I’ve never flushed the coolant on my 08 6.2 Denali since I’ve owned it (5.5 years). Recently the heater hoses busted off and dumped a ton on the ground. I’m going to replace them and the upper/lower rad hoses and thermostat. Do I need to totally drain every last ounce of coolant out or can I just drain the lower hose and add new fluid? If I have to flush the entire system, what’s the best way to do it?
the best way is to let the dealer do it simply because they use a machine that vacuums the entire system out,
other than that just doing it yourself then park it on a slight incline with the nose down or jack up the rear a little, pull the lower radiator hose let drain out, replace the hose and point it nose up a little or jack up the front a little and refill with 50/50 mix. doing this allows all the air out.
my personal recommendation would be to also fill it with water a few times to push all the old coolant out, I also normally throw some radiator flush & water in it as well and drive it a couple days then flush it again.
others may have a different method.
