How to flush coolant before replacing entire cooling system

connor grimes

Oct 24, 2018
Los Angeles
my radiator needs to be replaced so i'm using this as a reason to update cooling system components. plans are
water pump
serp belt
fan clutch all new hoses and clamps

I had to use K-Seal for a temporary fix for my radiator so i want to make sure i get all that crap out of the heater core and engine block so when i put the new parts on theres zero chance of contamination of the k seal gunk/old coolant getting into the new parts.
if im replacing everything should i just remove all parts then flush engine block and heater core via garden hose? then install new parts? run once with distilled water to get tap water out then replace with 50/50 coolant ? thanks guys


TJ Enthusiast
Aug 28, 2018
Wheeling, WV
I always use a garden hose to flush the system, then reverse my shop vac and blow air through the system to get all the water out.

Mr. Bills

TJ Enthusiast
Nov 24, 2017
Area Code 530
If you don't have a shop vac or a source of compressed air, then just flush with a garden hose, drain as much as possible and don't worry about the tap water left in the water jackets. There won't be much.

Unless the mineral content of your local tap water is extremely high, the concentration of minerals remaining after adding coolant and distilled water at the end of the job will be so small as to be of no concern.