Water Coming Out of the Exhaust — What Does It Mean?

Water Coming Out of the Exhaust — What Does It Mean?

There are certain things that your car can do that are clearly bad, like refusing to start or bursting into flames. However, there are other things that can happen with it that aren’t as clear-cut.

Water coming out of your exhaust pipes falls into the latter category. It’s definitely not as concerning as flames shooting out from underneath the hood, but it just seems wrong, doesn’t it?

There are several reasons why you might see water dripping out of your exhaust, many of which are quite normal. We’ll look at all of them in more detail below.

Why Is There Water Coming Out of My Exhaust?

Just because there’s water coming out of your tailpipe, it doesn’t mean it’s time to panic. There are several perfectly normal reasons why this could be happening.

Reasons NOT to Worry About Water in Your Exhaust

1. It’s Just Condensation

Water (in gaseous form) and carbon dioxide are natural by-products of the internal combustion process. Once you turn the engine off and it’s had a few minutes to cool, all that built-up water and carbon dioxide needs someplace to go — and out the tailpipe is as good a place as any.

It’s unlikely you’ll see the carbon dioxide unless you have really strong glasses, but the water vapor will form droplets on the tailpipe, and from there, they’ll drip down.

This is completely normal and nothing to worry about. There’s nothing wrong with your car, and there’s no need to rush over to your mechanic.

2. It’s Just a Different Type of Condensation

While water vapor is created during your engine’s normal operation, that’s not the only way condensation can form on the tailpipe. It could just be moisture from the environment.

This is especially true in cold or wet climates. As your car warms up after you first start it, the heat produced in the engine will create condensation in the exhaust system. As this heat collides with the cold or wet air, it creates water droplets, which are then expelled through the tailpipe.

On extremely cold or wet days, you should let your car idle for a few minutes until the water stops dripping out of the exhaust pipe (this also gives the cabin time to warm up).

3. It’s a By-Product of Your Catalytic Converter

Your catalytic converter helps reduce your car’s emissions by turning most of the noxious fumes into less-damaging gases. These less-harmful gases include water vapor, which can then pool and run out from your exhaust system.

If the water coming out of your tailpipe is due to your catalytic converter, then there’s nothing to worry about. In fact, it’s a good thing — it means your catalytic converter is working properly.

Reasons to Worry About Water in Your Exhaust

Then again, there are also a few reasons why you should worry. Let’s take an in-depth look at a few scenarios.

1. You Have a Blown Head Gasket

The head gasket prevents coolant from escaping your engine; if it gets blown, coolant can either fall out of the engine entirely or drip into your combustion chamber. This is not good, and driving just a few miles with a blown head gasket can do serious damage to your car.

You’ll be able to tell if a blown head gasket is the possible cause of the water in your exhaust because it will be accompanied by white smoke. However, this is a relatively minor indicator of the problem; you’re much more likely to notice your engine overheating, engine failure, or air bubbles in your coolant reservoir.

Expected Repair Cost:

Having a blown head gasket is a serious problem, and repairing it is going to cost you — anywhere from $1,000 to $2,000, on average. However, you can’t put it off. If it’s not fixed in time, it can damage your ignition system, your exhaust system, the fuel injection system, and it could even force you to replace the entire engine.

Pro-tip: Before you descend into complete panic, consider the suitability of a head gasket sealer — these can provide a permanent fix for just a fraction of the price.

2. Your Pistons Aren’t Firing Properly

A bad piston or damaged rings could allow water into the engine, which would then be expelled through the exhaust. The water won’t be the most obvious sign of the problem, though, as you’ll likely notice the fact that your car is producing a lot more smoke than normal first.

That smoke may also be blue and sooty, and there may be an oily residue around the tailpipe. You might also start smelling a burning or sweet odor in the cabin while you drive. None of these things are good, and they’re all signs that you should get your car looked at by a professional right away.

Expected Repair Cost:

This is another expensive repair, and you should expect to shell out between $1,500 and $2,500 to get it fixed. Not to pile on, but bad pistons or piston rings usually won’t cause water in the exhaust unless the head gaskets are also blown. This could end up being quite an expensive repair indeed.

Knowing When to Worry About Water in the Exhaust

At this point, you may be questioning the value of noticing the water in your exhaust in the first place. After all, we’ve told you that it’s probably nothing to worry about — unless it is, in which case you need to get your car to the shop right this very second.

So how are you to tell the difference between normal water in the exhaust and scary water in the exhaust? There are two basic things to consider when making this determination: context clues and other factors.

Context Clues

By context clues, we mean to consider the situation as a whole to see if there’s a reason why there’d be water in your exhaust. Is it especially cold out? Did the dripping start after your car had been turned off for a few minutes? Is the car currently at the bottom of a pool?

All of these are perfectly normal reasons for water to be in the tailpipe and nothing to worry about (well, you should probably worry about your car being in the pool).

On the other hand, if it’s a dry, hot day and there’s no conceivable reason why your car should be dripping water, you should start to be concerned. Even then, though, you shouldn’t necessarily head down to the shop unless you spot other factors as well.

Other Factors

Other factors are all the additional signs that accompany a blown head gasket or damaged piston. These include white or blue smoke coming out of the exhaust, overheating, or odd smells coming from the engine.

These are the signs you should truly be worried about, not the water. The water is just an accessory to the attempted murder of your engine.

Final Thoughts

If you’ve noticed water dripping out of your tailpipe, then there’s probably nothing to worry about. This is a common occurrence that will happen with just about every car at one time or another.

However, if you’ve noticed other signs that something might be wrong with your ride, you should take them seriously and get them checked out right away. This will probably mean an expensive repair — but that expensive repair could save you from needing a brand-new car.