[Mgs] Flushing the cooling system?

[Councill, David]

Actually Denise is correct although her explanation was a bit
simplified. Water will dissolve metals. In fact, distilled water is
mildly acidic. The dissolved minerals, particularly carbonates, add
buffering and increase the pH, but also can lead to deposits. Although I
usually use distilled or deionized water with antifreeze, tap water
often is fine depending on the area water quality and so long as the
coolant is changed periodically so it doesn't become concentrated. The
key is still running antifreeze with its anti-corrosion chemicals or if
in a warmer climate where freezing is not a problem, there are other
additives that provide the protection needed.

I should also mention that water can become acidic through dissolved
gases like carbon dioxide or through exhaust gas. Thus a head gasket
leak with only water as the coolant can introduce corrosion problems. 

David Councill
Former chemist (water, coal, soil)
67 BGT
72 B
Soon to be - 73B



-----Original Message-----
From: mgs-bounces at autox.team.net [mailto:mgs-bounces at autox.team.net] On
Behalf Of Simon Matthews
Sent: Monday, March 09, 2009 9:20 PM
To: Denise Thorpe
Cc: mgs at autox.team.net
Subject: Re: [Mgs] Flushing the cooling system?

Denise,

I think that your suggestion that the water cannot dissolve the metals
(or rather the corrosion products)  because it has dissolved minerals
in it is false.

Anyway, both argue for changing the water a little as possible in
climates where anti-freeze is not required.

Simon