Grinding Noise When Turning Engine Off! 4 Major Reasons?

Why Does Your Car Make Grinding Noise When Turning Engine Off? Detailed Reasons With Solutions

As I mentioned earlier, there are four main reasons behind the grinding noise when the engine turns off. Let me explain the reasons mentioned above and guide you on how to identify these problems.

1. Routine Contraction of Metal Parts

The engine in your car consists of many metal parts. Most of the engine components are exposed to extreme temperatures while driving the vehicle. The heat causes these engine components to expand from their original size.

When you stop the vehicle, the engine output already becomes low. As the heat reduces, metal components start getting back to their normal size. Especially when you turn the engine off, the contraction process happens faster. So, you might hear grinding noises between metal parts.

How to Fix This Problem?

1. There is nothing to worry about if you hear a grinding noise between metal parts that aren’t directly a part of the engine block.
2. If you can’t identify this, you can take the vehicle to an experienced mechanic who can identify where the sound is coming from. When the sound is caused by heated metal parts, you don’t need to fix anything.

2. Airflow In the Cooling System:

The cooling system of your vehicle carries liquid coolant through different channels. If there is a leak in the system, air can penetrate the cooling channel. When you turn the engine off and the coolant travels back to the reservoir, the airflow inside the cooling system will cause noise.

It can sometimes be a “swooshing” noise or a high-pitched grinding noise if the airflow is stronger. Another reason behind this problem is a blown head gasket.

The head gasket keeps foreign bodies from contaminating the liquid coolant. But if the gasket is blown, you will hear loud grinding noises from the engine while turning it off. The grinding noise can also be present while driving the car.

How to Fix This Problem?

1. Testing the coolant line or head gasket requires special skills. So, you shouldn’t do it yourself as a normal user.
2. Take the vehicle to an auto repair shop and get the coolant system checked for leaks. Fixing the leaks might cost about $100-200, including parts and labor. After fixing the leaks, you should refill the coolant reservoir. The top level of the coolant should be near the MAX marking on the dipstick.
3. If the head gasket is blown, the replacement cost will be heavy on you. It might cost anywhere between $1,000 and $2,000, including parts and labor. The price can vary depending on your car model.

3. Poor Assembly of Engine Components

The engine block is mounted to the chassis using mounting bolts. Other major components are also assembled using bolts, belts, etc. Over time, these accessories can wear due to excessive heat in the engine bay.

As a result, some components will become loose and start grinding with other components. Loose belts or bolts cause the engine components to vibrate vigorously when the engine is on.

But when you are turning the engine off, that vibration stops as well. And before everything goes silent, you will hear one last grinding noise from the engine.

How to Fix This Problem?

1. If the grinding noise is a short-term noise, you can be sure that it is coming from a loose component. However, finding the exact component might require extensive knowledge of engine components.
2. So, it is better to take the vehicle to a repair shop. Get the necessary accessories replaced if they are worn. And make sure all components are fitted tightly to avoid vibration. Learn more about engine assembly process quality improvement.

4. Low Coolant or Oil Level

Engine oil flows through the channels around the engine block and keeps the components lubricated. It ensures the components work smoothly without any noise. But when the engine oil level is low, these components start grinding together.

So, you will get that grinding noise when turning the engine off. Coolant also flows around components to keep them cool. When the coolant level drops due to leaks, as I already discussed before, or lack of routine checking, parts become hotter than they should be. And it causes the grinding noise from the engine when turning it off.

How to Fix This Problem?

1. The first thing you should check is the engine oil. Remove the oil reservoir cap and pull the dipstick out.
2. If the oil mark is near the tip of the dipstick, it means the engine oil level is too low. Refill the engine oil promptly to keep the engine components lubricated.
3. Do the same thing for the coolant reservoir. If the coolant level is too low, refill that too.

FAQs

Check answers to some frequently asked questions about noises when turning the engine off.

Q: Why does my car make a fan noise when I turn it off?

The fan noise is normal because the cooling system tries to cool down the engine. So, the fans may be turned on for a few seconds or minutes after you turn the engine off.

Q: What causes the turbo noise when turning the engine off?

When you turn the engine off, the airflow gets off the compressor. As a result, a weird fluttering noise may come from the engine.

Q: Can dirty oil cause grinding noise?

Of course. Dirtiness of the oil reduces its lubrication properties. So, the engine components will start grinding together when the oil is dirty.

Final Words

I understand how annoying that grinding noise when turning the engine off can be. In most cases, the reason behind this grinding noise isn’t that serious. Still, you shouldn’t ignore the noise.

Make sure you check all the reasons I mentioned above. If you aren’t experienced enough to perform the checks, call for professional help. If the fixes are performed properly, the grinding noise when turning the engine off should go away.