Last month I learned what seems to be a reliable way of getting ALL the old fluid out of a cooling system, quite by accident. I have this old car with unkown history which blew the bypass hose under hard acceleration, and then (obviously) needed a coolant flush/refill.
I've always used this method to try and ensure a complete flush, but this time I'm pretty sure I actually did. I leave a garden hose connected to the kitchen sink faucet running HOT water into the rad, with the heater on and the drain open to equal fill/drain rate. Then just let it run for awhile till the fluid comes out clear.
This time I'm absolutely positive all the old anti-freeze was gone. At one point after about 20 minutes I heard an odd noise and looked outside the garage to see the rad boiling over! Definitely couldn't have been much Prestone left in there! Running at least 214deg.F too I believe, by then.
Seems OK now, probably could use a new radiator/recore, though. Haven't had it on the road enough to determine the actual viability of the cooling system yet.
I've always used this method to try and ensure a complete flush, but this time I'm pretty sure I actually did. I leave a garden hose connected to the kitchen sink faucet running HOT water into the rad, with the heater on and the drain open to equal fill/drain rate. Then just let it run for awhile till the fluid comes out clear.
This time I'm absolutely positive all the old anti-freeze was gone. At one point after about 20 minutes I heard an odd noise and looked outside the garage to see the rad boiling over! Definitely couldn't have been much Prestone left in there! Running at least 214deg.F too I believe, by then.
Seems OK now, probably could use a new radiator/recore, though. Haven't had it on the road enough to determine the actual viability of the cooling system yet.