Seeing water drip from your tailpipe can be concerning, but it isn’t always a big deal. This occurs because water vapor produced in the combustion of fuel in the engine takes the form of water condensation. This is normal behavior for internal combustion engines of gasoline or gasoil vehicles and is especially true when starting up an engine cold.
If water leakage is ongoing or excessive, there can be an engine issue, like a damaged cylinder head gasket or a crack in the engine block. In these cases, it’s best to take the vehicle to a repair shop for assessment and possible repair.
Notice Water Dripping from Your Car Exhaust Pipe? Is This Normal?
Combustion Process
Your car engine operates by combustion. In other words, a series of tiny explosions creates the power to drive the pistons up and down to provide the motive power to move your car forward or backward.
During the combustion process, the combustion gases become exhaust fumes, which must exit the engine through the car exhaust system. However, if you look closely at your tailpipe, in addition to exhaust fumes swirling out, you may also notice some water droplets. Why is that?
It’s Just Condensation
Unless you have blown a head gasket or a leak in the engine coolant system, 99% of the time, any water dripping from your car exhaust is completely normal, and nothing to worry about. After all, it is just condensation being discharged while the engine is running.
You may even be able to notice this dripping when the outside temperature is colder than the temperature in the engine when it has just started.
Here is what’s happening:
- You start your car engine.
- Hot gases begin flowing through the exhaust system.
- Condensation is formed in the exhaust pipe as it cools rapidly due to the outside temperature and the contrast between the heat and the cold air.
- The movement of the exhaust gas through the entire exhaust system forces the moisture out of the exhaust system, and the drips occur at the muffler section.
- Once the engine has run long enough that the exhaust system is at operating temperature, the water will cease.
Most of the time you will find water out of your exhaust in your vehicle is normal. This is a simple form of condensation. More often than not, the same droplets you see coming out of your exhaust look like white smoke, but there is no odor present.
What you are seeing is steam. If your engine is producing white smoke that has a very strong burning smell, you should see a professional, as this could indicate an oil leak. See more about exhaust smoke colors here.
When is it Not Normal?
While most cases of water coming from your car’s exhaust system are normal, there are times when it’s a sign of a problem. An example could be taking a minute and encountering a cup of water for every minute of driving.
If the water was not clear, you may have encountered some antifreeze leaking out, which means you could have had a blown gasket in the engine (usually a head gasket). It could simply notify you that you have a cracked head, which could further allow engine coolant to leak in.
Lubricant Mixed with Coolant
In this case, you will want to shut off your car’s engine, and pop the hood. You’ll want to remove the oil filler cap, and take a look underneath it. Do you see a whitish/green material? This is what happens when motor oil aerosolizes into water or antifreeze.
If you see this, you need to be looking to get your engine repaired immediately. Operating it could lead to serious damage, as oil that has become mixed with coolants will not perform very well to provide hydration to engine parts.
6 Reasons for Water Dripping Out of the Exhaust
Water from your exhaust is pretty normal, as long as it’s not excessive. Keep that in mind above all else from this article.
#1. Natural Water Condensation.
The internal combustion process doesn’t come without its dilemmas, and sometimes that includes some level of pollutants forming therewith, most notably water vapor, nitrogen, and carbon dioxide.
Whenever you fire up your car, there will be some mixing of the water vapor and CO2 first. Then, when your car is shut off and you reach your destination, you will see this water vapor coalesce and come together on the inside of your tip exhausts.
You might see some drips sometimes, but again, you don’t need to be concerned about this water formation, as it’s just a regular part of getting to your destination that just happened to take place behind you. Condensation is the culprit for 99% of water-related exhaust issues.
#2. Catalytic Converter Producing Water Vapor.
The catalytic converter reduces the pollutants produced by your engine before those emissions enter the atmosphere from the tailpipe. It turns toxic gas into less harmful emissions and makes water molecules as well.
That’s why you should expect to see water vapors come out of your tailpipe. In this case, you will know that there aren’t any problems with that catalytic converter, and you can expect to stop seeing water vapors in a few minutes.
Keep in mind that you might see that water vapors can take longer to dissipate in certain circumstances because your engine might warm up more slowly in colder temperatures.
#3. Head Gasket Failure.
When things get REALLY hot, things warp and that is in a lot of cases due to a blown head gasket.
The head gasket is the bouncer of the engine. When it works properly, it makes sure that fuel, oil, and coolant do not communicate with each other during the party. If you have failed in the bouncer, just go on and have yourself a drink because you’ve just stepped into a very deep hole.
If you are seeing more and more water (like a cup per hour) coming out of your exhaust, you’re probably kicking yourself right? Validate the liquid. Is it clear?
Is it a little dirty and opaque? If it’s a little muddy to the eye, it’s probably coolant. If it is coolant, shut your vehicle off and open the hood.
Take off the oil filter cap on top of the engine and take a look inside. Do you see a milky color? Green? If so, it is obvious that coolant is mixing with fuel. Now you have fuel that is not burning as well as oil will not lubricate, and coolant is not going to cool!
You will have some milky-smelling liquid coming out of your exhaust pipe, and you should get your ride to a mechanic by all means.
Motor replacements can be costly—trust me, you don’t want to find out the hard way. Don’t listen to the kid down the street saying, “Motor swapping is not bad, bro”.
Note: You probably ignored a few check engine lights, maintenance intervals, or other signs by the time fluid is coming out of the exhaust, so be sure to validate that the fluid is about a cup an hour, and it smells. As it most likely is the case, it’s not going to be coolant but just water condensation.
#4. Cracked Engine Block or Cylinder Head.
Let’s have a little chat about your engine block and cylinder head. If these crack, you have a problem.
This usually occurs to the engine block and head because it has been badly overheated, or you have just caused physical damage to your engine.
On rare occasions, if the water is the coolant in extreme temperatures, freezing and expansion can cause cracking in the block or head. But with today’s antifreeze products, that is rare.
When your coolant leaks into the combustion chamber or exhaust system, you will be saying hello to steam or water out of the exhaust.
You may not notice it initially if it is steam, but eventually you notice your coolant levels dropping slowly, or perhaps your engine is getting excessively hotter, or the worst of all signs, your vehicle will be losing performance.
If you think you have a problem, just be prepared for the inevitable hefty repair costs. Repairing a cracked block or head is a serious job, and especially one that is not needed. Trust me, your wallet will be happier that you addressed this problem, NOW or in the past.
#5. Bad Pistons or Rings.
Piston and piston ring failure typically will not have water in your exhaust unless the head gasket failed at the same time.
A way to start diagnosing if rings and piston have failed, is to look for black sooty residue, or an oily film at the tips of your exhaust.
You may also be hearing strange noises from the engine, and noticing a sudden loss of power, increased oil consumption (please, check your dipstick or dip meter (WHY BMW?), and overheating if indicated by the temp gauge.
While checking for a few of these, keep an eye on what kind and how much smoke comes out of your exhaust when you first start the car.
While this is broader, but if you’re trying to accurately determine if your piston rings have failed keep an eye on what colour smoke comes out if both your oil and water didn’t change during the running of the engine. If you see a dark blue/gray smoke from your exhaust, this means your piston rings have failed.
If you are replacing your head gasket because you have water in your exhaust, you might as well check out those pistons and rings while you’re at it.
#6. Failed EGR Cooler.
Finally, the EGR (Exhaust Gas Recirculation) cooler. This little device is about recycling to reduce emissions. This is primarily used on Diesel engines, cooling exhaust gases that are then sent back into the engine to be burned again.
Unfortunately, when the EGR cooler leaks, it can be similar as leaving the garden hose on inside the engine. Coolant will end up in your exhaust system which is causing your vehicle to act like a steam engine from the 1800s.
Signs of a faulty EGR cooler are pretty apparent. You would notice white smoke from your exhaust, coolant levels are dropping for no reason, and the engine is running much hotter than it should.
While this is not as catastrophic as a cracked block or blown head gasket, it’s still a get your butt to a mechanic kind of issue.
What Does It Mean if Black Water is Coming Out of My Tailpipe?
It is also normal to notice black-colored steam coming from your tailpipe. It may be that the water drops from condensation have mixed with carbon buildup. However, black residue in large amounts may be due to a failed component so you should take your vehicle to a repair shop as soon as possible.
Similarly, you should take your vehicle to a repair shop if the dripping from your tailpipe is excessive or if you observe a large volume of black smoke – this may indicate that the engine is running too rich.
What to Consider Before Going to a Mechanic?
If you see water coming out of your tailpipe, you should consider a few things when assessing whether this is something serious:
Smoke Color
Determine if there is an unusual amount of smoke coming out your tailpipe and the thickness and color of that smoke. For example, if the smoke is blue this can mean that the oil or some other substance is mixing into the fuel inside your engine or that there is a leak of some kind.
Smell
Again with the sense of smell, you should determine if there is any unusual smell coming out of your exhaust. For example, if it smells sweet there is the possibility that your coolant is leaking.
Liquid’s Consistency
If the liquid droppings from your exhaust are too greasy that is probably a function of oil or unburnt fuel mixed in with the water. Again, keep these things in mind and you should discuss your findings with your mechanic.
Diagnosing the Problem
A great deal of the diagnosis can be simply done using your two original tools, your hands and your eyes. (let him cook!)
First, start up your car from cold and go out back to observe the exhaust tips. Is there steady water flow coming out? You should turn that car off for sure if so, then, go back up.
If there are only a few drips, it is just water condensation and you’re probably fine to drive the car. However, as long, there are no other issue unrelated to the exhaust you are ignoring.