View Single Post
      08-30-2016, 06:24 AM   #63
Major General

Drives: 08 E90 M3, 99 E36 M3 Turbo
Join Date: Feb 2011
Location: Concord, NH

iTrader: (3)

Originally Posted by M3amigos View Post
I'm thinking of doing a coolant change soon. I'm not sure if I want to mess with the engine drain plugs, and I am contemplating an alternate method of flushing the whole system. Rather than draining and refilling with new coolant and wasting it, what if I drained and refilled with distilled water until it came out clear, then on the last fill use coolant only. I read the radiator plug drains about 1 gallon, so 1 fill of straight coolant would result about 70/30 mix. I'm in FL so I'm thinking the higher ratio may keep the car running cooler. Any thoughts?
Not sure it would come out clear, but you would certainly dilute it a lot by successive partial draining. Seems like more of a pain to do a worse job to me but if it's easier for you then it is at least better than just draining the radiator once and refilling. The blockdrain method is messy but best. Your method requires driving the car between each partial drain to get it hot so the thermostat opens. Then you need to wait for it to cool. And you would want to do this 4-6 times.