Moisture from tail pipes?

TheUser

Active Member
Jul 25, 2003
1,859
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Springfield, MO
I let my car run for 5-10 min on break at work and when I got out, I noticed some moisture on the ground that the right tailpipe had shot out. At home, It was running and it was wet under both tail pipes. It wasn't puddles, but it wasn't just a few drops either. What does this mean?
 
It really depends on the situation and the way it looks and all. Just so you know however, the most efficient combustion yeilds water, so water out the tailpipes IS good.

The other possibilty is the fact that your exhaust was so cold and being that exhaust gas is so hot, heat meets cold and you get condensation.

Either way, nothing to worry about.

Worst case scenario though is a blown head gasket where coolant evaporates in the combustion chamber, but if this were the case then your car would definitely feel different as well.
 
CH20 + O2 (burning) = CO2 + H2O(water)

Using molar concentrations for this equation (i'm not sure the chemical formula for gas) 1 mol of CH2O would yield 1mol of water... 1:1 ratio... meaning fost9508 you would be correct, assuming gas is CH2O (which it probably isn't)
 
The basic component of gasoline is octane - C3H8. When oxidized (combined with O2 - combustion) the principal components of the combustion process are CO2 (carbon dioxide) and H2O (water vapor). When any car's exhaust system is colder than the dew point of the moisture-laden mixture running through it (water vapor) the exhaust system acts like a big condenser - the water vapor condenses into water in the exhaust system. That's why when it's cold outside, you'll see big plumes of vapor out the back of cars until the exhaust system warms up enough that it's above the dew point of the exhaust stream. It's VERY common that enough water condenses that it will spit raw water right out the tail pipes.

So, in answer to your question " I noticed some moisture on the ground that the right tailpipe had shot out. At home, It was running and it was wet under both tail pipes. It wasn't puddles, but it wasn't just a few drops either. What does this mean?" It means your engine is/was running and winter is right around the corner.

So don't be surprised if you don't see the water come next summer. Now you know why.
 
TheUser said:
I let my car run for 5-10 min on break at work and when I got out, I noticed some moisture on the ground that the right tailpipe had shot out. At home, It was running and it was wet under both tail pipes. It wasn't puddles, but it wasn't just a few drops either. What does this mean?
I'D say you've got a Wet mustang :rlaugh: you'd better take care of that............. :D
 
Of course without proper combustion at the ideal A/F ratio, you get lots of CO. That's why they put Cats on cars. Add the Catalyst of HEAT + AIR to complete the cycle and produce the CO2 and H2O.
 
JB66 said:
Of course without proper combustion at the ideal A/F ratio, you get lots of CO. That's why they put Cats on cars. Add the Catalyst of HEAT + AIR to complete the cycle and produce the CO2 and H2O.


Simply put, yes.. its normal.

This exact thing ticked me off a bit,.. about two years ago anyway..

Had the GF in the car,.. well. GF at the time anyway.. said she didnt "feel the same anymore" yadayada. anyway, I was driving my 95.
She hadnt heard the 90 run.. so, I pull into the driveway right behind my 90 LX 5.0.

She's sitting in the 95 when I fire it up.. BROOOOM.. (I had just washed the 95) the 90 blew ALLLLL kinds of nastyness onto the front of the 95 lol

Sum it up as sibling rivelry I guess... lol

Anyway,.. yes... its normal.
 
Actually there are a BUNCH of other compounds that get produced besides CO2, and H2O including CO, various oxides of Nitrogen (NOx - air is 78% N2, and only 21% O2) and many other trace compounds. But running correctly and as designed from an emissions perspective, the bulk of what you get is carbon dioxide and water.
 
TheUser said:
I let my car run for 5-10 min on break at work and when I got out, I noticed some moisture on the ground that the right tailpipe had shot out. At home, It was running and it was wet under both tail pipes. It wasn't puddles, but it wasn't just a few drops either. What does this mean?

I live just south of you.... mine does it too. :nice: All the crazy weather we've had lately plays a role in it too. Humidity and temperatures have been all over the place. :rolleyes: