Engine Smoke

[dale farley]

I've probably reached my quota of questions in the last couple days, but I have another. I let my bus idle for about 15 minutes this evening then pulled out on the highway. When I took off, I got a terrible cloud of white smoke (obviously oil). It lasted for just a few seconds, but was really embarrassisng. I looked like a truck killing mosquitos.

It acted like a bad case of leaking valve seals, but that is normally most obvious when you turn off the motor then start it a few minutes later, allowing the oil to drip past the valve seals into the bottom of the head, then blowing it out when you start the engine.

Any suggestions as to what may have caused the smoke? I don't really know anything about the 8V92. Does it burn more oil than a 4 cycle diesel?

[JIM CHALOUPKA]

Dale, White smoke could be a coolant leak. JIM

[Jon Wehrenberg]

Ditto.

On a sub zero morning immediately after start up white smoke is unburned fuel. After the engine is running and had gotten warm my first thought would be what Jim said.

Smell it. You will know.

FWIW, I had a hairline crack between two valves in my 8V92 that allowed coolant into the cylinder. There are a number of reasons for coolant getting into the cylinder and none of them are good news.

[dale farley]

I suppose I will end up at Detroit Diesel for this one.

[Jon Wehrenberg]

Dale, before you take steps to mortgage the farm try to find out what the white smoke is. Smell it because if it is fuel or coolant you are going to know.

Coolant can turn out to be expensive, but fuel might be an injector.

[dalej]

One other thought, did by chance someone put a lighter oil in? You need a straight 40 weight in it. Also was it on high idle? A minute is max on low idle.

[dale farley]

Jon,

I really don't think it is fuel because it was over 60 degrees outside in the afternoon, and it should have been dark smoke if it was fuel. Once I took off and got down the road about 1/2 mile it ceased to smoke, even though I went 15 miles and stopped and started several times.

I will see what it does when I go back to get the bus in a few days, and if it repeats itself, I will attempt to determine the sourse by the smell of the smoke. I certainly vote for a bad injector vice a cracked head or other serious problem. I would welcome it being an injector that was leaking fuel in the head then burning/blowing it out when I accelerate. Thanks for the suggestions. Dale

[Jon Wehrenberg]

Partially burned fuel will be black.Typically that is what you see when you mash the pedal and the turbocharger has not spun up enough to supply enough air for complete combustion so the rich mixture is the black puff out the exhaust.

Raw fuel however is white. But so is coolant.

[dale farley]

Jon, I now better understand what you are saying about the injector. I called a couple Detroit dealers and one of them mentioned that it might be an injector. I asked why it wouldn't be producing black smoke, and he said because I would probably still be getting enough air to keep the smoke white. He said it will definitely produce white smoke if the injector is leaking, but the cylinder is still getting sufficient air.

I was thinking about an engine putting off black smoke when it is running too rich, but that could be from a lack of air just as much as an abundance of fuel.

The technician said the problem may be finding out which injector is causing the problem. He said it could be one of the small poppet valves sticking intermittently and may be difficult to locate. I hope to be able to verify it is a fuel problem the next time it happens. I see your last post validates exactly what the technician was saying.

[Jon Wehrenberg]

RR,

Maybe this is wishful thinking, but if I were Mr. Detroit Diesel my DDEC reader would be able to zero in on the problem, if not by accessing cylinder specific data, but by telling the solenoids (which are part of your electronic injectors) to stop firing so you can see which cylinder is least affected by the misfire, and thus may be the culprit.

You may be able to at least cut the number of choices in half by monitoring your pyros. If one has changed from its normal range at least that might be a clue to where to lok

If you can verify the white smoke is fuel with the sniff test, maybe a good run will be all that is necessary to deal with an intermittant problem and get everything back to working smoothly again.

If it is coolant I would drive it right to DD.