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Why water is dripping from your exhaust.

Water dripping out of the exhaust is very good, isn’t it? Uhh… not exactly.

Water dripping from the exhaust can be very good or very bad. It could mean that your engine has a hundred thousand miles of life left in it or less than 10 miles left.

Most of the time, especially during hot days, water rarely drips out of the exhaust of cars, just colourless exhaust gas. However, it isn’t uncommon to see water dripping out of a car’s exhaust, and it could mean a lot of things

Water is dripping out of your exhaust because…

There are basically four things that can cause your car to drop water from the exhaust. 


Engine heat 

When a vehicle is parked overnight, the engine cools down to room temperature. Through the course of the night, the environment generally becomes cooler than during the day. 

When the engine is started in the morning, the engine oil will need a while to circulate around the different components of the engine and since the engine contains a lot of moving parts, these components will in turn generate a lot of heat for the first couple of minutes after startup. 

A cold morning start

The heat produced heats up the cold air which was in the exhaust before startup and causes the water vapor to be formed. The water vapor then exits the tail pipe as steam or little drops of water.

This is very desirable and absolutely normal.


Car engines are internal combustion machines. They burn fuel (C⁸H¹⁸) in the presence of oxygen O² to produce energy, with carbon dioxide, water, little carbon monoxide and a few other toxic gases as waste products. To understand how engines work, click here

Most cars use gasoline engines which burn fuel through which they produce mechanical energy that is then transformed into motion.

When combustion is optimal in the engine, little water is formed as a byproduct. The water produced is in vapor form and some of it condenses before it exits out of the exhaust, dripping out as water.

This is also very normal and is absolutely desirable because it signifies that the engine is in good health.

Catalytic converter

The catalytic converter is a part of the exhaust that absorbs toxic gases that are byproducts of combustion in the engine to make the cars more environmentally friendly.

Catalytic converter
Catalytic converter

After combustion, the gases formed; carbon dioxide, water vapor, carbon monoxide, and toxic gases; move to the catalytic converter where the toxic gases are absorbed and their sizes are reduced by the catalysts (rhodium, palladium, platinum) in the catalytic converter. During the process of this absorption, little water vapor is formed too, and as a result, we have water dripping out of the exhaust. This is also very normal and absolutely desirable. 


Blown head gasket, worn piston rings, cracked engine cylinder, worn engine piston.

Some years ago, I had an experience with a vehicle, it was a Mitsubishi space wagon, 1999 model year. The vehicle was always dripping water, whether it is a cold day or very hot afternoon. I was even deceived into thinking it was a very okay vehicle until I asked a few mechanic friends what they thought of the vehicle.

It was then that I was told that the particular vehicle had a faulty engine part and that was why it was dripping so much water and that it needed an engine rebuild. 

This prompted me to read more about it, leading to a few findings that could cause this phenomenon. 

Faulty pistons, worn piston rings, blown head gaskets, and cracked engine blocks will cause water to leak into the combustion chamber of an engine. This is a very undesirable thing in a car which will only lead to more problems like rough idling, water mixing up with the engine oil and in very extreme cases, it can cause the engine to knock. 

Blown head gasket
Blown head gasket

It is usually accompanied by overheating, a burning smell and/or smoke filling up the cabin.COOLING SYSTEM: HOW-IT-WORKS (PART 1)

One of the ways the vehicle shows these flaws is by dripping water out of the exhaust, but in this case, the water that drips out is usually very much, it shoots in jets. Another common characteristic of this is that the water is escorted by blue smoke in this scenario.

A faulty engine situation

If you notice this, have your car towed to your mechanic to prevent further damage to it through driving. Have it checked and carry out the repairs necessary else you risk losing the most important part of your car, which is your engine.

Steam differs from smoke in that steam disappears a few seconds after leaving the exhaust while smoke doesn’t, it hangs around for a while longer.

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