I know that when you see smoke coming out of the exhaust, each color tells you something else about the status of the engine.


I'm not sure I have this correct, but would appreciate it if someone could clarify what each color means.

1) White
2) Blue
3) Black
4) Gray

When I start mine, for some reason now I always get a puff of black. I think that means the carb is set too rich, but thought I check here with the experts!

|UPDATED|6/23/2004 7:39:16 AM (AZT)|/UPDATED|

I'm no expert, but I thought white mean you are burning coolant, black means rich fuel mixture, blue possibly oil? Gray? I guess a mixture.

Found it, http://www.bellaonline.com/ArticlesP/art10101.asp

White smoke: White smoke is caused by water and or antifreeze entering the cylinder, and the engine trying to burn it with the fuel. The white smoke is steam. There are special gaskets (head gaskets are the primary gaskets) that keep the antifreeze from entering the cylinder area. The cylinder is where the fuel and air mixture are being compressed and burned. Any amount of antifreeze that enters this area will produce a white steam that will be present at the tailpipe area.

If white smoke is present, check to see if the proper amount of antifreeze is inside the radiator and the overflow bottle. Also check to see if antifreeze has contaminated the engine oil. You can look at the engine oil dipstick, or look at the under side of the engine oil filler cap. If the oil is contaminated with antifreeze, it will have the appearance of a chocolate milkshake. Do not start the engine if the oil is contaminated with antifreeze, as serious internal engine damage can result.

How did antifreeze get in the oil or cylinder in the first place? The engine probably overheated and a head gasket failed due to excessive heat, thus allowing antifreeze to enter the cylinder (Where it is not meant to be).

Blue Smoke: Blue smoke is caused by engine oil entering the cylinder area and being burned along with the fuel air mixture. As with the white smoke, just a small drop of oil leaking into the cylinder can produce blue smoke out the tailpipe. Blue smoke is more likely in older or higher mileage vehicles than newer cars with fewer miles.

How did the engine oil get inside the cylinder in the first place? The car has many seals, gaskets, and O-rings that are designed to keep the engine oil from entering the cylinder, and one of them has failed. If too much oil leaks into the cylinder and fouls the spark plug, it will cause a misfire (engine miss) in that cylinder, and the spark plug will have to be replaced or cleaned of the oil. Using thicker weight engine oil or an oil additive designed to reduce oil leaks might help reduce the amount of oil leaking into the cylinder.

Black Smoke: Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

How did the fuel get into the cylinder in the first place? Some of the causes of excess fuel are a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or computer sensor. If black smoke is present, check the engine oil as in the white smoke example to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil. Call your mechanic and advise him of what you have found.

vmikalinis said: How did antifreeze get in the oil or cylinder in the first place? The engine probably overheated and a head gasket failed due to excessive heat, thus allowing antifreeze to enter the cylinder (Where it is not meant to be).

another symptom youll see if you have water entering cyliner is that if you start your car without the radiator cap on ... water will shoot out.. its pretty cool but definitely not a good sign

All good accurate info.
Gray is a combination of black and white. And is a combination of water and rich condition.

One more thing. If it smokes white and clear up after several miles, it could be moisture condensation in the exhaust system. All cars get some of this. It does not start until the exhaust warms up. When it builds up enough, you get the white smoke without any water problems. But if the white smoke is constant and does not clear, look at coolant.

If you have deposits from rich condition in the exhaust, then turn the water in the exhaust to steam, you get grey smoke. Again, if it clears up, no problem. Constant smoke is a problem.

Here's one Ken may be able to help with. I have no smoke and oil looks ok and coolant is good. I constntly have moisture build up in the rocker cover oil filler caps. I have a cap on each side. This moisture is enough to create a grey sludge to build up on the inside of the rocker covers. I will be dropping the oil this weekend to see if I have any contamination in the sump. All I can think of is that the engine has been submerged at some time and contamination has occured.

Chips, it did not take a bath. The gunk is from condensation in the engine. If you clean it all out, it will come back. The PCV system is not present or not working. The PCV Positive Crankcase Ventlation, provides a fresh air flow in one side of the engine and out the other. The air flow removed the fumes from blowby, oil fumes, and condensation.

With a breather on each side of the engine, you vent the crankcase to air, but have no flow. This shortens oil life due to contamination build up, and causes the condensation, and the gunk.

You need some kind of a crank air flow system. Either connect a PCV system to the intake, the headers if equiped, or install a vent fan system. If you have a PCV system it is not working.

|UPDATED|6/17/2004 7:21:59 PM (AZT)|/UPDATED|

I have also seen white smoke caused by transmission fluid being sucked into the engine by a faulty modulator on the tranny through its vacuum line,(or is my memory that bad?)
Jules

82collectorshark said: I have also seen white smoke caused by transmission fluid being sucked into the engine by a faulty modulator on the tranny through its vacuum line,(or is my memory that bad?) Jules

yes this can happen... but dont remember what color the smoke was...... just remember beating my head against a wall before finally finding it.

thanks Ken, I didn't think of that. I can easily remove one of the vent caps and put in a PCV valve to the intake.

Once again the Master has spoken.