Bacteria growth in radiator?

[toximus]

I've also run around 40 gallons of distilled water through the radiator by filling, bringing up to temp, and draining.

 

[04 LJ]

The coolant is Zerex G05 which is pricey stuff so I don't want to waste any more by aimlessly draining and filling again.

If you have NAPA auto parts, they have it on sale for $13.99 a gallon right now. Get another 10% discount on top of that if you spend enough or 5% off with AAA membership.

 

[04 LJ]

Probably just corrosion products. This is mine. Didn't improve much after several chemical flushes.View attachment 97221

That coolant doesn’t look so good.

 

[Steel City 06]

That coolant doesn’t look so good.

That's drained.
You're looking at the sludge sitting there.

It has actually never overheated or even gotten warmer than normal, even when run hard, so at this point I'm ignoring it until I eventually replace the radiator.

Coolant didn't look too cloudy, surprisingly.

 

[Steel City 06]

I've also run around 40 gallons of distilled water through the radiator by filling, bringing up to temp, and draining.

You might try a chemical flush.
I used the Prestone flush on mine and it made somewhat of a difference.

Pour in the bottle, fill with distilled water, and give it an hour long Italian tuneup, including long hill climbs with the pedal floored and some 5000 rpm shifting. The extra heat in the coolant and RPM of the water pump helps to force out deposits versus just letting it idle

 

[Flivver250]

Maybe your jeep has a yeast infection.

 

[04 LJ]

That's drained.
You're looking at the sludge sitting there.

It has actually never overheated or even gotten warmer than normal, even when run hard, so at this point I'm ignoring it until I eventually replace the radiator.

Coolant didn't look too cloudy, surprisingly.

Oh. Wow. Looks like G05 jello then. Def didn’t realize it was drained. I just overhauled my entire cooling system and got a decent deal on a brand new Mopar radiator as part of the process. Rockauto.