some of the causes and what you can do to fix them.

1. Exhaust system

Most of the vehicles that move on the road are from different manufacturers and they are different models. The model of the engine also differs.

You could be experiencing this knocking sound issue after turning off the engine, especially after long hours of driving, when the engine is turbo powered.

The knocking sound simply means that the engine is contracting after several hours on the road. While this is normal, below are the likely things that could be done to fix the problem.

Give it time

If you use the vehicle for a long trip, all the parts of the vehicle bear the pressure. The exhaust pipe will likely cause a knocking sound when you turn off the engine but you can avoid the noise.

All you need to do is to allow the vehicle to run for a few minutes when you get to your destination before you turn off the engine. It is unlikely that you hear the sound when you do this.

See an expert

Remember that you will only hear the knocking sound when you have been on the road for a longer duration. In a situation where you hear the noise when you turn off the engine and you have not moved for a longer distance, it is recommended that you see an expert for a proper diagnosis of the vehicle.

2. Weather

You might be wondering how the weather causes the knocking sound. Well, during winter or cold weather, the environment will be cold but when you turn on the vehicle, heat will be generated.

This heat from the engine and other sources will expand some parts of the vehicle, especially the metal parts. When you turn off the vehicle, such expanded parts will contrast again and this could lead to the knocking sound. Below are the things you can do to avoid the issue.

Avoid sudden turn-off

Normally, the expanded parts of the vehicle get contrasted when they become cold again after you have turned off the vehicle but you can slow down the process. You can allow the vehicle to run for a few minutes when you get to your destination before you turn off the vehicle.

Go to an expert

The incessant expansion and contraction of some parts of the vehicle due to temperature changes could cause easy wear and loose ends. If the issue becomes persistent, especially when the weather is no longer cold, you should see an expert.

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3. Reduced pressure

There are specifications and recommendations for different parts of the vehicle. When you fail to comply with the recommendations, you are potentially subjecting the vehicle to risk.

For instance, the level and the type of engine oil in the vehicle are important. Maintaining the recommended level implies that the pressure will be adequate for the effective operation of the engine.

In a situation where the oil is below the recommended level, the oil pressure reduces. If you suddenly turn off the vehicle in this instance, you will likely hear a knocking/hissing sound. Below is what you can do to resolve the issue.

Check the oil level

The knocking noise will continue anytime you turn off the engine until you check the oil level and do the right thing. Also, you should not forget that you must use only recommended oil for your vehicle. You can check the manual of your vehicle for the specification of oil that should be used for your vehicle.

4. Position of the cooling fan

The cooling fan is part of the cooling system but could cause a knocking noise when you turn off the engine. This could happen when the cooling fan is out of position due to wear, loosed end, and lack of maintenance.

In this instance, when you turn off the engine, the cooling fan could shake and hit something in the process. The result of that is the knocking sound. Here are a few steps you can follow to resolve the issue.

Check the fan

You should inspect the fan to know its current position once you hear the noise. However, it is recommended that you allow the engine to cool down before you open the bonnet to avoid harming yourself. If the fan is loosed or damaged, you should take the next line of action.

Go to an expert

You don’t have any business trying to tighten the cooling system fan when you do not have the right tool and experience to do it. It is recommended that you go to an expert for proper resolution of the issue.

However, there are instances where the fan would have been damaged while hitting another object, it is recommended that you get a quality replacement immediately.

5. Damaged head gasket

At this stage, many vehicle owners will be apprehensive because they don’t want any issues with the engine. Well, the head gasket could also be responsible for the knocking sound when you turn off the engine.

In most cases when the head gasket is worn or damaged, the cooling system will be exposed to contaminants. This could then cause the vehicle to make a knocking noise while driving and when you turn it off. Highlighted below are some of the things you can do to fix the problem.

Proper inspection of the vehicle

If the head gasket is responsible for the knocking sound, you have to do a proper inspection of the vehicle. Doing this will tell you the current state of other parts of the vehicle.

Replace the damaged part

For a permanent resolution of the issue, it is recommended that you replace the head gasket. Nevertheless, if you discover that any part of the vehicle has also become degraded when you inspect the vehicle, if possible, you should replace the affected parts.

Signs of a failing engine

Irrespective of the state of other parts of the vehicle, the engine must be in good condition always. When it fails, other parts of the vehicle will likely not function. This makes it one of the things that vehicle owners fear the most. Here are a few signs that will tell you when you should pay attention to the engine.

Warning light from the dashboard

The dashboard is one of the quickest places for you to know if there is an issue with the engine. There will be a warning light that will instruct you to check the engine. Moreover, when there is a frequent warning about the temperature of the vehicle, you should consider checking the engine also.

The exhaust smoke

While everybody is trying to protect the environment with the use of vehicles with cleaner emissions, the smoke from the exhaust is still one of the signs of a failing engine. Though smoke from the exhaust is associated with different issues, you should see an expert whenever you notice a change in the smoke pattern of your vehicle.

Fuel economy

When the engine is bad, there will be added pressure on it, which will lead to an increase in fuel consumption. A lot of factors could cause the increase but if you notice the engine warning light on the dashboard and you have been spending more money on fuel, you should see an expert.

Traces of oil

There shouldn’t be any traces of oil on the ground when you park your vehicle and you are sure there is no leakage. When you notice traces of oil, it could be a sign of a failing gasket. Over time, the engine will lack enough oil and that could lead to failure.


Nobody wants issues with the engine but you cannot deny the fact that it could happen. The knocking sound and other issues highlighted in this article could suggest that the engine is failing. Before it becomes complicated, it is recommended that you see an expert.

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