Hey all.
So after having my cooling system flushed, blowing my water pump, and installing a new one and having it professionally reflushed and STILL getting that thick brown gunk back, I've decided to try a VERY thorough method of flushing out the cooling system.

First I will try to flush and back flush every component (radiator, engine block, heater core). After that, I am thinking of hooking it all back up and running some strong cooling system cleaner through the engine, then filling with water and draining a few times.

Next, I am thinking of running on pure water from about 3 days to a week (when it gets warmer out), draining and filling it every day in order to get whatever gunk might be left out of the system, maybe even more cleaner.

So my question, is there a better, less stressful way to get rid of all this junk? I want to be running green antifreeze. Also, is running on water, even for a few days, a bad idea? And should I leave the thermostat in or take it out?

Sorry for having such a long first post.
Thanks!

sounds like the orange and green coolant got mixed in your system, it tends to form that kind of gunk that plugs things up

you may want to consider replacing the radiator and heater core

new rad

Running strait water won't hurt anything. It actually has better heat exchange properties than antifreeze. A lot of people down here in florida run strait water.

Why would it be the radiator if aluminum doesn't rust?

Rusty brown coolant doesn't happen overnight. Flush and drain the system well, re-fill with the proper mix and check coolant frequently. When the bright green/yellow color starts to fade, drain/flush/re-fill again. Straight water in a cast iron motor is not recommended and provides virtually zero pump lube.

Ahh I knew there was a reason I didn't want to do that. Thank you.

Also, the coolant in the reservoir is green, but the rest of the system is brown. So it appears that the reservoir is just an overflow tank, so why does it need to be filled to a certain amount?

If its like chocolate milk. It might be bars stop leak. That carp is nasty and fu#ks up your hole cooling. I had a truck with it a sold it. Now a cupply of things. Runing water is ok for a bit cause antifreezes will keep your water pump lubed and make sure its hotter then 30 or 40out side. No thermostat will just take longer for the jeep to heat up. And there is no really easy way to get all that crap out. And the last thing is if u have a high mileage u might break some type of corrosion build up loose in a water jacket so don't use really high pressure. And good luck.

Sounds like your rad cap may be bad. The rad cap has 2 valves and both must function correctly. As the cooling system heats up/pressurizes, the rad cap releases some coolant/pressure to the bottle. As the system cools (overnight), the rad cap allows coolant to return from the bottle to the radiator. If the rad cap is functioning correctly AND there are no leaks elsewhere, coolant in the bottle should be the same color as coolant in the radiator.

I back flush my system maybe around 7 times.....50 miles later, coolant turned brown.

Bite the bullet and got a new radiator (around $65)....green is all i see now.

Why would a aluminum/plastic or copper/brass radiator make coolant turn rusty brown? The only thing in the cooling system that rusts is the block/head.

the sludge probably isn't rust, it's the by-product of mixing the 2 types of coolant or way too much stop-leak

Just did my system on my jeep, as the radiator was leaky/busted. The coolant that came out was orangish brown like that, and i know it had stop leak in it previously. But i'm in process of replacing old beat rad and new hoses. Also flushed it. Will be replacing with the bright green coolant . Mine wasn't that brown though. That looks like southern clay water lulz.

Mine doesn't have that swirly look to it. Plus I think I'm leaking coolant. I can always go in and give a big splash of coolant every time I open the radiator. So a new rad is probably the way to go.