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cloud of blue exhaust smoke on startup
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Author:  chrispitude [ Tue Mar 25, 2008 7:55 am ]
Post subject:  cloud of blue exhaust smoke on startup
Hi folks,

Yesterday I happened to be outside when my wife started up the CRD to go to work, and saw a decent cloud of blue exhaust smoke on startup. I noticed this a few times over the winter too, but I chalked it up to the really cold temperatures and longer cranking times dumping more unburnt fuel into the cylinders. This time, the engine caught quickly and it still happened. On a turbo gasser, it's a sign that oil is leaking through the turbocharger seals. Is this normal on these vehicles? The turbocharger was replaced back in November. I'm really hoping something's not wrong with it already.

- Chris
Author:  05infernoCRDL [ Tue Mar 25, 2008 8:17 am ]
Post subject: 
Chris,

from what i have been reading blue smoke on start up i not bad on initial
start up. if you are cruising and seeing blue smoke then it is bad. diesel is
an oil, and the first few seconds all of it is not being burnt if they cylinders
are not hot enough.

i know the Mercedes i had on start up would puff a little bit of blue smoke,
and the turbo on that was fine.
Author:  Uffe [ Tue Mar 25, 2008 8:49 am ]
Post subject: 
I get a neckwind most of the time I start my CRD up from home. Always blue/whiteish smoke at startup. It is either more visible or there is actually more when it is wet out.

When I saw it the first time I though "oh no, head gasket!" but it's normal and does it every time when it is cold out. When the engine is hot and I start her up there is no problem.

My experience only :)
Author:  Joe Romas [ Tue Mar 25, 2008 8:56 am ]
Post subject: 
I think the blue smoke on a cold start is because the glow plugs don't stay on long enough before starting the engine. Mine light is on for just a second or two :wink:
Author:  dog_party [ Tue Mar 25, 2008 9:48 am ]
Post subject: 
Does your wife crank right through the ignition sequence (plug key in and crank all the way to starter)? Or does she "Wait To Start" like the old diesels "made" you do.
Author:  gmctd [ Tue Mar 25, 2008 10:31 am ]
Post subject: 
Blue smoke at start-up on those other engines is caused by worn intake valve-stem seals, and piston rings, where high intake vacuum pulls the oil into cylinders not intended for oil consumption = blue smoke

Diesel engines do not suffer from copious levels of intake vacuum, as they do, so even if there happens to be raw oil in the intake, it is not ingested in sufficient quantity to make smoke in an engine that comsumes raw oil as fuel - compressor-side leaks are rare, again because no high intake vacuum to pull the oil thru the seal (Diesel turbochargers use labyrinthine\centrifugal seals, which would leak copiously in one of those engines): rather, the intake is usually under some pressure, which those in the know term "Boost" - Diesels do not suffer from oil leaks thru the piston rings, again because no vacuum on the intake stroke to pull the oil passed the rings - which brings up the reason they wear quickly, while Diesel engines wear slowly: raw gasoline fuel on each intake stroke washes the lubricant from the cylinder walls, continuing the process on the compression stroke = wear - Diesel fuel, also a lubricant, is injected in the combustion cycle at the top of the compression stroke: pistons\rings never encounter vast areas of depleted lubricant on the cylinder walls = million mile engines

Back to the blue vapor on startup: good ole #2 will blow white vapor on cold startup - no tellin' what color rancid McDonald's french fry\mcnugget grease, and those other substitutes, will burn, but it shore ain't gonna be white - knowhuttimean, jellybean?...............
Author:  gmctd [ Tue Mar 25, 2008 11:19 am ]
Post subject: 
Short treatise on blue smoke -

Those other engines run by ingesting gasoline and air on the intake stroke at a ratio of 14 air to 1 fuel, 14:1, termed stoichiometric, from the Greek word for 14 - street lingo is 'stoke', from stoich - after the fuel has been rapidly oxidized, which street people call combustion, there is absolutely no remaining oxygen in the combustion chamber - fuel and oxygen are terminally depleted, flame out, only hot gasses under high pressure remaining -

But, wait! What about that quantity of oil vacuumed past the worn rings and seals, still hanging about in the cc? Oil can be used as fuel, right? Spark ignited the gasoline, so combustion temps are hot enuff to ignite the oil - why doesn't it ignite and burn, leaving no blue smoke, which indicates unburned (unignited) fuel?

Stoke, folks - stoich - 14:1 - stoichiometric oxygen\fuel ratio - all the oxygen is gone, depleted when the gasoline ignited - any remaining fuel is at\near combustion temperature, but no way to oxidize it, so you get hot raw oil vapors = blue smoke - as it would have been too rich for the combustion event, you get the blue

Why does the gasoline get all the oxygen, and not some of the oil? Viscosity\volatility, flammability.

Black smoke is where the fuel was combusting, but flame went out due to lack of oxygen - the black is soot particles in the remaining raw fuel vapors - you can see that when the engine is running rich, with greater than 1:gasoline to only 14:air

White smoke is where the fuel was not quite up to combustion temp, couldn't ignite but the misted fuel was raised above the vapor temp, so you get raw fuel in vapor form - can be dangerous because that will ignite easier than misted fuel when exposed to the oxidation agent\component in atmospheric gasses at the end of your tailpipe - backer up to a campfire, see what I mean, eh?

For an excellent Science 101 experiment to demonstrate the concept, next time yer in yer dominant male mode, demonstrating prowess by charcoaling some dead animal flesh (or veggie-bobs, for you girly men), take the lighter fluid, squirt it on the barely glowing coals, noting the resultant white vapors emanating as the excess fuel refuses to ignite - that's cold-start - after coals are fiery red-hot, again squirt the lighter fluid into the conflagration, noting how the fire\flames immediately shoot up, but with copious quantities of black smoke - that's rich running, where the excess fuel was ignited but not enuff oxygen to sustain combustion, so you get sooty raw fuel vapors

Thus, and so..................
Author:  retmil46 [ Tue Mar 25, 2008 11:50 am ]
Post subject: 
A puff on startup of whatever flavor smoke isn't necessarily a problem - if it's still throwing out the same color smoke several minutes AFTER startup or after it's warmed up, that would be worth investigating. FSM has a chart listing possible causes of different color smoke in other-than-normal circumstances.
Author:  MrMopar64 [ Tue Mar 25, 2008 1:30 pm ]
Post subject: 
I would put my diagnosis on it being just a calibration issue. Because of engine to engine variability, some do it more than others. If timing was advanced a few more degrees during the start with only 1 pilot instead of 2 and another 20 bar of rail pressure it probably wouldn't do it. Also some more post glow would help but then you compromise the longevity of the GLP in the KJ engine.

So, in a nut shell, no worries.
Author:  chrispitude [ Tue Mar 25, 2008 4:54 pm ]
Post subject: 
It's hard to share all my gasser turbo past experiences where I see that cloud on startup and my stomach sinks... Thanks guys! :) This forum is great.

- Chris
Author:  warp2diesel [ Tue Mar 25, 2008 6:06 pm ]
Post subject:  An answer for the blue puff
One thing that can be done to reduce the initial blue puff of smoke is to use a fuel with a higher CETAINE; I fueled up on my way back from a job in LaPorte, IN and went to place that sends money to Hugo Chavez called CITGO because they had a cheap price of $3.99 Vs $4.07. When I did a start on the following morning, I got the Blue Puff. Most of the time I am in Indianna I go to Pilot and buy B-10 that has a higher cetaine, no blue puff. Our CRDs were designed to run on the 55 cetaine fuel not the crap that is being sold in the pumps. A lot of the older big rigs would have issues with 55 cetaine so they lobbied for 45 cetaine instead so they would not need to have their injection systems re timed.
When I worked for the Perkins distributor, we had to set the timing ahead to compensate for the lousy cetaine to get rid of the Blue Roll warm up smoke. The GM 6.5L Turbo and other GM engines had a wax element with a heater to advance the timing for warm up to get rid of the Blue Roll caused by lousy low cetaine. When I had my old Perkins 354 Turbo, I had to buy a Ferrite Instruments timing light attachment and use it to set the timing instead of the line up the marks method to get rid of the Blue Roll I had until it was warmed up. After a lot of trial and error, I got the timing to a point where I had good power and no more Blue Roll, just the Blue Puff. I traded that beast for my CRD a year ago.
Other than shopping around for good fuel and installing a lift pump, there is little we can do for the Blue Puff. Since I have the stock F-37 flash and a lift pump, I suspect in my case I am being Blue Puff punished for buying #2 Dino from the place that sends money to Hugh Chavez.

Steve
Author:  dkenny [ Tue Mar 25, 2008 9:50 pm ]
Post subject: 
blue smoke usually means it burnin oil not fuel..for some reason.

for others wondering about burning grease/biodiesel..
I have a DD8.2L tubro ...without glow plugs that puts on WHITE smoke when it cold, not blue..

so its burning something else besides diesel..I would guess oil

how many miles on the engine?


-dkenny
Author:  warp2diesel [ Tue Mar 25, 2008 10:01 pm ]
Post subject:  Incomplete Diesel Combustion
Can appear to be white or blue.

A lot depends on the light and the angle it is viewed from.

My CRD has 28K and does not use any oil, besides diesel fuel is oil.

Go by the dipstick when you check for oil consumption, but, do it first thing in the morning and make sure you are parked in the same place every time.


Steve
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