Car Rattles When Idle (Why And What To Do About It?)

If you hear that your vehicle is making that rattling noise when idling, it leaves you confused and concerned about why it is ratting. The repair can be simple and will not require you an expensive fix, but on the other hand, it might also require you an expensive repair. And having that unfamiliar sound coming from your vehicle is frustrating to everyone. 

That is why it is essential to know why your vehicle would rattle during idling. With that, we have this article. In this article, you’ll learn all about the reasons why our vehicle rattles and what you can do about it. 

You should notice and note that your engine is not making noise if you are only going for high speed. And you might notice that the ratting will only occur if your vehicle is idling, and then it will again disappear if your vehicle is running. Idling means that your vehicle’s engine is running, but the vehicle is not moving or in motion. 

If you have turned the key on or the button on, the ignition will be switched on—the ignition functions as a generator. A very high voltage from your car’s battery can send the voltage to each spark plug of the voltage. 

This will then ignite the fuel-air mixture in the combustion chamber while using a spark plug to get the engine running. But let us focus on the rattling of a vehicle when idling. Let us start.

Car Rattles When Idle

Why Is My Car Making A Rattling Noise When Stopped?

If your vehicle is idle and will produce a rattling noise, there are a few different things that can go wrong. The very common rattling is from beneath your vehicle. If the rattling noise is under your vehicle, it will tend to be loose. 

This can also mean many different things, so it would be the best choice to lift your vehicle from the ground. If you do not have enough room, you can use a jack and then look for the issue. You can access the engine by propping up the hood. 

If you notice that your vehicle has two hood struts, it will be crucial because they are used simultaneously. An engine is complex, and it must be operated correctly and adequately. 

An engine has many moving parts, and these moving parts have their functions. So for why your vehicle is making a rattling noise when on idle, these are the possible reasons.

1. Motor Oil

If your engine oil level is shallow, it can make an audible rattle that can be heard over loud noise. This is the most common thing you must notice if your engine is rattling. This may sound like extra oil and that it is the solution, but you might need an oil change for that. 

The reason is that the oil is used as a lubricant, and if your engine is not lubricated enough, then it can cause damage to the surface of your vehicle. You can drain the oil at home by using an online guide. 

You can also get a mechanic to do the job for you. If there is an added new oil and the rattling persists, this can mean something else. 

2. Serpentine Belt Tensioner

The serpentine belt tensioner is the thing that is holding the serpentine belt. If it is damaged, then it can cause a rattling sound. The way to repair this is to replace it, and you can do this easily at home. 

However, the replacement can cost you around fifty dollars. So having a mechanic do this can cost you anywhere above one hundred dollars. 

3. Timing Belt Tensioner

The timing belt tensioner keeps the tension on the timing belt. The reason for this is that the timing belt will be exposed to a lot of heat. Over time, they will naturally expand, and they will become looser. 

The function of the tensioner is to counter by increasing the tension whenever they are lacking on it. You can take off the belt by moving the tensioner in the direction so that the belt will loosen. If it is loose enough, you can now then remove the belt. 

You can also turn on the engine to check if there is noise. You may need to replace the tensioner. Removing the belt and running the engine will not charge the battery. 

If you want to replace the belt tensioner, you can visit a mechanic as the issue can be complex. It can cost you an expensive repair. You can also check for others if there are cheaper ones.

What To Do When Your Car Rattles When Idle?

You can get rid of the rattling of the engine noise by bringing your vehicle to a car garage. You can have a professional mechanic check your vehicle and repair the problems you may have with your vehicle if many things are causing your vehicle to rattle if you are idling it. It’s best to have your car checked by an expert.


In summary, many car drivers have been experiencing a rattle on their engine when idling. This is confusing and frustrating to a lot of car drivers. 

This will make them think that there is something wrong with their vehicle. There are plenty of reasons for that. You have to know the specific reason to know how to fix it.

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Image credits – Canva

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more