Modern Vespa

EDM uses deionized water (which is actually more corrosive than distilled) because it doesn't carry current. If normal tap water was used in EDM it would not spark to the right place.

Also, notice that everything inside the EDM tank is stainless steel or plastic (or copper wires)? Low alloy steel would rust right quick in the bath.

Nope.

Deionized water has no minerals in it. Or shall I say, decent quality DI water has less than 5PPM dissolved solids.

Typical process for making DI water:
1. Mechanical filter. Removes solid materials and preps for RO membrane.
2. Softener. Replaces most dissolved solids with sodium and chloride ions which are easier to flush from the RO membrane.
3. Reverse osmosis membrane.
4. Deionizing bed.

If you do all that, all you have is water. No minerals, no bacteria, no dissolved organic material.

If you're just buying a bottle of distilled or DI water from your local garage, I would think that the difference between them would depend more on how well the process has been carried out and how well the plant is maintained, than on the fundamental difference between distillation and deionisation. Both processes, done properly, are capable of producing extremely pure water.

I would be interested to know why either one would be more corrosive in an engine than the other. Is this corrosive property neutralised by the coolant? In which case, if it exists, does it matter?

I interpreted Poocher's original post as how to complete a coolant flush. Why are we discussing coolant? I could be wrong?

I know. By page two there should be no connection at all to the original post.

Please try to avoid the "C" word guys.

Hi Madison,

And I think that's the problem Madison..."if you do all that". Many companies producing DI only make a basic product. If it were done to best practice it would be as pure or purer than DW. We are in fact both right. In the trade, at least here in 'Urop', we normally only recommend the use of Distilled water for coolant mixing. The reason for that is much of the DI water you buy is less pure than Distilled. We know that because my company tested several brands of DI and it just didn't stack up to DW. It's also know in the trade that this is the case. In fact, the levels of bacteria were incredibly high in much of the DI. It costs money to purify water to good DI standards and many companies who provide run of the mill DI use a basic process and this produces only basic 'purified' water which still contains impurities.

There is plenty of stuff about this on the tinternet highlighting this issue. But at the end of the day even less pure DI is better than tap water. NEVER use tap water, it's just not acceptable and can damage your motor longer term.

But unless you are using a flush additive, just rinsing the system out does nothing to remove build up.