I've flushed my cooling system several times in the past 2 weeks, I think I'm on my fourth flush. Every time I flush my cooling system with Prestone flush, the water comes out like chocolate milk so I flush it with fresh water till it's clear. If I drive the car with just water (just to circulate and flush any reminants) the water stays clear...but if I add another bottle of flush, the water turns chocolate milk brown again within a couple days or less. We're talking cloudy can't see through brown. At least I know the flush works really well.....

there's no heater core and the radiator is maybe a couple years old.


Is it normal and whatever the flush removes is just normally stuck in there? Or should I continue to flush till there is no more brown with the Prestone flush?

I plan to add coolant back in but not if there's still a bunch of gunk in there.

I'm thinking of going with the Toyota red coolant since I use that with my Camry, so if you have opinions on that I'd be glad to hear those too.


thanks guys!

 

Just use green coolant. You can buy it at Walmart cheaply. SuperTech brand.

 

Is it normal and whatever the flush removes is just normally stuck in there? Or should I continue to flush till there is no more brown............
I plan to add coolant back in but not if there's still a bunch of gunk in there.

I believe the Prestone flush is actually an acid of some sort, so the brown you are seeing is due to the reaction that happens.
You have used MORE than enough of the Prestone flush.
The owner of a radiator shop told me his secret for cleaning the cooling system decades ago: Lestoil to clean/flush and baking soda to neutralize any remaining acids.

I plan to add coolant back in but not if there's still a bunch of gunk in there.

Good plan.

I'm thinking of going with the Toyota red coolant since I use that with my Camry, so if you have opinions on that I'd be glad to hear those too.

I also have a Camry and I love that Toyota red coolant. The 3.0L 6 has some kind of plate/cover on the rear side of the block. I had to remove mine to repair a fitting so I got a look inside the aluminum engine block. CLEAN AS DAY 1.

Always use distilled water (cheapest at WalMart) - never tap water.
And pull the plugs on each side of the block to fully drain the system.

Here is some related posts:
https://www.thirdgen.org/forums/cool...ml#post6198248
https://www.thirdgen.org/forums/cool...lant-type.html
https://www.thirdgen.org/forums/cool...-you-feel.html
https://www.thirdgen.org/forums/cool...eeze-3gen.html
https://www.thirdgen.org/forums/cool...ant-flush.html

And ASE doc has the best answer: https://www.thirdgen.org/forums/tech...ml#post6145463

The old green coolant, which should never be used in anything, had silica sand(ethylene glycol silicate) emulsified in the ethylene glycol coolant. Trouble is, the sand would fall out of suspension over time, especially in engines that weren't run for periods of time, leaving no protection. Nothing preventing the iron from rusting and the aluminum from corroding and metals from mixing in the fluid and eating at each other. Organic acid coolants, which is everything but the old green stuff, contains organic acids that prevent the metals from corroding. Unlike the silica sand, the acids don't fall out of the mix, so the corrosion protection lasts for years, even when a car sits over time.

The coolant to use in these early engines is Zerex G-05. It is an OAT(organic acid technology) coolant that also contains silica sand. The silica sand, aside from being the old tech choice for anti corrosion, is also a sealant to cover very small leaks and porosity. G-05 gives us the best of both the old and the new technology and it will protect your cooling system and engine for 5 years, even if you garage your car over winter like I do. Speaking of which, I'm due to replace my G-05 coolant this summer.

BTW, all of this information comes from the Prestone company.

 

citric acid is also another cheap way to flush. careful not to use too much.

 

Thanks guys! Really good info / suggestions here!! This helps a lot!

 

(FYI green coolant 30 years ago isn't the same green coolant today)

 

Theres so much info. I didn't realize how complicated coolant was! Thanks for putting it all in one place! makes it easier to do research / obtain info!

 

unreal, just unreal

 

update: Before I read the responses I had already put more flush in, but I also replaced the hoses which were coated with brown gunk which was slimy and kinda embedded on the hoses and hard to wipe off. .

The stuff that came out was actually pretty clear, just a bit murky but clear overall. I suspect the flush would take a layer of grime off the hoses and pollute the water heavily.



Just running hose water for now to do a cleanse, then will throw the t-stat back in and run distilled water to flush out, then will add 50 / 50 coolant / distilled!

 

For whatever reason the Zerex G-05 is not as abundant in stores as it once was. Luckily most newer cars use the OAT or HOAT coolant so you can just go to the coolant section and buy whatever coolant for whatever car you want provided it says OAT/HOAT and you stick with that manufacturer specific coolant. Although I've know for years that OAT/HOAT is superior I have yet to make the switch because my coolant passages all look good. I've changed the coolant out every 2-3 years so that may have been a factor. I've also read that inadequate grounding of the engine can cause electrolysis and expedite corrosion internally.

 

I stayed with conventional American green coolant because of the iron block and brass in the radiator. Might have chosen something different if I had an aluminum radiator. But I open up my cooling system probably every year and I like how fast the conventional green goes to work to protect after filling.

There's a good article starting in post #336,

https://www.thirdgen.org/forums/ltx-...ml#post5970973