5 Reasons Water Comes Out of Your Car Exhaust
Seeing water dripping from your exhaust pipe can be depressing, but it’s not necessarily a serious issue.
- In some cases, condensation can be normal.
- In other cases, it indicates a bigger engine problem, like a blown head gasket.
- In this article, we’ll look at the possible causes of water in your exhaust, from harmless to dangerous, so you can assess the severity and know if repairs are needed.
When Water Comes Out of the Exhaust is Normal
Water coming out of the exhaust is quite normal, unless it’s in very large quantities. At least, that’s what you should understand from this article.
1) Natural Water Condensation
The combustion process is not without its problems as it can produce pollutants. The three most important are water vapor, nitrogen, and carbon dioxide.
When you start your car, water vapor and carbon dioxide mix together. And when you arrive at your destination and park your car, you’ll find this water vapor collecting on the inside of your exhaust pipe. You may notice some water droplets here and there, but this is nothing to be worried about and is part of normal car operation. Condensation is the cause of 99% of all water related emissions issues.
2) Catalysts Produce Water Vapor
Wow, catalytic converters, or “kats”, are so amazing, aren’t they? So incredible that pranksters will try to steal them from your car’s undercarriage as soon as you leave it. In a few minutes, a saw and a very motivated gentleman will have your car sounding like a race car for free. Of course, you can drive without a catalytic converter, but you may make a mistake during your annual emissions inspection or when dealing with the police. It’s best to have one installed.
In either case, the catalyst removes toxins produced by the combustion process and produces some water vapor as a by-product of the process. This water vapor can build up in the exhaust pipe and drip all over the place.
The bottom line is that if you see water dripping out of your exhaust pipe, but the amount is very small, it’s usually nothing to worry about.
3) Bad Cylinder Head Gasket
When your engine gets really hot, things tend to warp. Often, this is caused by a blown head gasket. The head gasket is like a VIP bouncer for your engine, keeping fuel, oil, and coolant from mixing while you’re partying. If this bouncer doesn’t do its job, disaster is inevitable.
If you notice an increase in the amount of water coming out of the exhaust (perhaps a cup per hour), something bad might be going on. Examine the fluid. Is it clear? Or is it a bit brackish and opaque? If it looks a bit cloudy, the coolant may be the culprit. If this is the case, turn off your car’s engine immediately and open the hood.
Take the oil filter cap off and take a peek inside. Does it look milky white? Green? If so, these are telltale signs that coolant is mixing with the fuel. Now the fuel isn’t burning as much, the oil isn’t lubricating, and the coolant isn’t cooling as well.
You’ll end up with a milky, smelly liquid coming out of your exhaust pipe, and you should take your car to a shop as soon as possible. Engine replacements are very expensive – trust me – and you want to avoid it at all costs. Ignore the boy next door who says, “Changing an engine is no big deal, buddy.”
Note: You’ve probably ignored a few check engine lights, service intervals, or other signs until fluid starts leaking out of the exhaust. So be sure to check and see if fluid is being consumed or smelled, about a cup per hour. It’s probably just condensation.
4) Engine Block or Cylinder Head Cracks
Let’s talk about engine blocks and cylinder heads. These are critical parts of your engine and when they crack you are experiencing serious problems. This usually happens because the engine has severely overheated or something has done physical damage to the engine.
In rare cases, using water instead of a proper coolant in extremely cold temperatures can cause it to freeze and expand, resulting in cracks; however, this is very rare with modern antifreeze.
If these cracks cause coolant to leak into the combustion chamber or exhaust system, you will see water or steam coming out of the exhaust. You may also notice that your coolant levels are low, your engine is running hotter than normal, and your car is performing poorly.
If you suspect this is the problem, prepare for a costly repair bill. Repairing a cracked block or cylinder head is a big job and definitely not something you should ignore. Trust me, if you catch this early, your wallet will thank you.
5) Faulty Piston or Ring
Generally, piston and piston ring failures will not cause water to get into the exhaust unless the head gasket is also defective. One way to tell if your rings and pistons are burnt out is to check for black soot residue or oil film on the end of the exhaust pipe.
You may also notice unusual engine sounds, sudden loss of power, increased oil consumption (check your dipstick or oil level gauge (Why BMW?)), and overheating as indicated by the temperature gauge. When checking for these issues, pay attention to the type and amount of smoke coming out of the exhaust when you start the car.
This isn’t too detailed, but if you want to specifically tell if your piston rings are bad, check to see if the exhaust is a dark blue/gray color when you start the engine. This means the piston ring is defective. If you are replacing your head gasket due to water in the exhaust, it is a good idea to check the pistons and rings immediately.
