Deionized water vs. Distilled water for coolant flush

Greetings,

 Never done a flush before. The bottle of Toyota coolant says use deionized water. Is that the same as distilled water? If nit where to I get this magical elixir?

 As an aside I <em>think</em> I see where the thermostat is. I suspect It is stuck on my Xrs. Do I flush first, then change it out? Do I remove it, flush, then change? What is the smartest way to handle the flush and T-stat change?

Thanks Jason

Deionized? That's really strange. It's not the same thing as distilled water (although can act as a substitute for it - deionized water is also distilled) but AFAIK deionized water is only needed for those awful old batteries that need to be topped up. Around me the gas stations sell it.

I can't imagine why they require deionized water in a coolant system though...

I used distilled water when I did the cooling system in my M3. It was the first time I've ever done that, in all my previous cars I have used tap water.

In short, I'm sure distilled water is fine.

Functionally equivalent.

Thanks. Not sure the rest of my post showed up properly, so here it goes...

I think my Xrs has a stuck T-stat. Do I flush it then change it, remove it then flush it, or is there a smarter way to change the T-stat and replace the coolant?

Thanks

No there not the same as some imply. De-ionized water will actively seek minerals to absorb. It can and will open any tiny leaks in the system. DI water will eat through most metal pipes quickly and some plastics too. DI can be but most of the time is not made from distiled water but 6ft tall resin filled filters connected end to end the system we have here at work uses 4 filters.

DI water is offten used as final wash after cleaning steps to remove any last bits of chemical residue.

If you have an ohmmeter it is pretty easy to check how ionized your "water" is. All the grocery store distilled bottles I've checked have been quite non-conductive. Certainly more than good enough for engine coolant use.

Deionized water can contain uncharged non-water molecules, while distilled water should just be H2O (and some HO- and H3O+). In other words, distilled water is a superior subset of deionized water--not the other way around.

Dr. Hess wrote: Functionally equivalent.

Not if you're drinking it.

GameboyRMH wrote: I can't imagine why they require deionized water in a coolant system though...

It won't be deionized for very long - as soon as it starts hitting metal.

Knurled wrote:

GameboyRMH wrote: I can't imagine why they require deionized water in a coolant system though...

It won't be deionized for very long - as soon as it starts hitting metal.

my point exactly. It will pull molicules from what ever is esayest like build up around a pin hole...

Your cooling system won't be able to tell the difference.

Twin_Cam wrote: Your cooling system won't be able to tell the difference.

Your wallet sure will though.

So I got 4 gallons on distilled water from the grocery store. Do I need the flush and fill kit? I don't like the idea of adding two leak points by cutting the top hose to add a T. How is it done without that?

I was taught that you used distilled in batteries to help with the transfer of electrons from the plates, whereas you want to use plain tap water in cooling system to inhibit the water from pulling material off the block, radiator etc. Why would this be wrong and am I confusing de-ionized water with distilled in this case?

I've always used tap water in my cooling systems. The dealership I worked for had distilled (de-ionized?) for batteries.

Now I'm confused!

I always buy premix coolant, in theory it probably has better water than we have locally.

In reply to Knurled:

The coolant i have is pre-mixed. I just didn't want to use that for the flush.

I would personally not cut a good hose to add some sort of T just for the once every couple years I flush the coolant system. I usually just drain and refill.

Tap water is fine for flushing the system. Just drain it afterwards. I've killed a couple of water pumps recently by keeping tap water in there for a few months. My tap water is horrible.

Tap water for the flush. Then pull a radiator hose and put a shop vac on it and suck all the water out. Then refill with distilled/deionized/reverse osmosis purified/whatever you want and Toyota Red Coolant.

I would replace the thermostat, then flush it, if that's what you want to do. Actually, I would just replace the thermostat, suck the old coolant out, and fill with distilled/reverse osmosis water and Toyota Red.

My mechanic had a simple answer. Change the thermostat, save the old coolant, use the new coolant, and top off with the old stuff.

I was always told that any potable water is OK to use in batteries and cooling systems. I have been doing that for many many years with no failures.