Diesel Injector Failure Symptoms?

[TBow]

I have an '07 Duramax. GM had been having problems with their injectors on previous years' Duramax injectors, so as to extend the warranty on the injectors to 230,000 km on some years and 300,000 km on other years. My '07 only has the 160,000 km Drive Train Warranty covering the injectors. I currently have 150,000 km on the truck.

My concern is that if the injectors are going to fail, then replacement could run $3K to $4K. It is reasonable then for me to hope to have them replaced under the Drive Train Warranty before it expires, if in fact the injectors require replacement. I talked to the service manager at the local dealership about having them tested just prior to hitting the 160K mark. He indicated the cost was about $250 to check them, but I'm unsure as to how much faith to hold in a test that may not involve the removal of the injectors and putting therm on a test jig with pressure guages, etc.

I have noticed my fuel mileage slipping slightly from when I purchased it last fall, but then colder weather can affect the mileage and I've since put on a truck cap which translates into additional weight and wind resistance. So those factors may contribute to the mileage variations.

When I pull onto a multi-lane highway and accelerate from the ramp, I get a few seconds of black smoke signalling carbon, or unburnt fuel. I usually don't work the Duramax all that hard, so I've been told to expect carboning.

I was told that the '07 Duramax had a lower voltage to the injectors than previous the 2000 to 2006 Duramaxs, and my belief is that the higher voltages may have contributed to the high rate of injector failures on earler years. Is that true? Did GM finally get it right by '07?

Are there any other symptoms that might signal early signs of injector fatigue, and are there any particular tests that I should be requesting from the dealership prior to the warranty expring?

TBow

Edited May 29, 2011 by TBow