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Summary
  • Water can come out of your tailpipe due to water condensation during combustion, cat-con operation, and engine heat.
  • In some instances, water on your tailpipe can mean you’re dealing with a bad head gasket and faulty (or worn-out) piston rings.
  • Before going to a mechanic, make sure to check the color of the smoke coming out of your tailpipe, its smell, and the liquid’s consistency. The mechanic will ask you these things.

Water coming out of your tailpipe is not always a cause of concern, but there are times it’s a symptom of a serious problem. That’s why it pays to know when to disregard water running out of the tailpipe and when to take your vehicle to an auto repair shop.

3 Normal Reasons Why Water Runs Out of the Tailpipe

It’s normal for water to run out of the tailpipe due to condensation during combustion, catalytic converter water vapors, and engine heat. Let’s look at each reason in detail:

Water Condensation During Combustion

Combustion naturally produces water vapor, nitrogen, and carbon dioxide. As the exhaust gas moves out of the tailpipe, carbon dioxide mixes with water, causing water to leak from the tailpipe.

This isn’t something to be alarmed about. The leak should stop as soon as your engine warms up. If the water drip doesn’t stop after a few minutes, you might be dealing with a complicated issue.

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Catalytic Converter Operation

modern car catalytic converter in operation
Your catalytic converter reduces the pollutants that your exhaust releases into the environment.

Your catalytic converter reduces the pollutants that your engine produces before entering the atmosphere from the tailpipe. As it turns toxic gas into less harmful emissions, it also creates water molecules. That’s why it’s normal for traces of water vapor to come out of your tailpipe.

There’s nothing wrong with your catalytic converter when this happens, and you can expect the water vapors to stop after a few minutes. Take note that in some situations it might take a bit longer for the water vapors to disappear. That’s because your engine can take longer to warm up in colder temperatures.

Engine Heat

You might notice water droplets coming out of your tailpipe during cold winter months. To operate in the cold, your engine generates a lot of heat. Condensation usually takes place because the temperature outside is low, resulting in water droplets coming out of your tailpipe.

The water droplets coming out of your tailpipe because of engine heat should stop coming out of the tailpipe after a few minutes. Otherwise, it’s time to take a trip to an auto repair shop.

2 Alarming Reasons Why Water Runs Out of the Tailpipe

Although it’s normal to see droplets of water on your tailpipe most of the time, there are some instances when it can mean something is wrong with your engine.

Bad Head Gasket

The head gasket seals your engine’s combustion chambers to avoid compression loss. However, like other engine components, it can fail due to several reasons, like engine overheating.

White smoke could come out of your tailpipe when the head gasket fails. Water droplets in the tailpipe are another symptom. You can read our article on the symptoms of a bad head gasket to learn more about the issue.

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Faulty Pistons and Worn-out Piston Rings

Bad piston and piston rings won’t cause water to come out of your tailpipe on its own. They will if you have a blown head gasket. The moisture can also be due to residual condensation in the engine.

Although water on your tailpipe won’t be an issue, expect to deal with oily residue once your piston and piston rings are bad. These faulty components can cause excessive blow by, which means the combustion gases or pressure is now leaking into the crankcase.

What Does It Mean if Black Water Is Coming Out Of My Tailpipe?

It’s also normal to see black-colored moisture on your tailpipe. The water droplets from condensation might have mixed with carbon deposits.

However, if you notice a lot of carbon residue, a failed component might be causing it. Take your ride to an auto repair shop right away once this happens.

Also, you have to take your ride to a repair shop if there’s excessive water coming out of your tailpipe or you notice black smoke—which can be a sign that your engine is running too rich.

What to Consider Before Going to a Mechanic

If water is coming out of your tailpipe, consider the following factors to determine if you’re dealing with something serious:

Smoke Color

Check if there’s unusual smoke coming out of your tailpipe. Observe its color and thickness. Blue smoke, for example, could mean that oil or other substance is mixed with the fuel inside your engine. It can also indicate a leak.

Smell

Pay attention to unusual smells coming out of your exhaust. For example, a sweet smell can indicate that your coolant is leaking.

See also  White Smoke From the Exhaust: What Does it Mean?

Liquid’s Consistency

If the liquid is too greasy, it might be because it is mixed with oil or unburnt fuel. Take note of these things, and share all your observations with your mechanic.

How Much Will I Spend to Fix the Issue?

It’ll depend on the root cause of the problem. If it’s a blown head gasket, you might need to take your ride to an auto repair shop to have the gasket replaced.

car head gasket replacement process
Head gasket repair or replacement can set you back by $1000 to $2000.

Head gasket repair or replacement can set you back by $1000 to $2000. Although an aftermarket replacement part isn’t that expensive, labor costs can be high due to the complicated nature of the repair. Also, on higher mileage vehicles, you won’t be able to replace the head gasket. You’ll need to have the engine replaced to fix the issue.

On higher mileage vehicles, you won’t be able to replace the head gasket. You’ll need to have the engine replaced to fix the issue.

Anthony Harlin, ASE Certified Master Automobile Technician

On the other hand, if it’s the piston or piston rings that need replacement, you’ll have to know how many pistons need replacement to estimate the exact repair cost. Expect to spend around $2000 on average.

Don’t think twice about taking your ride to a repair shop once you notice anything unusual. It’s better to identify an issue early on than ignore it and spend more on repairs in the future.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Tony Harlin is a Master Gas and Diesel Diagnostic Technician with over 18 years of experience. He works full-time at a large independent automotive shop as a driveability and repair technician working on all types of vehicles with a focus on diesels. ASE certifications include A1-A9, L1 and L2, as well as X1.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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