Car "spits" water droplets from tailpipes.

6

66miles

Senior Member
Hi all,

I guess everyone has noticed at some time or other, how often, (usually when idling), cars will "spit" water droplets from the exhaust tailpipes? I have seen this from quite a number of cars of all makes and models, both old and new, so I understand it can be a normal occurrence.

I know for example, that a 239ci flathead idling at 500rpm will ingest somewhere around 32 cubic feet of air through the carburettor every minute. Depending on the degree of humidity in that air, a certain amount of water vapour will be generated through the combustion process. That water vapour then travels along the exhaust system, condensing back to water as it is cooled by the steel of the pipes. I have even read (somewhere), that the process of burning petrol, or any hydro-carbon fuel for that matter, produces a certain amount of water vapour in it's own right, regardless of whether there is water in the surrounding air or not.

OK, so that's the theory, but how is a guy supposed to know "how much" water is normal to be spitting out the back of an exhaust system? I recently had a problem with water getting into the oil in my '47 merc, but have since changed the head gaskets, and the problem "appears" to have gone for now. The motor looses a small amount of water anyway from a leaky water pump, so it's hard to know for sure where the coolant goes. When idling ( it's often humid where I live), she spits droplets from the pipes. Without going to the trouble of collecting and measuring the amount, I would guess maybe a teaspoon a minute per pipe.

Does this sound normal?
 
I just went thru a similar situation. I noticed a more than usual amount of water on the floor under the ends of the tail pipes. I placed a clear glass under the pipes to collect the water......sure enough the water was green...anti freeze out the tail pipes. Pulled the heads....replaced the head gaskets....had the heads cut 10 thousands......problem solved.
 
Great reply harleynut. Don't know why I didn't think of that! Shoulda payed more attention in school I guess. I'm running straight water in the cooling system at present. I was going to flush the system and fill with a 50% glycol mix (green will do just fine). As you so rightly point out, if it then spits green water, there is a problem somewhere. Otherwise, it's just good old atmospheric stuff!
 
Water usually only comes out as vapor if there is moisture in the fuel or from condense in the carburetor venturis. Fluid water drizzling out the pipe can be a sign of problems if the engine is thoroughly warmed up.
 
many many gallons of water come out the pipes as water vapor.the water condenses in the pipes when cold and drips out.on cooler days you can see whose cars have only been running for a short time as you will see the vapor, most mufflers have small hole in them at the bottom above the crimp in back to let the water drain out.shouldnt drip when fully warmed up.
 
66miles said:
Great reply harleynut. Don't know why I didn't think of that! Shoulda payed more attention in school I guess. I'm running straight water in the cooling system at present. I was going to flush the system and fill with a 50% glycol mix (green will do just fine). As you so rightly point out, if it then spits green water, there is a problem somewhere. Otherwise, it's just good old atmospheric stuff!
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66miles ........................
Don't buy the 50% mix. You are paying antifreeze price for water ? Buy the real stuff and mix it yourself.
MIKE :) (mikeburch)
 
My engine doesn't use any oil between changes but I do add a little MM oil to the gas. During warm-up on cold winter northeastern mornings water/condensation does drip from the exhaust pipes .... it shows no green color but if it forms a small puddle I can see a thin oil film on the surface of the water.

Always had condensation from cold exhausts. I use to drill a small hole in the back-bottom of the mufflers to let it drain out - helped extend the muffler life.
 
Rotorwrench. I'm no expert on much at all (ask my wife). But I've always been told that ANY motor will produce water vapour from the exhaust, as a result of water vapour that is naturally present in the air we breath. Some other "experts" also assert that water vapour is produced as a result of combusting ANY hydrocarbon fuel.

As I said mate, I'm NO expert, but I know what I see. My wife"s late-model Ford spits water out of the tailpipe too. The only difference I see is she can drive 100 miles down the highway, any time she feels like it, but I only run my old girl in the garage cos she's not legal to drive on the road.
 
66miles said:
, but I only run my old girl in the garage cos she's not legal to drive on the road.
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That's adding to your "issue".

Put in antifreeze...my bet will you'll still get the drips/drops...take a touch and taste it, most likely won't taste "sweet" (ya won't die...lol), showing it's just from the exhaust system.

Now, if it drips green, or tastes sweet, then yes, coming from the engine somewhere.
 
Good advice Mike B! As harleynut suggested earlier, that water could be coming from just about anywhere (even from the heavens above). But I don't believe the good Lord has gotten round to adding ant-freeze to raindrops yet...
 
66 if my reply helped...I'm glad....after reading your post, just had to add my "2 cents".....when mine did it I was a little panicked, thinking cracked block....freeze plugs......didn't know what to think
 
If I remember correctly, one gallon of gasoline when burned in an engine will produce eight gallons of water vapor. Which is why we see condensation trails from aircraft at altitude. And the heavier the trail, the more humidity aloft. We don't have that problem on the ground but have all seen a tailpipe steam on less than warm days. Modern mufflers will have a weep hole in them to allow water to escape that condenses and does not flow out the tailpipe. And, yes there are times that water vapor out the tailpipe indicate problems and others have covered that situation already.
 
Thanks again Harley. Like you, I have contemplated EVERY possibility. Most of them not good. Your tip on the green water seems so obvious now you've mentioned it that I cant for the life of me figure why I never thought to do it!

I'll be putting the green stuff in the old girl tomorrow, and will let you know whether my car is raining anti-freeze or just raindrops.
 
deucemac said:
If I remember correctly,when one gallon of gasoline burned in an engine will produce eight gallons of water vapor. Which is why we see condensation trails from aircraft at altitude. And the heavier the trail, the more humidity aloft. We don't have that problem on the ground but have all seen a tailpipe steam on less than warm days. Modern mufflers will have a weep hole in them to allow water to escape that condenses and does not flow out the tailpipe. And, yes there are times that water vapor out the tailpipe indicate problems and others have covered that situation already.
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Glad I know How to Swim !!!!!! lol :D
 
The major products of combustion when using a hydrocarbon fuel are CO2 and H2O. True if the fuel is gasoline, diesel, wood chips, natural gas, propane,...

Incomplete combustion adds unburned hydrocarbons and CO (carbon monoxide) to the mix.

(There is some additional stuff, usually of minor quantities although of major concern for the global warming folks.)

The H2O in the exhaust is largely unrelated to the relative humidity of the incoming air. The higher the relative humidity when the exhaust hits it causes the H2O in the exhaust to condense more effectively and become more visible, but the H2O is there regardless.

Changing the fuel to pure hydrogen, as has been proposed, takes the carbon out of the mix and eliminates (far all intents and purposes) the CO2 in the exhaust. (No 'C' in the fuel, no 'C' to make CO2.)

Of course, electric cars don't emit.... well .... as far as the car goes. All they do is move the emissions back to the power generating plant. And nobody has bothered to study the effects on the climate by extracting power from the wind. (There ain't no free lunch!)
 
All most every old Ford I have seen spits water at start up. A lot of them continue to spit after warm up. I put a bottle of heavy duty Barrs stop leak in every engine which stops the water spitting. Sometimes it takes two bottles and no it don't clog the radiator as some people state, just pour it in slowly with the RPM's increased a little. It is also a water pump lubricant. G.M.
 
G.M. said:
All most every old Ford I have seen spits water at start up. A lot of them continue to spit after warm up. I put a bottle of heavy duty Barrs stop leak in every engine which stops the water spitting. Sometimes it takes two bottles and no it don't clog the radiator as some people state, just pour it in slowly with the RPM's increased a little. It is also a water pump lubricant. G.M.
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WHOA. I wouldn't advise pouring Barr's Stop leak unless you can prove it's something other than the NORMAL condensation, and even then I'd hesitate, not to mention two bottles....which needless to say is not going to stop normal condensate from spitting out almost daily.

Regarding "warm up" some cars require significant road time before the pipes get hot enough to steam off the water. On my 302 Falcon, the water actually drips from the joint of the muffler and tailpipe.

I have a '95 Grand Marquis that the water literally pours out the pipes as I climb my driveway some mornings. Absolutely nothing wrong with it. Later day Fords, Mercurys, and Lincolns (both 4.6 modulars and older 5.0) tend to accumulate a lot of condensation in the exhaust.
 
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