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Why Is My Car Leaking Water & How to Diagnose the Leak?

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Noticed your car leaking water?
Well, it might just be your AC sweating or your car blowing off steam from the exhaust pipe.

Water leaks are usually harmless. But if you frequently notice large puddles of water or other signs like white smoke, you may need expert help. 

Let’s explore the common causes of these water leaks, other car fluids that can drip out, and if you need to worry about them. We’ll also discuss a few possible solutions to fix the water leak.

This Article Contains:

3 Ways to Determine Your Car Is Leaking Water and Its Causes

Here are some potential ways to verify a water leak and its root cause:  

1. Perform a Paper Test

Place a piece of paper or a paper towel under the leak. If the dripping fluid is colorless and odorless, it’s water. 

Note: Another colorless fluid that may leak from under your car is brake fluid. However, it has a thicker consistency and a distinct fishy odor that’s hard to miss. 

2. Look for a Large Puddle of Water and White Smoke

White smoke and excess water dripping from the tailpipe can indicate a blown head gasket

A head gasket typically seals the engine’s combustion chamber, preventing a coolant and oil leak

When the gasket fails, the engine coolant may enter and burn inside the combustion chamber, releasing white smoke. As this smoke passes through the exhaust pipe, it condenses, creating water droplets that drip out. 

3. Identify the Leak’s Location

The location of the water leak can help identify the root cause. Here’s how:

But what if the leak isn’t water?
Let’s check out other fluids your car might leak and how to identify them.  

How to Identify the Leaking Fluid Based on Color

Your car has around 6-8 fluids that help different systems function smoothly.  

Here’s how you can identify these fluids from their color:

  1. Colorless: Water or brake fluid
  2. Dark brown: Older engine oil or brake fluid 
  3. Light brown: Newer engine oil or gear lubricant
  4. Orange: Transmission fluid or engine coolant (radiator coolant)
  5. Red or pink: Transmission or power steering fluid
  6. Green or blue: Antifreeze or windshield wiper fluid 

Tip: If you can’t tell the color easily, place a white cardboard or paper towel under the leak to observe the liquid.

Now that you can identify the leak based on its color, keep reading to find out if it’s a cause for concern.

Should I Worry If My Car Is Leaking Water?

A leak can be harmless or concerning, depending on the fluid:

A. When It’s Water

Generally, water leaks aren’t a cause of concern

If the water leakage is caused by the car’s air conditioning system or exhaust condensation, it won’t impact your vehicle’s performance.

However, if you often notice large water puddles in the back or front of your vehicle, you should call a car maintenance service ASAP.   

B. When It’s Not Water

A colored fluid leak can indicate a wide range of issues, which, if ignored, can further damage your vehicle.

For example:

These leaks could also indicate issues with other critical parts, such as the heater core, water pump, radiator, and power steering pump. That’s why it’s essential to have a professional auto mechanic look at your vehicle.  

But what if there’s water leaking inside the cabin? 
How does that happen?

Let’s have a look.

Why Is Water Leaking Inside Your Car?

Some common causes water may leak in your cabin are:

1. Failing Door or Window Seal

Water ingress (when water enters your car) during rains can mean you have damaged weatherstripping. 

Weatherstripping is the black rubber material that lines your car’s windows, windshield, and doors. It helps prevent rain and wind from entering while you’re driving.

Why you shouldn’t ignore it?
When excess rainwater pools inside your cabin, it could cause water damage, including mold growth. And if the leak comes through the windshield, it can damage the dashboard or trunk.  

2. Damaged Sunroof Seals or Drain Tubes

Your car’s sunroof has rubber seals to keep water and dust from entering the cabin. When sunlight and extreme temperatures damage these seals, water can trickle inside during rain.

Sunroofs also have a drain tube to drain rainwater. But over time, leaves, dirt, and grime clog these tubes, preventing the water from flowing out. Eventually, you’ll notice water ingress.

3. Clogged AC Evaporator Core or Drain Tube

Usually, drain tubes carry the condensed water from the evaporator core and release it outside the car. However, dirt, leaves, as well as road debris can clog the drain tube and block the evaporator core. 

When the condensed water accumulates inside, it can drip out from the sides of the dashboard.

4. Leaking Heater Core

Besides water, a leaking heater core can allow radiator coolant to trickle into the cabin. 

The heater core uses hot coolant to warm air and heat the cabin. But the core can rust or get damaged over time, developing leaks. Once it leaks, you’ll notice a small puddle of coolant pooling inside your cabin.

Note: Coolant has a sweet, syrupy smell. If you notice this odor inside your car, it indicates a coolant leak.

So, how can you repair the leak?
Read on to find out. 

How to Fix a Water Leak in Your Car?

Before we get into the details, remember, that the repair requires working around toxic fluids like coolant and refrigerant in the engine compartment. You’ll also have to handle complex heating and cooling system components, which can be challenging without technical know-how. 

So, for your peace of mind and safety, it’s best to call a professional car maintenance service

Your mechanic will perform these basic steps to fix the water leak: 

  1. Clean the clogged evaporator drain: They’ll use a thin wire to clean the evaporator’s drain tube to remove the accumulated dirt or debris.
  1. Inspect the windshield washer reservoir: They’ll inspect the windshield fluid reservoir for cracks and replace it if it has a crack or a hole. Then, they’ll refill it with fresh windshield washer fluid. 
  1. Clear the sunroof and doors’ drain tubes: The mechanic will use a wire to remove the dirt or debris collected in the drain tubes near the sunroof and door’s bottom edge.  
  1. Replace worn weatherstripping: If the rubber seals around your door, window, and sunroof are cracked, they’ll replace them with new ones.

Note: If the water leak is due to a broken heater core or blown head gasket, simple fixes won’t remedy the problem. Instead, your mechanic will have to perform a complete replacement. 

Keep Water Leak Issues at Bay with AutoNation Mobile Service

Water leaking from your car isn’t a big problem. But if you notice the puddles often, it’s best not to ignore them.

Not sure what type of leak you have?
Then, call AutoNation Mobile Service mechanics to inspect your car’s air conditioning system, door rubber seals, and sunroof for leaks. 

We’re a mobile auto repair solution that offers easy online bookings and upfront pricing. We also offer a 12-month | 12,000-mile warranty on all services, including an oil change and a water pump repair.  

Contact us to address a water, transmission fluid, or oil leak right from your driveway.