Duramax Blue Smoke

[letkel]

Bought a used 2003 Chev 2500 HD, with Duramax,Allison, with 46000 KM(30000 miles)on it.Going down a fairly steep,slippery,winding road from a ski resort, in 4wdH,with the Tow/Haul mode ENGAGED, with the foot off the accelerator and the engine holding down the speed to about 40-50 KM/Hr, or about 30 MPH, when gently or abruptly pressing the accelerator on straight sections, a considerable amount of blue smoke blows from the exhaust, not just a puff, but for a considerable distance, before it cleared up. The engine had been properly warmed up, the ambient temp was about -10 C or +15 F, and the altitude about 4500 Ft. I am concerned, as this is my first diesel, and not familiar with driveability of a chev diesel, had not noticed anything unusual in my first 100 miles of city and Hwy driving. What could be the problem, what tests could be performed to isolate the problem.Appreciate any constructive suggestions, as to further selftests or dealer tests required.The vehicle had been fresh prepped by the dealer with oilchange (15-40),fuel filter change and airfilters changed

[More Power]

This may be a variation of normal.

If you had had an exhaust temperature gauge, you would have seen your EGT at nearly zero. It takes temperature to efficiently burn the diesel fuel, and long downhill grades in cool temperatures can bring the combustion temp below that necessary to properly combust diesel fuel.

Now, if you were seeing blue smoke at other times, you could have an issue to deal with. But, I think (based on what you're reporting) that you don't have a problem.

MP