Just one note: With the thermostat closed, it does not slow the
fluid moving through the block. If anything, it speeds it up. The
coolant in the radiator does need time to disapate or transfer the heat
in to the air. This does take time. If you take a hot cup of tea move
it in and out of your refrigerator, it won't cool as fast as it would if
you just left it there, (completely over simplified here). These cars
are not Nuclear powered, and they are not going to melt down even if
they overheat a bit. My old Alpine Did melt a piston when it finally
died. It was cold out that night, and my cooling system was working
just fine.
Bottom line: Keep it moving through the engine picking up heat
and helping to regulate the internal block temprature, and when it
begins to get too hot, exchange some of it with teh cold liquid out in
the heat exchanger (radiator), then close that valve again to help keep
the cold side cold.
Rich
> ----------
> From: W. R. Gibbons[SMTP:gibbons(at)northpole.med.uvm.edu]
> Sent: Friday, June 13, 1997 8:26 AM
> To: Michael Fisher
> Cc: alpines(at)autox.team.net
> Subject: Re: Radiator cleaner
>
> On Fri, 13 Jun 1997, Michael Fisher wrote:
>
> > Sorry Ray but I think you are missing some physics of the problem.
> I do fluid
> > dynamics for a living and have studied this problem in great detail
> (along with
> > several engineer and physicist friends around the country). I did
> not believe
> > this myself until I looked at the problem and tried it on several
> different
> > cars.
>
> I said that the thermostat might prevent the water pump from
> cavitating
> (so flow would be faster with an open thermostat than with no
> thermostat),
> and might direct flow so as to prevent hot spots, again providing
> better
> cooling with the thermostat in place. What I find hard to believe is
> that
> the thermostat improves cooling (at any ambient temperature) *because
> it
> slows coolant flow*. The argument that the thermostat slows flow,
> thereby
> keeping coolant in the radiator longer so it has more time to lose
> heat
> makes no sense to me. Slowing flow results in a temperature gradient
> in
> the radiator, which means the cool side of the radiator is not
> transferring as much heat as the hot side, and it also means that the
> engine passes more heat to each aliquot of coolant in the block.
>
> If I understand you correctly, you say that you and several physicist
> friends studied this extensively and you did not believe it yourself
> until you tried it and it worked. Did all your studies lead you to
> believe it was not true? I've thought about it a lot, too, and I
> conclude that faster coolant flow is always better. If removing the
> thermostat makes the engine run hotter, then either the thermostat
> helps
> direct flow to give an even temperature (certainly possible) or the
> flow
> actually slowed down when the thermostat was removed.
>
> If, on the other hand, your analysis led you to a sound theoretical
> reason
> why slowing flow would improve cooling, then I'd appreciate your
> explaining the physics in an understandable way.
>
> W. R. Gibbons Dept. of Molecular Physiology & Biophysics
> Univ. of Vermont College of Medicine, Burlington, VT
> gibbons(at)northpole.med.uvm.edu (802) 656-8629
>
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