George P. Richardson wrote:
> EPaul21988@aol.com wrote:
> > In a message dated 97-02-25 00:46:01 EST, johnhaynes@som-uky.campus.mci.net
> > (John Haynes) writes:
> > I'm now lost on this one. You agree that one reason for overheating is the
> > absence of a thermostat, but you disagree with the theory that the
>thermostat
> > functions as a physical barrier to slow coolant down and allow more heat
> > transfer ? Why does the absence of a thermostat result in overheating then
> Actually, the real reason is the *pressure* difference. The thermostat
> causes a change in pressure. The water in the radiator, before the
> thermostat, is under pressure from the water pump, forcing it to give up
> heat. The water after the thermostat, in the engine block has a lower
> pressure, allowing it to absorb heat. Substitute the appropriate parts
> of an automobile air confitioner for the water pump, radiator and engine
> block and you'll get the idea.
Oh no! Yet another theory! It seems to me that the one thing
that can be agreed on here is that everybody here has a
different "understanding" of how a cooling system works!
:-) :-)
Anyway, my opinion (possibly mistaken) is that the cooling
has very little (if anything) to do with pressure. Nearly
all of the pressure in the cooling system doesn't even come
from the water pump, but from some of the coolant boiling
and producing steam which increases the pressure throughout
the cooling system. For the most part (not entirely) the
pressure is constant throughout the cooling system, since
it is a closed system.
But, if the cooling has little to do with pressure, then
why is there a pressure cap on the radiator, one may ask?
The fact that the system is pressurized *IS* important, but
that is because the pressurized system increases the boiling
point of the coolant. For some reason (unbeknownst to me)
it is necessary to keep the coolant liquid for the cooling
system to function well. (I speculate that liquid coolant
is a much better conductor of heat than steam [boiled coolant]).
Anyway, I'll go home and read "The Way Things Work" again
tonight, and see if it helps muddy the issue at all. (By
the way, this is in *excellent* book to help understand
basic mechanical, electrical, and cooling systems -- should
be a "must read" for home mechanics, and/or woolly mammoth
fans!)
--ken
'74 TR6 -- one that doesn't overheat, even if we're not
entirely sure how it stays that way... :-)
--
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
|