The car makes a sloshing sound when stopping. What are the causes?

There are various reasons why your car makes a sloshing sound when stopping. Depending on where the noise originates, several diagnoses are possible.

Foremost, air might be trapped in the radiator if the noise originates from the front end of your vehicle. The trapped air causes the coolant to drain rapidly, thus posing a significant risk to your engine. This might indicate a leak in the vehicle’s cooling system or a blown head gasket in the engine, allowing air to get inside the radiator.

Likewise, sloshing can be caused by clogged air conditioner (AC) drain lines after experiencing rainfall. 

The AC drain lines eliminate condensation accumulated in your car’s AC unit, and during heavy rainfall, debris can block the drain lines making them retain water.

Originating from the car’s passenger side, the sound is most apparent during acceleration and deceleration. Other possible causes of the sloshing sound include worn-out AC compressors and low coolant levels in the coolant system.

However, worn-out AC compressors and low coolant levels occur less frequently compared to clogged AC drain lines and air in the radiator. 

How Can I Stop Sloshing?

You can stop your vehicle’s sloshing noise by properly diagnosing its cause. To stop the sloshing sound caused by air in the heating system, check for any leaks in the coolant lines and have them fixed.

If the air in the heating system is due to a blown head gasket, replacing the gasket is mandatory to stop the noise. 

Afterward, you must have the cooling system professionally flushed to eliminate any air in the system. In the case of clogged AC drain lines due to rainfall, you can inspect and clear the lines from debris which will resolve the issue.

However, most cars can easily get rid of the water caused by rainfall. When driving, the water is gradually expelled from the AC drain lines.

Regarding low coolant levels and worn-out AC compressors, topping up the coolant and replacing the worn-out AC compressor should stop the sloshing sound.

It is recommended to have a certified mechanic diagnose the cause of the sloshing sound in your vehicle to ensure proper diagnosis and management of the problem.

How Much Does It Cost to Fix This Problem?

The cost of fixing the sloshing sound depends on the problem’s cause. Foremost, when the coolant is leaking via the head gasket, repairs can total over $1,000.

However, when the leak occurs from the coolant lines or radiator hose, you can expect to pay an average of $100 to $400. Likewise, replacing a worn-out AC compressor can set you back around $800, while purchasing 4liters of high-quality coolant needed to top up the low coolant levels costs about $50. 

In contrast, fixing the sloshing sound from clogged AC drain lines is inexpensive. You can fix this issue from the comfort of your garage.

One do-it-yourself (DIY) way to do this is by attaching a hook to a long thin wire and pulling out the debris from the drain line. Also, you can use compressed air to force out the debris, thus clearing the AC drain lines.

However, when the DIY fixes prove ineffective, book an appointment with your mechanic. 

Is There Any Way To Prevent This Issue In The Future?

Potential leakages in the cooling system can be prevented by regular maintenance, including changing the gasket and seals after the recommended manufacturer’s period.

However, regular maintenance will not prevent all leakages in the coolant lines. Additionally, parking your vehicle in an indoor garage can reduce instances of AC drain lines clogging caused by rainfall.

Moreover, regularly clearing the AC drain lines will eliminate debris and prevent clogging. To prevent sloshing due to low coolant levels, regularly topping the coolant to the recommended levels is advised.

Although the above-listed ways help prevent sloshing sound, they do not permanently solve the problem.

Take Away

It is normal for your vehicle to produce sloshing sounds when starting, accelerating, and stopping. This sound can be due to air in the radiator caused by coolant leaking.

Left unchecked, the coolant can drop to extremely low levels, which will hinder its cooling capabilities resulting in the engine overheating.

Resolving leaks in the coolant system can be pretty expensive, depending on the leak’s location. Another common cause of sloshing sound is water in clogged AC drain lines, which is harmless to your vehicle.

With simple DIY procedures, you can resolve this issue at home. However, experts recommend seeking professional mechanic help when you cannot resolve the issue yourself to prevent potential car damage.

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