Sunday, February 17, 2013

Diesel Engine Exhaust Defining Different Smoke Color

A Smoking Diesel Engine

What Do The Different Colors Of Smoke Mean?

Thank you to the EPA Dept.

The color of the smoke coming out of a diesel engine that's not running properly or showing signs of poor mileage can tell you a lot and is the first step when you start your troubleshooting process. Smoke colors to take note of are black, white and blue.

Since there are so many different diesel engine manufacturers and configurations the plan of attack depends on the engine model especially when dealing with the fuel system. 

When there is an imbalance between air and fuel meaning too much fuel or not enough air induction Black Smoke will occur. Checks you can perform:

* Check the air filter for a restriction.
* Check for faulty injectors or injector pump.
* Check Turbocharger boost reading or inspect for any failures (turbine / compressor wheel)
* Check the cylinder head valve adjustment.

White Smoke means there is inefficient combustion within the engine cylinders.

* The engine timing or injection pump timing could be out of spec. or there is an internal failure
* Air in the fuel causing starvation to the injection system.
* Low engine compression
* A Possibility of water in the fuel

* If you get coolant loss and white smoke that will indicate a possibility of a faulty EGR or "hopefully not" a cracked block. There are several others mishaps that could happen these are just a couple examples. Case in point: We have an engine with a cracked block that was using excessive amounts of coolant and blowing white smoke out the exhaust. This is where an oil sample really comes into play. A high level of sodium indicates coolant in the engine oil.

Blue Smoke The term "burning blue" is well known and that's caused by excessive engine oil getting into the combustion chamber.

* Worn compression rings or oil rings
* Worn cylinder bore causing blow by and excess oil to enter the cylinder
*  Engine crankcase over full
* Oil entering the fuel system

Of course this is very general and is meant to get you thinking when the smoke develops more than usual. cold starts in the winter season will produce white smoke which is normal. This will clear up once the engine reaches operating temperature. The diesel engine is your friend as long as you jump on small problems before they get bigger. :)


Darren said...

yes we haved talked before, on a 97 thomas RE school bus with a 5.9 with a fan that stays on if i put the air selanoid wier from terminal 87 to 87awhitch is 12 volt it will disengage the fan,the book i have shows a 190 wier running from a fuse/relay (this bus has a relay here) to a air teamp senser I traced it and it came out right next to the injecter pump fuel selanoid plugin (wich will plug into it to and whin you do the air selanoid to the fan will dis engage whin the key is on but whin you krank the engine it wont start Im in need of some help if you can! thanks Darren.

Jimmy Coss said...

Hi John, Like your blog site, very helpful as I know next to nothing about diesels. I am a fair backyard mechanic at best. I looked at an International 46 or 4700 dump truck today. It starts everytime and keeps idling, but when you juice it, it stalls or if you drive it and stop, it will stall. It also after awhile started smoking when reving it up. Owner said it has been sitting for a few years and he thinks it is the fuel filters and the fuel itself?? I love the truck but am afraid to buy it not knowing what it is. Any help in this regard is much appreciated. Many thanks, Jimmy