What causes sloshing water sound in jeep wrangler and how to fix it?

Water sloshing sound in your wrangler is most likely due to liquid-related issues, it could be the coolant in the AC system or clogged water in a particular part of your wrangler. Sloshing water sound in jeep wrangler is not a good sound and should be paid attention immediately to prevent major issues from occurring.

To identify where the sloshing sound is coming from you have to listen carefully when you start your wrangler, when accelerating or when braking. By doing this, you amplify the sloshing sound and you are able to identify specifically where it is coming from.

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A/C-related issues

It is mostly due to a clogged A/C when you hear a sloshing water sound in your wrangler; it is mostly due to a clogged A/C. The sloshing water sound is also heard when accelerating or cornering, the passenger side of your wrangler, water sloshing when starting your wrangler, or from around your wrangler.

You might hear this sound immediately after you drive in the rain or take your jeep off-roading, then end up driving through the water.

Water sloshing when accelerating or when cornering

This is caused by air in the A/C system. If there is air in the A/C system, it goes to the heater core as the highest point in the A/C system. The water pump spins quicker as you accelerate, thus forcing the coolant into the heater core and pushing the air out. This is what causes the sloshing sound.

How to get the air out of the A/C system?

Get the air out of the A/C system, get the engine warm, then let it idle.
Open your hood and secure it with the hood latch. Locate the top radiator hose neck.
Slide a flat-head screwdriver between the top radiator hose and the radiator hose neck.
With the engine idling, all the air will come out until all you see is the coolant coming out. If the coolant starts leaking, retighten the hose clamp.
Test drive your wrangler and listen for any water sloshing sounds.

Water sloshing sound from the passenger side

Your wrangler’s A/C drains are located on the passenger side. Water sloshing sounds from the passenger side is audible even when you bang your doors but become louder when accelerating and braking. When you drive your wrangler in water or in the rain, water accumulates in the A/C ducts instead of draining.

The more the water gets in, the louder the water sloshing sounds. If the drain holes are blocked, water does not drain at all, and if you don’t clear the drain holes, it will lead to more issues.

Failure to unclog the A/C drain lines will lead to water accumulating on the footwell, located on the passenger’s side. You may notice moisture on the mat on the passenger’s side which means that excess water has accumulated and is now leaking into your wrangler. This is an easy fix as all you have to do is clear the clogged A/C drain lines.

How to unclog the A/C drain lines?

Find an inclined parking spot and park with the front wheels higher than the rear wheels. You can use a jack to raise the front wheels.
Cut a thin and strong wire to a length of about one foot or one and a half feet. Hook one end of the wire
Go underneath your wrangler with a flashlight and locate the drain tube. It’s a small rubber hose attached to the engine.
Detach it from the engine so you can access the inside part of the tube. Then insert the hooked end of the wire first into the line.
Pull the wire back and forth the tube until water comes out.
If the water stops coming out of the tube, insert the wire back in the tube and pull it back and forth again to ensure nothing is blocking the water.
Reattach the drain tube to the engine, then perform a test drive and listen for water sloshing sounds.

Water sloshing sound during start-up

This is caused by a faulty heater core. The heater core is responsible for circulating the coolant through the A/C tubes that radiate heat into your wrangler. If the coolant is circulated, it will stay in the tubes. The heater core only needs to be serviced but ensure you check the condition of the tubes if the heater core checks out to be okay.

If the heater core is too faulty, you’ll need to replace it. Replacing a heater core is not an easy task, but you can do it from your home garage if you have the tools and some mechanic experience.

How to replace the heater core on jeep wrangler?

Throughout this process, arrange everything you remove in such a way you’ll be able to reinstall everything back. Put the screws in small labeled boxes or bags that you can identify which screws belong where.

Remove the negative terminal on the battery, then remove the battery. This makes the hoses and the chassis nuts easily accessible. Then drain the antifreeze fluid from your radiator.
Remove the whole steering wheel assembly carefully so as not to trigger the airbag.
Disconnect the wiring harnesses from the inner panel’s left side, which is accessible from the hole where the steering assembly was.
Disconnect the driver’s side defroster hose, which is at the central duct. Twist and pull gently for it to come out. Then remove the glove box.
The void created by removing the glove box removes all wiring harnesses, passenger side defroster hoses, and the bolts underneath the airbag.
Pry off the upper part of the dash, then remove screws from each side of the door pillars and along with the window where the dash is mounted.
Ask for a hand while removing the dash as it needs to be held from both sides. This exposes the firewall to where all the connections lead to.
Discharge the A/C refrigerant, then disconnect the refrigerant lines from the evaporator.
Disconnect the vacuum supply line connector, then remove the L-shaped drain tube that comes from underneath the can.
From the engine bay of your wrangler, remove the HVAC nuts. They are 5 in number, 2 holding the evaporator can, 1 to the bottom of the blower fan, 1 above the engine in the middle, and the last one you have to access by removing the drain tube and the cowl plenum drain.
Remove the floor duct from the cabin by removing the screws that hold it in place.
Remove the HVAC unit from the firewall bracket, then slide the unit slowly towards you. Place it on a workbench where you can start disassembling it.
Separate the upper and lower housing valves, then gently remove the cover of the HVAC unit.
The heater core is now exposed. Remove it, then clean the housing of any antifreeze leftover from the old heater core.
Install the new heater core and tightly close the cover.
Reinstall everything back as it was then, replace the A/C coolant. You can now test drive your wrangler and listen for any water sloshing sounds.

When you underfill the A/C coolant, this could also result in a sloshing sound. By not thoroughly filling the A/C fluid, air bubbles accumulate in the empty space, which causes a sloshing sound. To fully fill you’re A/C with coolant, park your wrangler with the front end higher than the rear. This gets rid of any air with the tubes.

Water sloshing around your wrangler

After raining, water drains through the wrangler’s doors and comes out through the drain holes on the bottom of the doors. If the door drain holes are clogged, the water won’t drain through and remain in the doors. You’ll hear a sloshing sound when driving and when you brake, it becomes instantly loud.

Ignoring this might damage the door’s electricals, such as the lock and the window controls. Mold will also develop because of this, or even worse, rust starts to occur. There might be little water in the doors, but immediately you notice foggy windows, which means there is water in the door.

How to unclog the door drain holes?

Simulate rain by having a running garden hose on top of your wrangler. You can always ask someone to help you.
Lift the seal at the bottom of the door, and if water drains, though, it means the holes are blocked.
Identify all drain holes along with the door and clean both sides of the door seals.
Simulate rain again, then check if there is drainage.

Conclusion

Whatever the cause of the water sloshing sound in your wrangler, you have to fix it before it gets worse. If it’s an A/C-related issue, you might find yourself replacing the whole A/C system, which is not cheap. If water accumulates in the footwell and leaks in, it leads to rusting, and you don’t want rust on the interior part of your wrangler.

Water accumulation in the doors is a common problem that is easy to fix. When ignored can turn into a nightmare for any wrangler owner. Always check your doors for water, especially after heavy rain. Door water drains are easily clogged and relatively easy to unclog.