Oil or soot from exhaust?

[PSL_240z]

Okay, new forum software. Lets try this thing out.

 

I have just changed the oil on my z for the first time. After draining, changing the filter, and refilling, I backed the car into the garage (I usually face the car the other way). When I got it back in there I revved the engine one time and my wife told me that I just blew crud all over the cabinets behind the exhaust. When I got out and looked, it did look oily. When I touched it, it seemed more like black water.

 

1) See the poll above (oil water or ??)

 

2) Is this normal, or what does it indicate something is going wrong?

 

3) Do I need to do anything about it (engine rebuild, or something simple?)

 

Thanks in advance! Look forward to trying out this voting thing.

 

Scott

[ktm]

.....and this is why I no longer start my car if I back it into the garage! I covered the wall like you. After I repainted the garage walls I will push the car outside before starting up now. I still leave a little mark on the ground though.

[Dtsnlvrs]

One of the byproducts of all Hydro-Carbon combustion is...drum roll please...WATER. Until your exhaust gets hot, that water will transform from a gas (steam) to a liquid (water and water vapor). This liquid water will pick up all the carbon soot in your exhaust..esp carbed engines...and throw it out the back. What it does tell us, is that you have incomplete combustion during some part of your cycle...could be overly rich or not....my Dyno AFR's look pretty good..for making power, but I have a sooty tailpipe FWIW

[jyz77]

wow, i always figured that the stuff comming out of my tail pipe was too water like to be oil and was sure it was from a rich condition.

[PSL_240z]

Yeah, I didn't think twice until I splattered my cabinets! Only then did it look black. Got me worried I bought a POS. I have owned and worked on quite a few cars, but this is my first carbureted car. Most questions stem from the fact that the oldest car I have personally worked on (until now) was an '88 accord, and a 89 240sx.

[beermanpete]

Despite the poll results (and my own vote for soot), it could be either. Half-burnt fuel and half-burnt oil will both result in black particles. Is there smoke associated with the problem? What color is the smoke? What color are the spark plugs? Does your engine consume oil? Was the choke on fully?

 

To determine the source of the black particles requires diagnostic work on your part. All we can do is hypothesize, guess, and ask a lot of semi-pertinent questions.

 

Cars, especially older cars (due to design or wear) produce pollution. Your car might be perfectly fine. Perhaps you should not start it when the exhaust is pointing at the Mona Lisa.

 

 

Peter

[PSL_240z]

Since I can easily obtain a sample of the black junk, is there something I can do to test if it is fuel or soot? Light it on fire, mix it with water or alcohol?

 

I haven't had the car long enough to know if it is consuming oil, and haven't driven it that much. I have retuned the carbs, so it could be a little rich. Since I have tuned the carbs, I need to replace the plugs so I get a better reading from them (since it was rich and lean since I first changed it)

 

I am also glad that there is not a lot of alarm with this type of post. I dont think it is a severe issue based on the comments I have seen. I intend on a rebuild or different engine anyway, just wanted to know if I definitely needed a new one.

 

Thanks,

Scott

 

Despite the poll results (and my own vote for soot), it could be either. Half-burnt fuel and half-burnt oil will both result in black particles. Is there smoke associated with the problem? What color is the smoke? What color are the spark plugs? Does your engine consume oil? Was the choke on fully?

 

To determine the source of the black particles requires diagnostic work on your part. All we can do is hypothesize, guess, and ask a lot of semi-pertinent questions.

 

Cars, especially older cars (due to design or wear) produce pollution. Your car might be perfectly fine. Perhaps you should not start it when the exhaust is pointing at the Mona Lisa.

 

 

Peter