I have a 2004 lb7 that I just did all 8 injectors and the water pump on. This is a high mileage truck. 400,000. It runs nice but I am using coolant. No puddles under the truck. My oil is spotless. No oil in coolant and I have not one time noticed pressure in my rad hose. When we removed the injectors the cups was rather dirty. We cleaned and reassembled with new injectors but we did not replace any injector cups. I am not a expert on Diesel engines at all. I am just your average handy guy. So after reading a bit it seams the cups can some how affect coolant usage though I am unsure exactly how. When we tore this down our injectors was filthy and one was stuck open and the oil was full of fuel. I have noticed steam or smoke on the right side a few times after shutting down, the same side as the stuck injector. And ideas would be awesome, I would rather not pull heads untill next winter. Thanks.