WHat does lots of black smoke mean? - Page 2 - PeachParts Mercedes-Benz Forum

patbob · #16 01-30-2008, 01:58 PM

Quote:

Originally Posted by ForcedInduction

Unburnt fuel. Clogged air filter, valve adjustment past due, bad injector(s), stuck turbo, low compression, etc. Anything that will cause the engine to be starved of enough air to complete combustion.

So what.. nobody's going to suggest that the air filter is full of nuts?

OK, I'll suggest it.. air intake clogged with mouse nest or squirrel nut repository.

Good question to ask them is why they stopped driving it. Most people don't stop driving good running cars.

vstech · #17 01-30-2008, 02:24 PM

Quote:

Originally Posted by P.E.Haiges

Forced,

Wrong again. Its lean mixtures that cause high exhaust gas temperatures (EGT).

Gasoline piston engine airplanes have carburators that have manually adjustable fuel mixtures. The mixture is leaned out for maximum power an economy. BUT the pilot watches the EGT gage so as not to not make the mixture too lean that will make the EGT too high and damage the engine.

Small 2-cycle engines (chain saws, weed whackers etc) can be tuned for maximum engine speed by leaning the mixture but if its too lean, the engine will run too hot and may sieze (don't ask me how I know this). The proper way to adjust the fuel mixture on these engines is to use a tachometer and only adjust the fuel mixture for the maximum engine speed specified by the manufacturer.

I know it seems logical that the more fuel, the higher the EGT. But that's not the way it works on the real world.

P E H

um, no.
on a diesel engine, the air fuel ratio is ALWAYS lean.
I was taught this here on this forum.
gasoline formulas and diesel formulas do not mix.

winmutt · #18 01-30-2008, 02:58 PM

Lots of algae will cause black smoke. Dump the fuel and change the filters and try some biocide. Verify new air filter and check the turbo while you are in there.

P.E.Haiges · #19 01-30-2008, 03:10 PM

vstech,

"On a Diesel engine, the air fuel mixture is always lean".

Not true.

Diesel engines do run lean at idle because there is no air restriction and little fuel is injected. But at full load Diesels are running a richer mixure for more power, thus they usually smoke more at full load.

With the small amount of fuel injected at idle, there is no problem of high EGT.

P E H

P.E.Haiges · #20 01-30-2008, 03:47 PM

winmut,

Algae will only cause black smoke if they grow in the air filter.

Its a fungus that grows in the fuel system and that won't cause black smoke. Just the opposite, it will block fuel form getting thru the tank strainer and fuel filters and will make less or no smoke.

U suggest dumping the fuel. Depending how much is in the tank, that could be a very expensive solution at $3+ a gallon when a biocide will solve the problem.

P E H

jaoneill · #21 01-30-2008, 07:31 PM

Originally Posted by ForcedInduction
"Unburnt fuel. Clogged air filter, valve adjustment past due, bad injector(s), stuck turbo, low compression, etc. Anything that will cause the engine to be starved of enough air to complete combustion."

To also include a critter nest in the air intake.......

Brian Carlton · #22 01-30-2008, 09:20 PM

Quote:

Originally Posted by P.E.Haiges

vstech,

"On a Diesel engine, the air fuel mixture is always lean".

Not true.

Diesel engines do run lean at idle because there is no air restriction and little fuel is injected. But at full load Diesels are running a richer mixure for more power, thus they usually smoke more at full load.

With the small amount of fuel injected at idle, there is no problem of high EGT.

P E H

Sorry Paul, John is correct on this one.

All diesels run with excess air under all conditions. If the engine is improperly tuned or is mechanically unsound and cannot deliver sufficient air, the engine will smoke due to an overly rich condition. However, this is never by design.

Lance is also correct regarding excess fuel. It drives the EGT's way up on a diesel. Whether it will cause damage under part load conditions is subject to debate.

minimike1 · #23 01-30-2008, 09:25 PM

Hmm. white smoke= we have a pope! Black smoke=No pope yet. Lots of black smoke, we have no idea of who will be pope yet!

P.E.Haiges · #24 01-30-2008, 10:40 PM

Brian,

Then how come all my Diesel engines spew black smoke when they are pushed hard if they always run lean? I don't mean only MB Diesels, my truck, and tractors all smoke black when they are running under full load.

P E H

Brian Carlton · #25 01-30-2008, 10:43 PM

Quote:

Originally Posted by P.E.Haiges

Brian,

Then how come all my Diesel engines spew black smoke when they are pushed hard if they always run lean? I don't mean only MB Diesels, my truck, and tractors all smoke black when they are running under full load.

P E H

Black smoke indicates excessive fuel...........and also indicates a problem with the engine because it's not getting sufficient air. This is not by design, however.........many older diesels suffer the same malady.

#26 01-30-2008, 11:29 PM

Quote:

Originally Posted by P.E.Haiges

Wrong again. Its lean mixtures that cause high exhaust gas temperatures (EGT).

Incorrect. You are thinking as if this is a gas engine. Diesels always run lean unless they are smoking black. For diesels, lean is cool and rich is hot.

winmutt · #27 01-31-2008, 10:11 AM

Quote:

Originally Posted by P.E.Haiges

winmut,

Algae will only cause black smoke if they grow in the air filter.

Its a fungus that grows in the fuel system and that won't cause black smoke. Just the opposite, it will block fuel form getting thru the tank strainer and fuel filters and will make less or no smoke.

U suggest dumping the fuel. Depending how much is in the tank, that could be a very expensive solution at $3+ a gallon when a biocide will solve the problem.

P E H

Sorry algae WILL cause incomplete combustion in severe cases. Been there done that.

vstech · #28 01-31-2008, 12:15 PM

Quote:

Originally Posted by P.E.Haiges

Brian,

Then how come all my Diesel engines spew black smoke when they are pushed hard if they always run lean? I don't mean only MB Diesels, my truck, and tractors all smoke black when they are running under full load.

P E H

because when they are pushed hard, the fuel enrichment device on your truck adds too much fuel.

doxland · #29 02-15-2008, 12:37 PM

PE Haiges

These last comments about leaning are Gasoline engine thinking.
Diesels (if in an acceptable running condition) always run in overleaned or beyond full air. There is no excess fuel.

Leaning is Gasoline engine thinking and has no place in Diesel operations except that when they come to the excess fuel condition or poor atomized condition they may have combustion continuing on through the exhaust process and burn fuel while passing the exhaust valve.

Gasoline engines always used to run in an excess fuel condition so as to make combustion commencement reliable and to help control the exhaust temperatures.

babymog · #30 02-15-2008, 12:51 PM

Older diesels didn't have the emissions requirements, so black smoke was not prohibited (to a point).

I agree with others, that the diesel will run lean most of the time, it has all of the air it needs with no throttle on the air supply.

To increase power, you increase heat. To increase heat, you increase fuel. Fuel is air + diesel fuel, the air is already there so you turn up the fuel.

When diesels were allowed to smoke a little, it was common practice to overfuel at full-throttle. Even though the excess fuel isn't burning completely (thus the smoke), it is creating a little more heat = a little more power. You can overfuel to a great degree and get more power, ever watch a tractor pull? Diesels at a drag race? The efficiency isn't there, you're getting less energy per gallon of diesel, but you will get more energy with more fuel to a point. It also will create lots of smoke and too much heat for the engine to last, but it is a cheap and simple way to increase power.