Black smoke means???

[SilverSage]

I always thought that Black smoke from a diesel meant that you burning fuel without enough air (but making power) and white smoke was un-burnt fuel. When I come down off of steep forest roads with a trailer using low gear and no throttle (mostly brake), I get lots of white smoke no boost and very low temps in engine any transmission. So what’s the scoop on diesel smoke?

 

[DMcPherson]

unburned fuel is black. if you overfuel that is unburned fuel, which is still black. white smoke can be a couple things. if your not getting enough fuel you can smoke white, burning coolant is white also. after you get the white smoke does it clear up and run ok? if so how long to clear up?

 

[hintonJ]

White smoke occurs because engine is not up to operating temps, so it's not hot enough to offer complete combustion of fuel, Black because there is more fuel than there is oxygen available to burn it. How long does it take for you to decsend, and what are the ambient temps when you see this prob? A winter front may help, if it's really cool out.

 

[Graphic man]

White smoke could also mean a timing issue,..... or low compression can also cause it.





Scott

 

[jwgary]

Black smoke = incomplete combustion (too much fuel for ammount of oxygen)

white smoke = no combustion (temps too low to initiate spontaneous combustion of the fuel)

 

[SilverSage]

Thanks All, I understand!!



The white smoke is only when I come down hill slowly with a load and mostly brakes & Low gear, but clears up soon as I use some throttle.

 

[cojhl2]

Thanks All, I understand!!



The white smoke is only when I come down hill slowly with a load and mostly brakes & Low gear, but clears up soon as I use some throttle.

Doya think it might be crankcase oil??

 

[RyanStewart]

Whats the altitude you're coming down from? High altitude can make a diesel do all kinds of weird things, blowing white smoke more when cold being one of them.

 

[SilverSage]

Comming off of Pikes Peak after a Race from about 12000 feet and some times on forest roads at lower elevations. Always slow in low gear and only when desending. When I get down and use the go pedal everything clears up. I not worried about the white smoke just wanted to make sure I understood correctly about diesel smoke.

 

[LEPage]

"Black smoke means??? "

If you're seeing it coming from another truck it means you are in at least 2nd place! :-laf

 

[Vaughn MacKenzie]

If your truck makes white smoke when engine RPM is above idle and you're not touching the pedal then the governor should have the fuel completely closed off- nothing coming out of the injectors. Maybe you have an injection pump problem. Either that or for some reason your engine is drawing in a bit of oil which is burning enough to smoke while descending. You didn't mention what truck you have but I've owned 5 CTDs- everything from a '96 12v to a '03 HO and have never had any sort of smoke under any condition going downhill. Since my '96 is getting up there in miles and showing its age a bit it will roll some blue smoke on a long descent if I start to touch the pedal. Then when the heat builds back it clears up for the most part.



24-valves are known for emanating white smoke at operating temp when the injection pump is on its way out.

 

[Vaughn MacKenzie]

Oops I meant to comment on smoke color as it relates to diesel fuel - -



Black - burning fuel with insufficient oxygen, as mentioned above

White/blue - poorly burning fuel due to cool cylinder temps. Second cause is poor fuel atomization even if cylinders are at operating temp. Caused by air in fuel or injection problems.