A old friend claimed that he was told to use distilled water with his new heads? Does this sound right? I believe they were aluminum heads if this matters? What is the purpose behind using distilled water? Thannks in advance-

 

Using distilled water in your cooling system as opposed to whatever comes from your tap or the hose outside will help prevent corrosion in the cooling system. It won't stop it, but corrosion will take longer to form.

- Justin

 

The better brands of antifreeze also specify distilled water if you actually read the directions. It makes a pretty significant difference in how long it takes for corrosion to build up.

Aluminum is more prone to corrosion than iron anyway, so it makes good sense to use distilled water with aluminum parts.

 

distilled water also has a higher boiling point than regular water does, most antifreezes have anticorrosive additives anyways so i couldn't fully justify distilled water just for corrosive purposes. your suppose to flush your coolant system every year anyways and brakes every 2 but people dont and wonder why things corrode...

 

tap water is filled with minerals that will cause "scaling", a buildup of mineral deposits throughout cooling system i.e. block, heads, radiator..., it will form a coating in passages that will insulate the heat instead of aborbing it and taking it to the raiator to be cooled, causing overheating...
even a radiator or cooling system flush wont remove the scaling
basically if you really care about your engine and want it run at its peak use distilled water only cost you a couple bucks more than just using tap water

tim

 

Use distilled especially if you don't run coolant.

 

I don't think this is as important as no impurities, but distilled water also has no ions, so it won't conduct electricity. Might be nice to know if you ever blow and hose and soak your alternator nothing bad will happen .

 

Only if the water has less than 2ppm inorganic impurities will it not conduct electricity. I wonder how many "distilled" waters out there have that little amount.