Switched to a coolant flush machine and found a disaster

I've been doing coolant flushes the old way for years, using a bucket and a hose. Last month I finally rented one of those machines that cyclically flushes the system. Hooked it up to a 2012 Freightliner that had been running fine, just due for maintenance. After the cycle finished, I drained out what looked like muddy water mixed with sand. The machine pushed out chunks of scale I never would have gotten with gravity. Turns out the system had been slowly building up crap for over 100k miles. Learned my lesson the hard way, now I'm wondering how many other trucks I've serviced that are sitting with the same issue. Has anyone else seen this kind of buildup in newer trucks that looked clean from the outside?

2 comments

2 Comments

the_jennifer1mo ago

Used to think those flush machines were just a way to upsell customers on something they didn't need. Then I borrowed my buddy's and ran it on a 2015 Peterbilt that I swore was clean. Mud and chunks came out for a solid five minutes after the initial drain. Totally changed my mind, now I'm slowly buying my own setup. You never really know what's hiding in there until you give it a good forced flush.

jade2711mo ago

That line about "mud and chunks" is exactly what got me, @the_jennifer. I had the same exact thing happen on a 2018 International that looked spotless on the dipstick. The machine shook loose stuff I swear had been sitting in there since the truck was built. Makes me wonder if the old gravity method is basically just a gamble. You're basically just hoping the worst of it settles somewhere you can drain it, but a lot of that crap just stays put. That forced flush really shows you how much junk builds up in the nooks and crannies. It's eye opening once you see it with your own eyes.