Black water coming from exhaust pipe at startup

[chbrow10]

What causes black watery liquid to come from the exhaust pipe at startup? Carb has good vacuum. Idles at ~700 rpm.

 

[Seth S]

Two things. 1. The combustion process creates water as one of its byproducts and that water mixes with carbon build up which coats your exhaust. The carbon dissolved in the hot water and comes out the tail pipe. When it’s cold in the winter the smoky stuff you see coming from your tail pipe is mostly water vapor.
2. There is likely some level of condensation in your exhaust system as well.

If your engine were perfect and 100% efficient the only emission would be water. one of those cool science things. Oxygen on its own will accelerate combustion and hydrogen on its own is highly flammable. Combine the two through combustion and you get pure water which extinguishes Fire.

kind of like everyone likes getting laid and getting off but most people don’t like getting laid off.

 

[OSS]

Seth is correct- but the engine exhaust shouldn't be coating the inside of the exhaust pipe with that much soot. My exhaust pipe would dribble water and steam in the morning (like all cars do) but it never spewed black crap out the pipe - ever-in 30 years and 275,000 miles

 

[TRAIL TAILOR]

Seth is correct- but the engine exhaust shouldn't be coating the inside of the exhaust pipe with that much soot. My exhaust pipe would dribble water and steam in the morning (like all cars do) but it never spewed black crap out the pipe - ever-in 30 years and 275,000 miles

Correct. I have a new to us 60 that is running REALLY rich and blows black water no matter what time of day; morning or afternoon; cold or hot... Take the richness out and the water will most likely be more clear. All my other 60s have some condensation "burp" as I call it, but the black tells me its too rich and needs some carb and valve tuning.

J