Northstar Engines and System Technical Discussion Discussion, "Flush" coolant? in Cadillac Engine Technical Discussion; I have searched through 6 pages under "coolant" and have not seen this procedure addressed: Should I do the coolant ...
I have searched through 6 pages under "coolant" and have not seen this procedure addressed: Should I do the coolant change while running the car and pouring water from a hose into the radiator while simultaneously draining it? At the same time the heater would be on to get old fluid out of there. Also, should I remove the thermostat at some point in the draining process?
What I have seen on the Forum seems to say that draining coolant from the lower radiator hose suffices.
There are at least two reasons why I simply pull a hose and drain as much as possible and refill with fresh antifreeze 50/50 mixed with distilled water. Don't forget the coolant supplement tabs.
One has to do with the mineral and chemical content of my tap water which is an unknown. And two is introducing straight water in there will almost guarantee to lose control of the desired 50/50 antifreeze mixture.
Mix coolant in 50/50 ratio. Drain radiator and block drains if equiped. Fill with new coolant. Drive 200 miles. Repeat. Northstars are very corrosion sensitive. If you are sludged up then keep changing until it is gone. On the later cars without block drains you will need a refractometer to regain coolant system 50/50. This is because you cant get half out.
Thanks for the advice, fellows. I will simply drain and not "flush".
One thing though, I would not be adding water to a hot engine by using the hose system. The engine would be at normal temp, I think, since the fluid level is continually held at the proper level.
Anyway, thanks for taking the time to write.