nvsierra04
New member
I have a 2004 Sierra (Z71) has 225,000 on it. Anytime the truck sits for a couple hours or more it has a big cloud of white smoke come out tail pipe. It goes away and seems to run good. Been told it sounds like valve seals, but also since its high mileage and burning a quart about 1000 miles its probably best to replace motor. Need some good solid advice. Rebuilts running between 3K and 4K.