Diesel exhaust color meaning?

[wsucougarx]

First off, Doghead I did do a search and found nothing.

This question has been lingering in my head for sometime in regard to diesel exhaust color. What are the causes, diagnostically what can it tell you about the engine, and what should be done if you have a certain color. The colors ranging from white, bluish white, brown, and black. Now specifically, I am interested in brown smoke. Can anyone tell me what is causing brown smoke? I've seen a number of "C" engines w/"C" turbos w/brown smoke.

 

[Stretch44875]

This is what I have been told, white is unburnt fuel, I see that when starting, or cold engine. Black is too much fuel. (and lots of fun) I have some blue smoke at idle on mine, belive it's from running used oil. Never seen brown before.

Dennis

 

[cattlerepairman]

Shades of black relate to the fuel quantity injected in relationship to the air available for combustion. In the absence of computer controls with a "mapped" diagram for fuel injection, it is easy to achieve a mixture that is a bit too rich, for example WOT under full load. Black is basically unburnt fuel. Also seen with air intake restrictions (too little air for the quantity of fuel injected). Also, wrong injection timing, for example if you have a leaky injector that drips fuel into the cylinder after combustion already happened will cause black smoke.

Whitish-grey is often seen on startup and when running cold. I think it is condensation and perhaps incomplete combustion when the engine is very cold. If you are leaking coolant into the cylinders (example: headgasket failure) you also see white smoke, even when fully warmed up.

Bluish usually means engine oil is burning (also often combined with an acrid smell).

Brown.....if you didn't put s**t into you tank, it must be rust flying out of your pipe (only joking here).
The colour of the smoke is determined by the type and size of the unburnt particles in it. That means that, invariably, you will see shades of different colours at different times.

 

[chvss65]

white can also indicate anti-freeze leak into combustion chamber, but a person would smell anti-freeze in the exhaust

Sorry this was stated about
speed read too fast----haha

 

[HeadWizard]

OK, so I guess it's my turn to be the TM police. Fully described in the -34 TM if I remember correctly.

 

[WillWagner]

_Black, not quite enouge air to complete the combustion process...the black is soot, excessive black anyway, the multi's like to run that way
_White, smelling of fuel, Correct amount of air, just an incomplete burn usually due to cold cylinder temps or timing...kinda the same as black, but black is a fast burn while white is a slower burn.
_White that goes away the farther it gets away from the pipe, water or coolant..you'll smell the coolant!
_Blue, Oil! Could be a turbo, but the smoke will start after the turbo gets some temp in it that will start the oil smoking, or a cylinder/valve issue...turbo, a bad thing, don't run it like that. Cylinder/valve, depending on what kind of noises it's making, you can run it, just keep an eye on the oil level.
_Brown, The ones i've seen smoke like this do it from start up to full load. Check your air filter. When I get one like this, it's fun to put it on the dyno, get the customer and pull the filter out while it's loaded. The filter doesn't look full, but with out it, no smoke and when a new one is installed, no smoke.
HTH

 

[wsucougarx]

Outstanding guys! Thank you for your expertise. Merry Christmas

 

[dburt]

On mid-80's to mid-90's pickup diesels, white with lack of power meant a clogged fuel filter.

 

[wsucougarx]

ok gents, I just had a duh moment. Went out today to get all the snow off the cab of the truck b/c its starting to rain. The snow mixed w/rain...very heavy. Didn't want it to rip the canvas. Anyways as I started to broom off the snow then it dawned on me. I didn't wipe the snow away from the air intake mushroom yesterday Hmm, lack of air probably caused this brown exhaust. Okay at least I did learn something about exhaust color

 

[WillWagner]

A wet air filter element will cause issues too, better check it!

On mid-80's to mid-90's pickup diesels, white with lack of power meant a clogged fuel filter.

A bunch of restriction will actually cause an air in fuel symptom. The fuel will be pulled apart as it is passed through the filter and cause white smoke due to low pressure.

 

[wsucougarx]

OK, so I guess it's my turn to be the TM police. Fully described in the -34 TM if I remember correctly.

Hey you must be pinch hitting for Doghead

 

[mdog]

I don't know about anyone else but I would never take a dirty air filter off any engine of mine while it was running. Or advise anyone else to.

 

[mbwarner]

WSU, I tip my hat to you for owning that one. Particularly since I did the same thing last weekend.

I wonder what the -10 says about snow packed around the air intake. Mayhaps someone will ring in with that answer...

Are you all having fun over there yet, with the weather? We've got near two feet of snow over here in the Walla Walla Valley, which is darn rare.

Stay safe.

 

[WillWagner]

I don't know about anyone else but I would never take a dirty air filter off any engine of mine while it was running. Or advise anyone else to.

Why? Ever done it?

 

[mdog]

I've taken plenty of dirty air filters off of stopped engines and there is enough dirt around the gasket and housing to be plenty bad for the engine. If the engine is running a lot of dirt will be drawn into the engine. It may not ruin the engine but it is not good for it either. I have never seen a manual suggest doing it that way. I have seen engines ruined in one afternoon from dirty air bypassing the filter due to a hole in the intake pipe. I'm more picky about air filters than any other item on an engine. I have refused to buy a filter because I didn't like the look of the box it was in. If it looks like it had been dropped i get suspious and check it closer. Maybe I overreact. I don't mean any disrespect to anyone doing differently but I would not do it if I thought there was any dirt in the area that could be drawn in.

 

[mdog]

After I wrote the above post I realized I was thinking about farm equiopment the whole time I was writing it. With trucks it would be much less of an issue but still not a recommended idea.

 

[saddamsnightmare]

December 26th, 2008.

Gents:

To keep snow and rain out of the mushroom, and hence the air filter, pull the Army field Modification of fitting a 4" exhaust elbow (I think the diameter's right, but measure if in doubt) fitted to the air cleaner intake and turned upwards, with the mushroom fitted on the end. End of snow clogs, Ice clogs, or water getting into your filter element, and if you do it right, it increases your fording depth by a like amount.....

Someone's got pictures somewhere on here of the field mods indicated above....

Happy New Years,

Sincerely,

Kyle F. McGrogan

N.B. The icon annexed of "Saddam's Nightmare" shows the field mod elbow applied to the air intake, a very cheap and easy way in snowy and/or dusty areas of keeping your air intake mushroom clean. These were Field applied modifications to most deuces, not noted in the TM's I believe. One could have the elbow bent special out of heavy tailpipe stock and extend it if need be up almost to the level of the stack, although you would then need to make a support bracket or clamp to connect it to the stack ala fording kit dwgs for better support. The fording kit brings the slobber pipe vent up to this level also.....

 

[Firefighter294]

Pictures stolen from cranetruck

Note air cleaner

 

[cranetruck]

_Black, not quite enouge air to complete the combustion process...the black is soot, excessive black anyway, the multi's like to run that way
....

I have a problem with the last comment...mine idles with a slight haze and runs virtually smokeless on the highway. The multifuel hypercycle is an uncommonly efficient combustion process and quiet to boot.

(Looking for something else and ran into this old post)

 

[hklvette]

I have a problem with the last comment...mine idles with a slight haze and runs virtually smokeless on the highway. The multifuel hypercycle is an uncommonly efficient combustion process and quiet to boot.

(Looking for something else and ran into this old post)

agreed on all counts. I believe the haze is called "slobber" or "wet stacking"