Why is Water Coming Out of My Exhaust While Idling? | What You Need to Know

Your vehicle’s exhaust pushes out gases and particles from the cylinders from within. Any malfunction or irregular change in it, such as excessive water coming out, is a clear sign that something in the vehicle is not right. 

Although condensation is normal, frequent and excessive amounts of water indicate something is wrong. This could be caused by any number of issues, from damaged pistons to something very serious like a blown gasket.

We have collected and explained the most common reasons for this and why it happens. Continue reading to learn more and the water coming from your exhaust, what it means for you and whether you need to book an appointment with your mechanic.

Is Water in My Exhaust While Idling Bad?

Some water from your exhaust while idling is generally not a cause for concern. Water vapour is a normal part of your vehicle’s emissions, and condensation will turn it into liquid water. If water comes out in large amounts alongside another issue, it’s time to book a professional maintenance check.

Why is Water Coming Out of My Exhaust While Idling?

There are several reasons why water is coming out of your exhaust, some are normal, but most are bad. Before you panic and bring your car to the mechanic, we’ve listed the most common causes below for you:

1. Coolant Leaks

Coolant leaks refer to broad symptoms caused by something much more specific. Given the combusting nature of a vehicle, heat is constantly generated and would have to be cooled down to ensure the car can operate as intended without catching fire or causing components to warp or burn. 

If you suspect or have identified liquid from your exhaust to be coolant, it could be caused by any number of failing components, such as blown head gaskets, a cracked EGR cooler or a damaged water pump, just to name a few. If you suspect any of these are causing the excess fluids coming from your exhaust, consult your mechanic as soon as possible.

2. Engine Overheating

Most heat in the engine is generated when the vehicle is started. The oil inside the engine, which is responsible for cooling, will take some time to flow and lubricate the heating components. This causes water vapour to build up within the exhaust if the outside temperature is cold enough, causing water droplets to show up and leave the tailpipe for a few minutes until the oil cools the engine down so that it stops. 

If water continues to flow from the tailpipe even after a few minutes or after you’ve driven around, then your engine could not have cooled down enough, properly, or at all, and may need to be checked.

3. Blown Gaskets

A blown gasket is one of the more alarming causes of water leaking out of the exhaust. Blown gaskets are usually indicated by white smoke coming from the exhaust pipe. The head gasket is responsible for keeping the engine’s combustion chamber sealed, allowing it to build enough compression to maintain engine power and keep the coolant or oil from leaking outside. 

A blown gasket will prevent oil from properly lubricating the engine, causing a constant state of engine overheating and, consequently, water vapour condensing and flowing out of the exhaust pipe. Blown gaskets are not common and are generally caused by ageing engines or extreme wear. However, they are very dangerous as they can cause the engine to catch fire.

4. A Blocked Exhaust

Most people don’t realise that a blocked exhaust system can cause water to come out of the exhaust pipe. Debris and buildup of rust are the most common culprits of blockage and can negatively impact the vehicle’s overall performance. 

If you suspect a blocked exhaust system to be the cause, head to your mechanic for a thorough inspection. An experienced mechanic can clean out the exhaust system without any trouble. However, in extreme cases, the catalytic converter or muffler may have to be replaced.

5. Worn or Damaged Pistons

Worn or damaged pistons and piston rings will not normally cause water to leak from the exhaust pipe while idling unless another problem, such as blown gaskets or residual condensation, accompanies it. These worn pistons will cause excessive blow-by. 

Blow-by is the natural buildup of pressure within the crankcase from air, fuel, and oil going past the piston rings. Excessive amounts of this will create a ‘sooty’ exhaust, oily residue around the exhaust pipe and blue smoke to be released.

Many things could cause excessive wear and damage to the pistons, one of the most common being the use of low-quality fuel, which often leads to cracked pistons. Another more unusual cause is the failure of the exhaust gas recirculation system. This damage can cause oil to find its way into the combustion chamber, which is a major cause of concern. 

6. Catalytic Converter Condensation

Among the less commonly known car components is the catalytic converter. This component reduces the amount of toxic fumes emitted by the exhaust system. This keeps vehicular emissions safe for the environment and nearby people and complies with safety standards. 

During the conversion process, small traces of water vapour are produced, causing water droplets to fall out of the exhaust pipe. This is completely normal and should go away on its own.

7. Issues With the EGR Cooler

In some newer vehicle engines, particularly diesel vehicles, an Exhaust Gas Recirculation (EGR) cooler cools down the exhaust fumes before they enter the intake. A coolant cools these gases, but thermal stress can cause the EGR coolers to crack or warp due to the repeated cycling of extreme temperatures, reaching up to 800 degrees Celsius. 

When this component cracks, coolant can run down into the exhaust pipe and drip. If the dripping liquid from your exhaust pipe smells sweet, it is likely coolant from the EGR cooler.

8. Damage or Issues With the Water Pump

A vehicle’s water pump circulates coolant throughout the system. When the seals inside this component are damaged or start to fail, you will notice a leak originating from the weep hose. This causes coolant to pass and go straight to the hose and eventually down into the exhaust pipe. 

The coolant is usually mistaken as water but can come in varying colours, such as green, orange, or red. A failed water pump is highly likely to cause an engine failure due to overheating, so this should be checked as soon as possible.

9. A Crack in the Engine Block

Issues concerning the engine and its components are never a good thing. Another side effect of overheating is a cracked engine block. This overheating is usually caused by another underlying problem within the vehicle that has not been resolved. A cracked engine block will allow liquid coolant to flow into the combustion chamber, consequently venting through and out of the exhaust system.

Is an Exhaust Leak Expensive to Repair?

Exhaust leak repairs can cost as little as $150 for minor damage but can run you as much as $1,150 for more complex repairs, not including the cost of any part that may need to be replaced.

An exhaust leak may be caused by several reasons, and in some cases, even multiple of them at any given time. Since many components can indirectly cause leaks into the exhaust, an extensive and thorough repair would also likely cost you much. 

Is a Leaking Exhaust Covered by Car Insurance?

Liquid coolant leaks are generally covered by insurance, and even your warranty, depending on the vehicle’s warranty and the particular insurance cover you have. The only reason that insurance might not cover this is if the leak was caused by faulty or wrong DIY repairs or modifications to your car.

Can I Fix a Leaking Exhaust System Myself?

While it is possible for people with sufficient knowledge and experience with cars and their exhaust systems, repair works like fixing a leaking exhaust system are usually best left to the professionals due to the possible complexity of repairs and the potential need for new parts

Unless you are absolutely sure how to go about the repairs, for example, if you work full time as a mechanic yourself, do not attempt to do these by yourself, especially without the guidance of a mechanic, as there is a chance that you may worsen or complicate the damage.

How Do I Get Water Out of My Car Exhaust?

Normally, water from the car’s exhaust does not pose any real concern and will go away on its own. However, if you believe there is a leak within the exhaust system, it’s best to visit a mechanic, as they will be able to identify the proper way of removing the water and repairing any damage done.

What Should I Do if Water is Coming Out of My Exhaust While Idling?

The first thing you should do when water comes out of your exhaust is to observe if it persists. Most of the time, this is simply condensation and does not warrant any action. It is only when the problem is persistent that a visit to the mechanic is required. 

Remember that this does not always indicate a serious problem and could be a simple repair. Do not attempt to repair this yourself, as you risk further damaging the exhaust system.

Related Questions

How Hot Do Car Exhausts Get?

Car exhaust pipes can generally reach anywhere from around 200 degrees Celsius to as high as 260 degrees Celsius. However, the exhaust pipes of faster or performance-oriented vehicles can range from 420 to 540 degrees Celsius. Circumstances such as speed and the outside temperature can affect this.

Will a Car Still Run with a Blown Gasket?

A car can still run with a blown gasket, but it’s incredibly dangerous. A blown gasket can cause a leak that would cause the loss of compression within the engine, which leads to knocking and stalling even at idle. 

James Mitchell

Hi, I’m Jimmy Mitchell and I love exploring this great country with my wife and two boys. I have a 2015 Sterling LX that is the Mitchell Family camping machine. Lets Getaway is the website where I share things about my trailer as I learn them, and help other camper owners to enjoy their RV even more.

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