Last week I noticed what looks like water dripping from my exaust, not alot just little drops. It seems to only do it at start up, or maybe I only notice it then. It's a 01' 4.3L 2WD Blazer. What could cause this ?

 

its a property of combustion. the main by-products of burning the gasoline are water vapor and carbon dioxide (also a little carbon monoxide, and a few other assorted gasses). you only see the water at start up because after the engine and exhaust warm up, the water vapor does not condense in the pipes.

soo its completely normal. now if you have the mississippi river pouring out of your tail pipe, there might be other issues..

 

Thanks. I wasn't real concerned, just a little curious.

 

All cars do this. no worries.

 

The water vapor is a by-product of the catalytic converter. not the engine.

 

but isntH2O still a by product of complete combustion?

I thought wolf pack was right on.

?

 

http://www.meineke.com/stuff_about_c..._catalytic.asp
Click on the Oxydation Cayalyst to understand how the water vapor is created.

 

There is a tiny hole just behind the cat and that is most likely where you see it dripping from , like said it's totally normal especially on start-up !

Zed

 

the amount of water vapor created from the cat. converter is miniscule to the amount produced by combustion. According to the article hanr3 posted, the cat reduces the remaining oxides and hydrocarbons into water vapor by a catalytic reaction (ie small burn).

The exhaust gas simply cannot contain enough poisonous oxides and unburned fuel to produce the same amount of water as the engine, since the 2 largest products of combustion are CO2 (which is not affected by the cat) and water.

Water vapor from combustion >> water from cat.

 

Water condensation came out of tailpipes long before the advent of catalytic converters.