Distilled or De-ionized for cooling system ?

[DieselMonkey]

To cut the story short, I work for a company that uses a large amount of De-ionized water for their manufacturing operation, so I have a free supply.

I was warned that de-ionized water alone, eats bare metal alive ! And on our EDM wire errosion machine, that is correct, a lump of mild steel left in over night will be thick with rust the next morning.

But still, I was under the impression that the main cause of cavitation and corrosion within a cooling system was the water quality. As you know, de-ionized water is free from dissolved solids and so, you would pressume it would be the best solution if living in a hard water area.

I contacted a materials engineer at Detroit Diesel, and he highly recommended using de-ionized water if at all possible. If not, distilled. So basically, i'm now running De-ionized water mixed 50/50 with a diesel coolant in all my vehicles. Thats 6 diesels in all.

Has anyone had any experiences using De-ionzed water in a cooling system ? The process used to de-ionize the water involves adding acids to it, if i am correct.

I live in an area where Cummins, International & Ford New Holland diesels have problems with cavitation corrosion, due to the water quality. That is why I am now using de-ionized. In over 1 years use in a Ford New Holland diesel, no problems so far with any materials in the cooling system (that I know of), no internal or external leakage of coolant.

Any experiences, good / bad, would be much appreciated.

Matt

Cavitation is not caused by using the wrong type of water. HERE is a good article on what cavitation is.
I use distilled water in gallon jugs. Tap water is a BIG no-no. The only time I'll use tap water is when flushing the system with a garden hose.

De-ionized is best for batteries. I've seen what it can do to metal on it's own and I don't know if the coolant chemicles will prevent that over the long haul.

[DieselMonkey]

Yes I am aware of the correct meaning of Cavitation, but if you read the information in the link, you will see that water quality does come into it. Where I live there is a diesel repair yard littered with pitted out blocks, because of the water quality. Hard water can cause hot spots and scale, which will allow the implosion of the air bubbles a better chance of drilling through the material.

SCA's went a long way here to solving the problem, but I think the de-ionized water will knock the problem on the head for good, but you never know. The detroit diesel materials engineer was very clear on his point that de-ionized water is preffered, and distilled where de-ionized wasnt available.

I think i'll carry out a little test using a sample of striaght de-ionized water and the coolant solution and 2 peices of identical grade steel. Maybe try it with aluminium also.

Regards, DM

[ConnClark]

Distilled water is probably best. Since it is known not to cause problems.

[babymog]

Cavitation pitting is a big problem in wet-sleeve engines like the DD engines, not sure it is really an issue in a dry-sleeve engine like M-B car engines, ... correct me if I'm wrong.

I use distilled. What you want in water is something that doesn't conduct (pure water doesn't conduct electricity), that reduces dielectric corrosion problems where you have metals with different electrical potentials (eg: aluminum and iron) sharing the same water, proper pH should be handled by the additive package in the "anti-freeze", and proper wetting should be accomplished by the anti-freeze also. A fluid devoid of minerals or dissolved solids helps to prevent the buildup of sedimentary deposits as does proper pH, distilled water shouldn't have any dissolved minerals/solids.

- Jeff Miller
190DT

[PaulH]

Have used distilled water for 15 years in my 603 motor. ( The dealer changed the antifreeze before.) No problems.

[SD Blue]

An excellent carbon block filter will sufficiently remove any problems with your water. And it will significantly improve your drinking water quality as well for an added bonus.

[Pete Burton]

By the time your deionized water is heated in your engine block for the first time, it's been completely reionized by whatever metal ions it can get (and it will get them). My gut feeling is after the water has its ions to reach an electrochemical equilibrium the water will be as good as regular distilled water.

[ConnClark]

I think I like Pete Burton's last assesment of the problem the best. I would still go with distilled water though.

[bioTD]

The main difference between de-ionized and distilled is the way it is produced. One by evaporating and recondensing, the other by chemical purification process. The actual chemistry depends on the method and equipment used. For the purpose of mixing with coolant, either is fine. If you have free supply of de-ionized use it. There are actually ASTM specs for water to mix in regents, I think ASTM D1193 Specification for Reagent Grade Water.

For the purpose of putting into your engine, deionized or distilled is agressive against metal (especially cast iron block), but if run in a circle in your cooling system it would come to equilibrium and will definitely be fine once mixed with coolant. Tap water has dissolved solids and things that precipiate and build up in you block and radiator, that's why recommend to not use tap water.

I also work at a place with free DI water and have been using it for years. You can even use unmixed to 'flush' the crud out of your cooling system, since it will try to pick up the deposits that are already in there.

[DieselMonkey]

Thanks guys. Well, I work for a pharmaceutical company who uses DI water for their manufacturing operation. The site engineer who goes and collects it for me said to beware, they spray the DI water on an Aluminium heat exchanger core (dont know why), he says the alu. cores simply crumble and fall apart after a year, so thats why I contacted Detroit Diesel who strongly recommended it. I've been using it in a lot of machines, inc my Mercedes 190 and VW Golfs. There havent been any problems yet.

Maybe someone will have some more comments about its effects on the aluminium cores, but if not, thanks for the input.

Matt

[pawoSD]

Do you really need enough of it to have to get it free?

I just get a 5 gallon jug of distilled water at the local store for about $2, plenty for both cars, and then a couple gallons to drink while I am working.

[DieselMonkey]

The Ford NH engine, 6.6L holds 21 litres of coolant, the IH D358 engine (great engine by the way), 5.9L, holds 17 litres of coolant, Golfs about 7 litres and Mercedes 190 around 10 litres I think. So half all of that, and it doesnt be long before its gone. I wouldnt know where to get Distilled water. At a local store they charge the equivilant of $2.50US for distilled water for car batterys, about 1.5 litres. It would be a bit expensive to get 25 litres +.

I suppose the De-ionized water must be ok. I've tested it with a Mac tools coolant tester, not an expensive tester, just a litmus paper type test, which showed its pH to be right on the money. I use a little SCA also.

Regards, Matt

[DieselMonkey]

Hey, funny you should mention drinking the distilled water...

When I started asking the guy in work if he could get me De-ionized water, they where all asking me why I wanted it in the canteen. So the discussion started about de-ionized water because we had just bought a new Charmilles Robfil EDM machine which de-ionizes its own water, so it was a current topic of discussion. We hadnt come across the effects of this water before, and we wernt aware of the dangers of it also.

So the guy gets me the stuff, he tells me its sitting waiting by my car for leaving time. One of other guys just asks him out of the blue...what effect drinking it would have, since we had just seen how damaging it can be on mild steel on the EDM machine. He said, in a very small amount, it would be good for you, but more than 1 glass could be seriously dangerous. Apparently, de-ionized water tries to 'leech' ions and properties from where ever it can. I think someone mentioned that above, in an earlier post.

Wonder what it could do to the body ???

Its an interesting subject. Looks like harmless plain water, but has so many different properties and effects.

Regards, matt

[Pete Burton]

I won't get into why testing the pH of DI water with litmus paper doesn't mean much. Just use the DI water, it'll reionize itself faster than a dog runs to a gutwagon.