Flushing coolant system. Best way?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Geotrash

Dave
Supporting Member
Joined
Feb 16, 2018
Posts
5,490
Reaction score
12,982
Location
Richmond, VA
I've had to replace the coolant in my Yukons a number of times for various jobs including cam swaps, new radiator, coolant tees, etc. I never had any problems with air in the system or anything else. Modern coolants are remarkable in their protective properties, and I've never seen any sludge or corrosion debris in any of my cars with modern cooling systems, even after hundreds of thousands of miles. I say put new 50/50 Dexcool in it, and send it. No need to flush. I'd be worried about residual flushing chemicals remaining in the system.
 

me88

Member
Joined
Nov 10, 2021
Posts
97
Reaction score
92
Location
Germany
When I changed the coolant in mine, I just took off the lower hose at the radiator and let it drain out. The service manual says there is a drain plug on the engine block, but I could not find it. The whole system is supposed to take about 17 quarts, and almost all of it came out if I remember correctly. Then I refilled it with a coolant with GM spec 6277M and bled the system which was not too difficult.

It is a very messy job though, make sure you have a kiddie pool or something similarly shaped to put under there to catch all the liquid.
 
OP
OP
O

optimusprime

Full Access Member
Joined
Jul 15, 2016
Posts
104
Reaction score
25
Top