Complained of coolant now leaking. tests were done. pressure testing was completed and no signs of coolant were found. a dye was put into the coolant to see if it is leaking into the heads. I have taken the truck back to the dealer. they are now more confused. they say that they couldn't really tell if there was coolant in the cylinders, BUT!!!!! the look on there faces told me different. they are keeping the truck and are talking to tech support. they want to replace some cooler. they say it may be malfunctioning and dumping coolant into the exhaust... I've never heard that before. and then they are going to replace the head gaskets next. still they say the fuel leak issue is not connected. I disagree based on what problems the LB7 had with injectors failing and leaking. this caused an over heat and over pressurization which caused failed head gaskets. these duramax engines are running on a peak curve for power/fuel economy and emissions. if just one cylinder is not preforming properly as in no fuel to burn I can see if causing a back issue with the return exhaust and over heating. now I have not seen the needle move up but they are not what I would call perfect gauges.