Well, yeah it does because I started this thread to discuss on the generic
level water v glycol+water as a coolant for high temps, but on another
level it was to help me follow up to a discussion I had with my son, who
drives a Jeep and off-roads in desert heat, in which he said that he runs
water+surfactant in summer for increased cooling. (That he didn't flush
the system before winter arrived and the coolant turned into slush is a
sidebar -- or sideshow -- issue.)

I wanted to get back to him on the relative cooling abilities of
water/glycol+water and until the boiling point issue was raised I thought
I (and maybe some Vanagon owners, considering the number of them who
chimed in recommending water in summer) had it figured out. So I dunno
whether I have an answer for my son at this time, but that's not what this
list is about so I'll have let that go.

--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
Bend, OR
KG6RCR

On 12/13/2009 9:13 AM Keith Hughes wrote:

>
> 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)
>