Updated at: 10-08-2023 - By: Lucas

The interior of your car may make unusual sloshing noises when it rains. If so, you may be asking what it is and how to get rid of it.

Your car’s windshield wiper motor is the most typical cause of water sloshing. Sunroof leaks, damaged seals on windows or door frames, or a shattered windshield can also cause it. Depending on where the sound is coming from, there are a variety of possible causes and solutions.

We’ll talk about how to find the source of the problem and how to resolve it.

What Causes Water Leaks in the Interior of Your Car?

Sloshing Sound In Car

Interior water leaks can be caused by a variety of things, but the most typical ones are as follows:

  • A failing windshield wiper motor
  • A leaky sunroof or roof rack
  • Damaged seals on the windows or door frames
  • Cracked or broken windshields

How Can You Troubleshoot and Fix a Water Leak in Your Car?

There are various actions you may take to troubleshoot and remedy a water leak in your vehicle. Included in these steps are:

  • Checking the windshield wipers for damage or obstruction
  • Inspecting the seals on the windows and door frames for damage or cracks
  • Checking for any leaks under the car and on the underside of the vehicle
  • Visually check your sunroof to make sure it is not leaking

What Causes Water Sloshing From The Passenger Side?

Sloshing Sound In Car-2

There’s a chance the sloshing sound is coming from the back seat. Don’t assume that the water is solely coming from the sunroof because there are drain holes on both sides. Any place with clogged drain holes could be the source of this problem.

This could be due to a variety of factors, including but not limited to:

Blocked drain holes

A gurgling sound may be heard if the drains are plugged. Drain lines can be visually inspected to determine if water is flowing freely. If dirt or debris is clogging the drain lines, they can be easily cleaned out.

Drain holes are very high

Sunroof reservoirs are a common feature on automobiles with subpar engineering. Whenever it rains, this reservoir fills up with water, and the small drain holes can’t handle the volume.

That’s why your car’s exhaust makes a water sloshing noise while you drive. A reservoir on the passenger’s side of the car will hold the water.

Alternatively, if there is a loose connection to the sunroof assembly and water is gathering, you may hear this sound.

The drain holes may be smaller than normal

Perhaps the drainage system was constructed with holes of lesser diameter. In our expertise, we have never seen anything like this from any company.

Water leaking into the passenger cabin

When it rains, water will seep into your car’s cabin if your door seals are missing or the weatherstripping on either side of the door is weakened. Mold in carpets and seats, for example, might arise as a result of this and necessitate remediation.

Worn out sunroof drains

Drain holes can become clogged with debris after many years of regular use. When it rains, this might cause them to become clogged, resulting in this sound. When the weather changes, you may hear if the sunroof has a worn-out rubber gasket around the perimeter.

These gaskets typically need to be replaced every few years because of the hardening effect of sunshine on them. This water sloshing issue can be resolved by purchasing new gaskets to replace the old ones.

You can hear water sloshing from your sunroof when driving in rainy weather if this fault is affecting your sunroof’s drainage system.

What Causes Water Sloshing Sounds During Car Start-up?

Sloshing Sound In Car-3

It’s fairly uncommon to hear water sloshing in the radiator when you start your automobile.

Coolant bubbles are to blame for this. When you start the car, these air bubbles and any other trapped air are pushed to the surface of the fluid. The result is a sloshing noise that may be heard from inside your cabin.

When the engine expels the mixture, it dissipates. This is analogous to giving a soda bottle a good shake before cracking it open. Only in your cabin are air bubbles causing some noise.

The heater core may need to be replaced if you continue to hear this noise even after starting your car and see signs like puddles or water droplets on the ground beneath your vehicle after driving.

To avoid a costly problem in the future, you should see a mechanic right away if that’s the case and have it inspected and repaired quickly.

Before bringing your car into a shop for an examination, take the following steps:

This sloshing sound is usual when the vehicle is just getting started. It is possible that your heater core is malfunctioning if you continue to hear or see symptoms like water droplets under your car after driving.

Sunroof Problems and Quick Repairs

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People who live in hot areas and enjoy keeping their vehicles cool can benefit from a sunroof. It is possible that the seal between the sunroof and the rest of the roof will begin to break down over time.

Every time it rains or you wash your automobile, water will drain into your vehicle if this occurs. Sloshing noises in the car can be caused when water drips down to the drain holes and cannot all be gotten out at once.

You could end up with stained ceilings and interiors if you don’t clear out the drain holes in your car’s headliner quickly enough. Here’s how to figure out whether your sunroof drains are clogged and how to fix the problem.

What you’ll Need: Materials

Expenses Predicted

A scale of difficulty from 1 to 10. (1 being easy and 10 being difficult)

What you’ll Need:

Step 1

Sunroof open and locate the screws that hold your headliner in place. Each side of the window will have a screw. Be careful not to drop these two screws into the car’s interior when using a Phillips head screwdriver to remove them.

Step 2

Pry open the plastic cover you just removed with a flat-head screwdriver by opening it like a clamshell along all of its seams until you can pop it out entirely (see image). By removing this, you’ll have access to your car’s four corners and the area under the headliner (see images).

Step 3

Locate a small drain hole that is at least 4 5 inches in diameter by lowering the headliner (see image). Check all of your sunroof drain holes, even if they aren’t the primary source of water drainage.

Step 4

You’ll need a bucket of hot water, a sponge or towel, and scissors or a sharp knife to clear the sunroof drains of any debris that has accumulated.

Using a pail filled with hot water, dip your towel into the water before squeezing it over the top of the drain holes to remove any remaining soap residue. Do this all the way around the drain openings to check for any possible obstructions that may be buried (see image).

Step 5

If your garden hose isn’t long enough, go out and get one. The blue variety used for window cleaning is the cheapest alternative. In order to get rid of any remaining material, you’ll need to reach down into the hole with your hose and begin rinsing.

If you’ll be using a bucket to rinse the suds rather than a hose, you may want to add some soap or shampoo to the water to help it froth up (see image).

Step 6

You can dry your car’s interior with a towel once you’re sure there’s no debris in the drain hole and then reinstall the clamshell plastic cover by snapping it back into place.

Step 7

If you use some glass cleaner, you should be able to remove any dried-out water stains from the headliner. You can also use a moist towel to clean any places that don’t come clean.

Step 8

Pull down any excess material that hasn’t been cut away from the sides of the window while you’re replacing the headliner cover.

Step 9

Reinstall the two screws you removed previously to secure your headliner in place once you’ve checked that everything surrounding your car’s sunroof opening looks good.

It’s now time for the 10th and final

Step 10

You’ve finished. The only issue that may arise now is if rainwater seeps into your vehicle during a subsequent downpour. Then, you’ll need to discover the leak and fix it quickly before it causes any more harm.

But for the time being, your sunroof drains have been effectively unclogged and restored to full functionality!


Can A Under-filled Cooling System Cause Water Sloshing?

Yes. When you speed or go up a hill, you may notice water sloshing around in your car’s interior because there is not enough coolant to handle the engine’s heat and there is no coolant left over to prevent items from overheating.

People often forget about their radiators until it’s too late, which is a major cause of this problem. Another possibility is that you bought a car that didn’t have enough coolant in it, or that you had an accident where fluid drained from your radiator and went undiscovered.

This means that if you drive or sit in the same position for long periods of time, you may only have enough coolant in the system to keep everything functioning for a short time.

The water sloshing will begin to occur inside your automobile when the coolant level drops over time (if it isn’t monitored). It’s going to become worse till the engine overheats and needs to be replaced once that happens.

Get some coolant added as soon as possible if you hear water sloshing around in your automobile. This will help prevent the problem from getting any worse. Even if the sound is greater when you accelerate or move up a hill, this is especially true (due to lack of coolant).

What Causes The Water Sloshing Sound To Be So Loud?

The amount of noise-canceling material in your car’s interior determines how loud the water sloshing sound is in some vehicles (and how quiet it is in others). As far as noise cancellation goes, some vehicles have none at all, while others have a lot of it.

There is a bigger risk that you will hear the sloshing sound in your automobile if the interior noise reducing material does not perform adequately. As before, if the coolant levels are low and/or the engine has already overheated, this is much more critical.


Even though the sound of water sloshing around inside your automobile is frustrating, you should know that it is fixable. If you pay attention to where you hear the sounds, you can eliminate some of the potential reasons. You can always take it to a local mechanic if you’ve attempted to fix it yourself and haven’t had much luck.