I believe it is normal to have moisture in the exhaust when the car is started, but how much is normal? When I start the car I am getting water in the exhaust form both pipes enough that I can wipe it off the floor. If I hold my hand behind the tailpipe when I remove my hand it is like I had sprayed my hand with a spry bottle. This does stop when the car is at temp but appears to have some steam at times. No oil in water and no water in oil. This is a freshly rebuilt motor that I really haven't driven yet, just around the block a few times. It is a 68 400 .40 over edelbrock heads and RPM manifold mondello cam designed for these heads. I have not had to ad allot of water but some. I hope this is not uncommon but I don't know, as always any insight is appreciated.

 

Depending on the temp and humidity I've seen water splash out of exhaust systems. If it smells like coolant, you have a problem. If it persists say 20 minutes after the car has reached temp you may have a problem.

 

At this time I am running straight water no antifreeze all I can smell is exhaust. The temp was about 55 when I started the car today but I did not drive it, it was just in my shop.

 

X2 it's a by product of internal combustion engine,not to worry.

 

I'm more inclined to attribute it to condensation in the exhaust system that does not get much chance to be evaporated off in a car that may not be driven much.

 

Great to hear thanks I thought that was the case but also thought it was worth checking out.

 

Watching the girls during high school chemistry, eh, Chris?

In general, combustion of organic compounds oxidizes them to carbon dioxide and water.

Specifically, the equation for combustion of hydrocarbons is:

CxHy + zO2 ➞ xCO2 + y/2 H2O

(where z=x+¼y)

So, if you have perfect combustion occurring, you will have CO2 and water coming out your tailpipe.

In reality, the combustion isn't perfect, so there are a lot of other compounds released as well (collectively called "air pollution"), but water is still a major product of combustion. It can be seen in the vapor plumes from the smokestacks of factories and power plants, and in the condensation trails of aircraft.

Have you ever driven any car before this one? All cars produce water, in direct proportion to the amount to fuel consumed, so if you ever owned another car, it did exactly the same thing.

- Eric

 

Thanks Eric great info and yes I have owned several cars other than this one I have just never seen this much water come out of the tailpipe before. I have also never spent the amount of time or money on a project as I have spent on my 442, so I am undoubtedly paranoid and I seem to notice lots of things I would not have noticed before! Thanks again for your insight and help I really appreciate it!

 

Water vapor anyway.

 

Water vapor (gaseous water), steam (water vapor under pressure), liquid water, and ice are all water, and water vapor condenses into liquid water as it travels though a cool exhaust pipe.

- Eric

 

I would drain enough water out to have a 50/50 mix of anti-freeze. Its not good to run just plain water in there anyway. Then keep an eye on your water level in the radiator and you'll also be able to smell the anti-freeze coming out your exhaust.

 

And if the car is driven far/long enough, the exhaust pipe won't stay cool. So like I said, its probably due to the car not being driven much, often the case with classics.

 

Agreed. Pure water in your cooling system facilitates corrosion.
Antifreeze has corrosion inhibitors.

It's okay to put in plain water when assembling after a rebuild to see if you have any leaks, but you should never leave an engine with only water in it for any length of time.

- Eric

 

Well... maybe its the moist air we have in the Pacific Northwest

As long as your radiator isn't going down its probably fine.

Eric, I rebuilt a 455 in the late 1980's for a Cutlass Supreme that chugged steam more often than not. I put about 100,000 miles on it and went through three sets of mufflers. I really got my moneys worth out of Midas! The radiator never went down and I was commuting 50 miles each way to work, so it got warmed up well. Maybe I had the winning combination that burned the fuel well enough to always puff out steam. Don't know exactly what was going on, but since the radiator wasn't losing volume I didn't worry about it.

John

 

You'll blow water (liquid) until it warms up, then you'll blow steam. If everything is warmed up well, the exhaust should dry out as it cools off once parked. This is why one can see steamy exhaust in the winter, which does reduce, but will not stop totally, as the car warms up, depending on how cold ambient is.

 

Actually (and people hate me for this)...

What you see in the winter isn't steam.

It's liquid water droplets that have condensed from the water vapor (or steam) in the exhaust.
Water vapor is dissolved in the exhaust and invisible, hits cold air, condenses into liquid water droplets, becomes visible, disperses and re-evaporates into water vapor as it does (at a lower concentration once in the open air than it was in the exhaust).
The coder it is outside, the longer it takes for the water droplets to re-evaporate into water vapor and disperse (which is why jet aircraft con-trails last so long way up there where its really, really cold).

- Eric

 

Yes, a fair amount of "water" (certainly enough to wipe off the floor) is normal and will be even more pronounced with larger exhausts.
But what hasn't been mentioned here is that this is one of the reasons when a car is started (especially in colder environments), it is important to let it fully warm up and dry out the exhaust. That moisture is acidic and will greatly acceleration the deterioration of an exhaust system. There is also condensation in the crankcase too, so let it get hot!

 

Harrrumpf. I suppose that is correct. You'll pardon my generic usage of the term steamy.

 

"At this time I am running straight water no antifreeze"

You realize that it freezes around there, right?

 

Many yrs ago, say early 70's I read in Popular Mechanics I believe, that for every gallon of fuel u burn ur engine produces a gallon of water.