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94' LHD Supra TT V160 Targa
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Discussion Starter · #1 ·
Hello!

I’m doing a coolant flush. Moving from yellow to red coolant.

Is it safe to run the car with only water for about 30 min to get the thermostat to open and then drain everything and do it again untill the water coming from the engine/radiator is clean?

Thanks
 

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Yeah, you can run straight water, just make sure to use distilled. That's the proper way to flush out your coolant system. If you want to run no anti-freeze, then I'd recommend a bottle of water wetter added to the water.
 

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For a temp thing to flush out old coolant, no problem at all!

But if you're running straight distilled water constantly, I'd strongly recommend adding 'water wetter' or another anti-corrosion additive. Once rust starts in your coolant pathways it's a right bastard to fully clean out.
 

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You can run water temporary.

IN the end, no amount of water wetter will stop the iron block from rusting. You have two dissimilar metals ( iron block, Aluminum head) in contact and the water is serving as the solution to create the necessary electrical difference to cause ion exchange to create iron oxide (and to a lesser degree, aluminum oxide).

Unless there is a very specific need... 50% anti-freeze works great and if you are in very hot climate, 30% anti-freeze. In both, the boiling point gets raised.
 

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Discussion Starter · #6 ·
Great, thank you everyone! Much appreciated! I'll only run water a few times to clean the last coolant out, before putting in the Toyota Red. Just want to make sure to get it all out, as i heard it is not a good idea to mix 2 different coolant types... I hope i will be able to get all that yellow coolant out :)
 

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as everyone said already you can use 100% distilled for quite a while
Many tracks will require 100% water, no anti-freeze is allowed on the race track.

as a side info
Pure waters, such as deionized/distilled, the more pure high resistance water is, the more it can scavenge for (metal) ions, leading to corrosion. For example in my lab we use incubators for cell research, 5% CO2 and 37*C environment surrounded by stainless steel with a water bath to maintain humidity. The protocol to refill the incubator is using ultra-pure water, but the manual states that a small amount of sodium bicarb needs to be added to prevent the pure water from attacking the stainless steel, leeching metal ions from it.

This is perhaps one reason we need to add at least some small % anti-freeze with that 100% distilled water, as an anti-corrosive / preventative measure. The water seems to need some form of ionic and solute components and will find them one way or the other.
Highly resistive water prevents electrolysis because electrons need ions to conduct through liquid but the water itself can pull those ions from nearby materials, even just from friction and natural wear in some flow systems, so the resistance will drop over time and water may need to be replaced more frequently in some than others.

Additionally I would be willing to bet that an (especially old) engine coolant system contains so many ions and solutes already, mineralized dissolute components abound, that even after a severe flush, it probably hardly matters if the water going in is ultra-pure or deionized as they will undoubedtly find ions waiting to dissolve into solution once they enter.
 

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Discussion Starter · #8 ·
as everyone said already you can use 100% distilled for quite a while
Many tracks will require 100% water, no anti-freeze is allowed on the race track.

as a side info
Pure waters, such as deionized/distilled, the more pure high resistance water is, the more it can scavenge for (metal) ions, leading to corrosion. For example in my lab we use incubators for cell research, 5% CO2 and 37*C environment surrounded by stainless steel with a water bath to maintain humidity. The protocol to refill the incubator is using ultra-pure water, but the manual states that a small amount of sodium bicarb needs to be added to prevent the pure water from attacking the stainless steel, leeching metal ions from it.

This is perhaps one reason we need to add at least some small % anti-freeze with that 100% distilled water, as an anti-corrosive / preventative measure. The water seems to need some form of ionic and solute components and will find them one way or the other.
Highly resistive water prevents electrolysis because electrons need ions to conduct through liquid but the water itself can pull those ions from nearby materials, even just from friction and natural wear in some flow systems, so the resistance will drop over time and water may need to be replaced more frequently in some than others.

Additionally I would be willing to bet that an (especially old) engine coolant system contains so many ions and solutes already, mineralized dissolute components abound, that even after a severe flush, it probably hardly matters if the water going in is ultra-pure or deionized as they will undoubedtly find ions waiting to dissolve into solution once they enter.
Wow, thanks! Great information! Thanks for sharing! :)
 

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For a temp thing to flush out old coolant, no problem at all!

But if you're running straight distilled water constantly, I'd strongly recommend adding 'water wetter' or another anti-corrosion additive. Once rust starts in your coolant pathways it's a right bastard to fully clean out.
I noticed some light rust in my water neck when replacing the radiator hose, other than pulling parts off and wire brushing them, how do you actually get the rust out? Is there a solvent that's safe to run through the entire coolant system?
 

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I noticed some light rust in my water neck when replacing the radiator hose, other than pulling parts off and wire brushing them, how do you actually get the rust out? Is there a solvent that's safe to run through the entire coolant system?
It's not a solvent you need but something that will react chemically to the rust and neutralize it. There's a few shadetree chemist methods involving vinegar+distilled water, or citric acid+ distilled water, or baking soda + distilled water, that have worked with success for some folks.

I've used a product in the past called Evaporust (now called Thermocure, apparently) and that involves draining all the coolant, pouring in the Evaporust, and topping it off with distilled water and just driving it like that for a few hours to a few days. Drain all that junk out, flush with distilled water, and do another round of Evaporust if needed or just top off with 30/70 or 50/50 as desired.
 
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I bought a bag of powder evaporust and I did the thing where you try to open the bag and it explodes everywhere, dust all over the place. Gota say, does not taste good. Haven't even tried it yet on anything other than the wood floor and clothing and skin. I give the taste a 2/10 though, spicy

I heard good things about it, wanted to try it. Just didn't expect to try try it.
 
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