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Blue/White smoke after long idle time
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Author:  NotPicky [ Wed Nov 30, 2011 12:43 am ]
Post subject:  Blue/White smoke after long idle time

Just noticed that after 20 to 30 min of idle time and then take off, there is a blueish/white smoke that the crd puts out. Its pretty heavy at times. The exhaust will burn your eyes like an old straight piped diesel. I still have the cat. It fades after a block or so. No loss of power or heavy oil consumption. When its cold there is a little puff of light blue then it fades to nothing, just like my other diesels. Has anyone else had this problem. Its happened twice to me now.

Author:  geordi [ Wed Nov 30, 2011 1:33 am ]
Post subject:  Re: Blue/White smoke after long idle time

Your sig indicates that you have a 40hp cheater chip. These CRDs are running too close to the design limits of the stock turbo, and cheater chips just endanger the turbo even further. The blue smoke indicates that you ARE burning oil, I would be concerned about a possible oil leak from the turbo. They are fine with long idling normally, but if the turbo overspeeds, it can put excess wear onto the main bearing, opening out the space internally and allowing the oil to seep past the turbine seal. It doesn't take more than a few drops to make a lot of smoke, so it might not be a huge issue yet. But that leak is there.

If the noise your turbo makes ever changes in any way - Gets louder, whistles all the time, any kind of grinding or high-pitched jingling / scraping noise... Your turbo is dying, and you have MINUTES remaining. If you do not monitor your engine oil level and the leak opens up to any significant flow... Your engine will be OUT of oil in as little as 30 seconds. Up until that point, it's only a turbo. If the oil level drops, your pistons will starve almost instantly and the engine is done.

Author:  NotPicky [ Wed Nov 30, 2011 10:43 am ]
Post subject:  Re: Blue/White smoke after long idle time

Wow doesn't take much to take this little worthless turbo out at 80k. Ill have to pull the down pipe off to see if there is oil residue on the turbine side. The chip hasn't been on there for more than 3000 miles. It wouldn't be a injector failing would it? I know the early duramaxs would smoke a blueish white smoke always at idle if they had a injector failing. Is there a way to do a injector test?

Author:  GreenDieselEngineering [ Wed Nov 30, 2011 10:55 am ]
Post subject:  Re: Blue/White smoke after long idle time

I believe you are experiencing high levels of hydrocarbon emissions after the extended idle. During long idle periods the oxidation catalyst cools off below its 'light-off" temp threshold and it no longer converts much HC. Your fooler chip also is increasing the fuel pressure at idle and you tend to get deeper penetration of the fuel spray that may be hitting the top of the piston or cylinder walls, which leads to greater levels of unburnt hydro carbon chains. This also hurts fuel efficiency and could lead to more fuel dilution in the oil during extended idles.

Once you drive away under some decent load the HC buildup just before and in the catalyst will blow out giving the big cloud. This clears up shortly as the catalyst reaches operating temp and converts the HC.

Author:  NotPicky [ Wed Nov 30, 2011 11:13 am ]
Post subject:  Re: Blue/White smoke after long idle time

So you think its a really rich idle that is getting stored before the cat while the system cools for long periods of time. At idle the egts are 250 degrees. So with the added fuel at idle and low temps it won't do a complete burn. That makes sense. Ill unplug and see if it goes away. If it continues without the cheater chip then what?

Author:  papaindigo [ Wed Nov 30, 2011 11:46 am ]
Post subject:  Re: Blue/White smoke after long idle time

Just curious why are you idling for 20-30 minutes? There is no reason to idle to warm up, won't work on a diesel anyway, and turbo cool down doesn't require that length of time.

Author:  nursecosmo [ Wed Nov 30, 2011 6:17 pm ]
Post subject:  Re: Blue/White smoke after long idle time

What is your coolant temp during this extended idling? If the thermostat isn't up to snuff, you are at risk of cylinder washing or unburnt fuel/oil making it's way into the cat and saturating the matrix.

Author:  NotPicky [ Thu Dec 01, 2011 12:37 am ]
Post subject:  Re: Blue/White smoke after long idle time

papaindigo wrote:
Just curious why are you idling for 20-30 minutes? There is no reason to idle to warm up, won't work on a diesel anyway, and turbo cool down doesn't require that length of time.


Just keeping the heater running. Its not to warm it up, its to keep it warm. Im in it for much of the day.

nursecosmo wrote:
What is your coolant temp during this extended idling? If the thermostat isn't up to snuff, you are at risk of cylinder washing or unburnt fuel/oil making it's way into the cat and saturating the matrix.


Unpluged the chip and it still did the same thing. The temp cools down to the quarter mark.

Author:  geordi [ Thu Dec 01, 2011 12:57 am ]
Post subject:  Re: Blue/White smoke after long idle time

Thermostat is toast then. Consider the in-line thermo as an option for replacement, rather than the factory mess at the moment. Kap's very well designed replacement housings for the factory aren't ready yet, as he is still in transit / getting set up in Oz at his new digs.

1/4 on the temp gauge is too low, your viscous heater will be cycling on potentially and wasting even more fuel... Or your heat will just be poor. With a good thermo, the inside of your CRD could be a sauna. But I dispute the "cylinder washing" nonsense. Bad combustion, maybe. But fuel into the oil? If that were the case, our dipsticks would be drooling fuel out the top, especially when I used my CRD as a hotel and idled it for 8 HOURS continuously to run the AC in the summer. EGT was (as you'd expect) down to 350 before the turbo. Oil level was constant, and no smoke either.

Carb-loading a cold cat could certainly lead to a nice big cloud of BLACK smoke when it finally combusts, but OIL is the only thing I know of that burns BLUE. Anti-freeze smoke is white, so there are your choices. Ya got blue smoke? You have an oil leak, somewhere. A little will go a long way in making smoke in the exhaust system, b/c nothing else is consuming the oil - it all goes to smoke.

Author:  nursecosmo [ Thu Dec 01, 2011 2:31 am ]
Post subject:  Re: Blue/White smoke after long idle time

geordi wrote:
Thermostat is toast then. Consider the in-line thermo as an option for replacement, rather than the factory mess at the moment. Kap's very well designed replacement housings for the factory aren't ready yet, as he is still in transit / getting set up in Oz at his new digs.

1/4 on the temp gauge is too low, your viscous heater will be cycling on potentially and wasting even more fuel... Or your heat will just be poor. With a good thermo, the inside of your CRD could be a sauna. But I dispute the "cylinder washing" nonsense. Bad combustion, maybe. But fuel into the oil? If that were the case, our dipsticks would be drooling fuel out the top, especially when I used my CRD as a hotel and idled it for 8 HOURS continuously to run the AC in the summer. EGT was (as you'd expect) down to 350 before the turbo. Oil level was constant, and no smoke either.

Carb-loading a cold cat could certainly lead to a nice big cloud of BLACK smoke when it finally combusts, but OIL is the only thing I know of that burns BLUE. Anti-freeze smoke is white, so there are your choices. Ya got blue smoke? You have an oil leak, somewhere. A little will go a long way in making smoke in the exhaust system, b/c nothing else is consuming the oil - it all goes to smoke.


Respectfully, you are wrong on this one Geordi and is not nonsense. I use "Wet Stacking" and "Cylinder Washing" interchangeably even though they technically are two different conditions but if you have one, you have the other and both do definitely occur in the CRD if the thermostat doesn't keep it warm enough. Mine started doing it pretty bad last winter which convinced me that I had put off replacing the thermostat long enough. It will not cause the dipstick to "drool fuel" but I had a measurable rise on my dipstick over the course of a couple months which motivated me to also change my oil at only 4000 miles. Even though I have a gutted cat, enough unburnt fuel would collect in the cat canister/muffler/exhaust system to make a pretty noticeable whitish/grayish cloud when I'd gun it after sitting for 15 minutes or so (although A supposedly knowledgeable mechanic once called it blue smoke). It was not oil smoke it was unburnt diesel. I've driven and wrenched on enough diesels in my life to know the difference in both color and smell. A new thermostat fixed it. Unburnt diesel (almost) never makes black smoke in a cold engine. That occurs from too rich of a mix in a warm engine. Too many people from the south just don't appreciate how diesels behave in truly cold weather such as is found in Chugwater. The Oxidative Cat which is found in the CRD requires a minimum light off temp of 200C to function and only functions at 30%-50% efficiency at 300C. EGTs do not reach this minimum temp when idling with a non-functioning thermostat in cold weather.

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