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Discussion Starter · #1 ·
i have been noticing at night, when sitting at a redlight, smoke coming from the back of my truck. the only way i can see it is if a car is behind me, and i can see it with their headlights. my truck has about 8600 miles on it now, but i noticed this since day 1. i thought it was just breaking in or something. but the truck has plenty of power so what gives? is anyone else seen this or heard of it? should i take it to the dealer and let them look at it? Thank you in advance!
 

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They all do it. You only see it at night cause of the head lights behind you
 

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Blue smoke is oil burning. I guess that would make sense, since it is a diesel! I don't know though...
 

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Discussion Starter · #4 ·
i thought so but it is pretty thick, never saw it in my ole ferd, 7.3?
 

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Any idea how your injectors are doing? Have you checked balance rates?
 

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I never saw the smoke you are talking about on my LB7 but my LLY has done it since day one. I think it is normal since I have heard a lot of people talk about the same thing.
 

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Discussion Starter · #8 ·
how do you check balance rates and what are they?
 

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I think that it's normal to see a little blue smoke when a diesel is cold. Used to see blue smoke all the time from the diesel tractors when they were cold. Also, it is currently about -20C up where I am, and all the diesel trucks smoke a little blue, not just the Duramax.
 

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You'll notice a very light blue color smoke when your engine is cold, or possibly if you've been idling for a long time. Very light blue smoke is caused by cool cylinder walls, causing some of the fuel to condense and not burn properly. White smoke indicates a cool combustion chamber as well, but in addition an over abundance of fuel (i.e. possible leaking fuel injector).

It is possible to see light blue smoke upon cold engine startup even at high outside temperatures, again this is due to the fact the combustion chamber walls are cool and fuel can condense here. At higher outside air temperatures the light blue smoke should cease very soon after startup, where with cold outside air temperatures the light blue smoke can continue for several minutes.

Dark blue smoke on the other hand is bad, that could very well be engine oil being burned and should be checked by your dealer.

p.s. burning oil could be considered normal as diesels are sometimes referred to as "oil burners" due to the fuel we burn, however actually burning engine oil is bad. I think the reference was using this slang term.
 
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