Water Sloshing Sound In Car – Causes & Solutions

Are you hearing water sloshing sound in car, either from the exterior or interior? If yes, what could be the causes, and how to address the issue? If you hear this sound, you already know how annoying and distracting it can be. Aside from that, it can also be a pointer to more significant issues in your car.

In this article, I’ll outline the possible causes of the water sloshing sound in back of car and any other areas of the car. You’ll also learn how to fix the problem and the consequences of driving with water sloshing sound in a vehicle. Grab a seat and a cup of coffee while I uncover all you need to know.

water sloshing sound in car

What causes water sloshing sound in the car?

Water sloshing noise in a car typically occurs due to a failure of one or two car components like low engine coolant, faulty evaporator, defective heater core, blown head gasket, blocked windshield drain, or clogged door drain.

Let’s look at these possible causes in-depth to better understand how they can be the root cause of the sloshing noise.

Low engine coolant

Low engine coolant is the most common cause of water sloshing noise in a car. The noise will be present while idling the vehicle and more obvious as you accelerate the car.

When using heat in your car, hot coolant from the engine travels to the heater core, and a motor fan blows the heat from the hot coolant into the cabin to provide the required heat. If the engine coolant is low, it’ll cause a sloshing sound as the heater core fan blows through it.

Blown head gasket

The head gasket is the gasket between the head cylinder and the engine block. The purpose of this gasket is to prevent water and oil from mixing. Water and oil have different passages. If the head gasket gets burnt, it’ll cause internal oil and coolant leaks. It can also cause combustion gases to escape from the combustion chamber. This situation will cause water in engine sound.

Water in the Evaporator drain

Why do I hear liquid sloshing in my car when I start? The cause is not far-fetched from the water in the evaporator drain. When you turn on the AC in your ride, condensation happens on the evaporator coil and other air conditioning system components.

The condensation drips into a drain pan and later exits the car. If the drain pan becomes clogged, the water will accumulate in the pan, resulting in a sloshing sound as you drive. A common indicator where you have water in the evaporator drain is if the sloshing sound increases when braking or taking sharp turns.

Clogged windshield drain

Another possible cause of a sloshing sound in your car is a clogged windshield at the cowl area. If there’s too much water buildup here, it’ll cause a sloshing sound, leak into the interior, and corrode the floorpan.

Clogged door drain

Under perfect conditions, water can enter your car while washing or when it’s raining. However, there’s a drain hole where the water flows out. If the drain hole becomes clogged due to dirt, junk, or other particles, the water will accumulate in the hole instead of flowing out. This will cause a water-sloshing sound.

Trapped air in the cooling system

Another potential cause of the water sloshing sound in a car is trapped air in the cooling system, especially in the heater core. Air can get trapped in the heater core even though you have enough coolant in the radiator. Inspect the cooling system for trapped air if you hear a water sloshing sound in dash. It could be there’s air in the system.

While there may be other possible causes of water sloshing in a car, these are the most common causes you should look out for when you hear a sloshing sound.

How do you fix the sloshing sound in your car?

Since there are several causes of sloshing sound in a car, there are also several ways of addressing the issue. All you need to do is determine when and listen to where the noise is coming from and diagnose the individual parts in that area. For instance, when accelerating a car, the water sloshing sound differs from water sound when turning car off. Similarly, the sloshing sound in the front is different from the one in the back.

Remove & resolve air in the cooling system.

Inspect the cooling system and fix any area allowing air into it. Ensure the up and down radiator hoses are adequately tightened. Also, check the radiator cap and replace it if it is faulty. A lousy radiator cap can allow air to get trapped in the system.

Add engine coolant

If the water sloshing noise is due to low coolant, the only feasible solution is to top up the engine coolant. In any case, if you notice the coolant is reducing pretty fast, there’s a leak somewhere in the system that needs to be addressed. It could be an internal or external leak. Check the cooling system components for leaks and rectify them. If the coolant is not leaking externally, you could have a blown head gasket.

Unclog the door drain.

Check the door drain and see if there’s any blockage. If the drainage is blocked, you can unclog it by fitting in a wire that can enter the hole or by blowing out the blockages with compressed air.

Unclog windshield drain

If you suspect the water sloshing noise is coming from the windshield drain, thoroughly inspecting and cleaning that area could be all you need to fix the problem.

Unclog evaporator drain

The only way to fix water sloshing noise as a result of a clogged evaporator drain is to clear it out. To do this, get compressed air and face it toward the clogged evaporator drain. Blow the air through the drain to clear out the blockages. You can also remove the blockages by using a wire that will fit into the drain.

What will happen if you drive your car with water sloshing sound?

Since there are several causes of water sloshing in a car, the consequences of driving with water-sloshing sounds widely vary, depending on the root cause of the problem. The consequences can be a minor mold growth or severe engine overheating.

Simply put, driving with water sloshing will lead to corrosion, mold growth, increased humidity inside the cabin, and reduced cooling performance, and it can cause catastrophic engine overheating, which could lead to severe engine problems.

Final Words

While the water sloshing sound in car can be distracting and annoying, it’s important to note that it can be a minor issue that you can fix without consulting a mechanic. A low-engine coolant could be the culprit, and all you need to address the problem is to top up the coolant.

Plus, you can tell what’s causing the sloshing sound by paying close attention to where it is coming from. However, if you don’t trust your gut or you are not a DIYer, contact your local mechanic to have a closer look and address the problem.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

Recent Posts