Date:         Sun, 13 Dec 2009 10:13:15 -0700
Reply-To:     Keith Hughes <keithahughes@Q.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Keith Hughes <keithahughes@Q.COM>
Subject:      Re: About coolant
Comments: To: Rocket J Squirrel <camping.elliott@gmail.com>
In-Reply-To:  <4B250D01.5030107@gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed

Rocket J Squirrel wrote:
> Well, that certainly complicates things.
>

Not terribly.  The same glycol concentration that depresses the freezing
point to protect you in winter raises the boiling point to protect you
in summer as well.  As long as your cooling system is adequate (e.g. not
a stock vanagon in the desert) the pressure maintained in the cooling
system will be high enough to keep the water from boiling.  But if the
cooling system is marginal, you'll reach the maximum system pressure
(start dumping in the overflow) and further temp rise will cause
boiling.  A 50/50 mix (volume/volume) of glycol will raise the boiling
point significantly (about 15°F or so - at standard atmospheric
pressure).  Unlike the freezing point depression, which maxes out at
about 70% wt/vol of glycol/water then decreases, the boiling point
continues to rise with concentration.   Basically, if you're boiling a
50/50 mixture, you got mechanical problems.

Keith Hughes
'86 Westy Tiico (Marvin)