Three Kinds of Engine Smoke

Engine Smoke

Dear Dr. Motorhead,

I was watching ESPN last Sunday and was very pleased and excited to hear of Piston’s great accomplishments and success as Captain of the University of Hawaii’s hockey team. I couldn’t believe how many goals and assists that he has accumulated in such a short time. You must be very proud and perhaps a little nervous that he won’t follow his academia and become a professional hockey player. I know how busy you are and your desire for him to transition into your studies and continue with your writings. Continue the family tradition as it were. Notwithstanding, his future contributions to the greater internal combustion and gear head societies.

However, I need to discuss with you my problem. In fact, I think I may have a greater problem than I can possibly deal with. Especially, with my current Executive position as of the American Lung Association. Doctor… my engine is smoking!! I can’t allow this story to leak to the public without first a positive outcome or a proactive position. My job and certainly my credibility are on the line. Please, I need your input more than you can imagine. I need to make a statement before this story gets leaked to the press. Even worse, CJ, the gossip reporter from the Star/Tribune may latch on to this like a pack of mad dogs.

The smoke emitting from my exhaust is white. The situation seems chronic. Doesn’’t matter if the engine was just started or has run for a while. In fact it gets worse the harder you work the engine. The smoke was at it’s worst late this fall, while taking the boat out of the water on a very chilly Saturday morning for winter storage.

This story is true, however I have changed my name to protect my anonymity.
Smoke Stack Lightning

Dear Lightning,
Seems to me I remember a song by that name. I hope you’re not in trouble for any copyright infringement. I’ll forward your letter to Piston. I know he will love to hear your thoughts. U of H is doing very well. They lead the whole South Pacific Collegiate Hockey League. The competition is fierce. All the kids are aware most of the major league scouts are keeping a close eye on the many prospects in this very competitive division. Follow his academia? I thought that was a kind of nut like a filbert, I’m not sure why he would follow these. However, I do know he will choose the best path for him. If he decides on a career in the NHL, perhaps I could solicit Steve Merjanian, Jack Dukes or even Tonka Bob to follow in his footsteps. One step at a time, I’ll take on the challenge as it presents itself.

Now, let’s deal with the smoke issue. There are three types of smoke that emit from an engine, white, black and blue. Actually there is a fourth, however this comes from Todd Warner’s cigar. It’s not uncommon to see smoke emitting from the strangest locations as Todd sneaks around, trying to scoop yet another deal.

 We might as well start with the worst — blue smoke, or bad juju as they say in the South Pacific.   What does this mean? Your engine is telling you something, just as our sparkplugs do. Blue smoke is the result of oil getting into the combustion chamber. The burning of this oil and gas is the blue emission. Although the smoke may vary from a light to a darker shade of blue, the make-up is the same. The darker the blue, the worse your engine’s condition. This blue smoke may also be visible at the crankcase breather. This is the pipe that protrudes from the engine block to the carburetor on our older flathead motors. The oil gets into the combustion chamber through worn piston rings, cracks in pistons, or worn valve guides. Either way, it is time to get your engine into the shop for a rebuild.

Remember as a kid, the old outboard motor you had? It would leave behind little bubbles filled with a bluish oily mixture on the water. That’s because you mixed oil with your gas in a very rich 20 to 1 gas to oil mixture. The underwater exhaust made all these little smoke filled traces. Not only was it very polluting, it made it easy to follow your trail back home when on a strange lake — kind of like dropping bread crumbs in the woods.

Black smoke is a much less menacing problem, caused by an overly rich, or too much gas-to-air ratio burning in your engine. The air and gas mixture needs to be balanced properly. Too much gas and you get this black diesel-like emission. Don’t worry, this is easy to fix; simply an adjustment to the carburetor or perhaps a carburetor rebuild. If you have a newer V8 engine with an automatic choke, your problem may also be here. Sometimes these chokes get stuck and don’t allow enough air to get into the engine. This is easy to check on new engines as well as the older ones in case you are forgetful and forgot to push the choke cable back in on the manual models. Remove the flame arrestor from the top of your carburetor. Look into the choke; there is a large plate just inside the throat or opening. This plate should be in the open position, not closed off. If it is closed, it can usually be manually opened without too much trouble. Push it open and you should be good to go. If it is an automatic choke, don’t forget to fix the problem.

I’m sure your cohorts at the American Lung Association would prefer you to be paddling a canoe or rowing a skiff, however your problem is the sign of a healthy engine. White smoke is formed by water vapor. Many refer to this vapor as steam, but it is not. If your boat is equipped with a thermostat, chances are you will have more white smoke or water vapor emitting from your exhaust pipe than those without. When you operate your boat in the early spring or late fall, this vapor becomes more visible as the air temperature is lower and cannot hold as much moisture. Then the vapor becomes more visible. It is the same as early morning fog above the low-lying valleys or swamps. As soon as the day warms up, the air has the ability to hold more moisture and this visible moisture or fog disappears, and is absorbed by the warmer air. Another way to look at this is, your breath is more visible in January than in July. No way is this steam. If it were, your body temperature would need to be 212 degrees fahrenhiet. So, when the white smoke was worse on the cool fall morning, that is because it was just more visible. When you are working your engine hard, you’re just producing more water vapor. In addition, the more moist the air, the more moisture-laden air you are pulling into your engine and the more moisture you are expelling. For those of you who studied chemistry and physics, P V = N R T is a good formula to remember when you have this discussion with a brain.

Need to know how an engine is performing at a glance? Take a look at the exhaust pipe. If the engine is running perfectly, the inside should be a shinny copper. Too rich, it will be black and sooty. Burning oil or experiencing blow-by, there will be an oily coating or residue.
There you have it, Smokey, it’s just that easy. See you all at the Minneapolis Boat Show. You will recognize me as the one wearing the University of Hawaii hockey jersey. Gee I’m proud of that kid.

Dr. Motorhead.