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Was said: <Why does it develop a vacuum on cool down?>
Let's explore this. Let's convert this theory to facts.
Just use your favorite drink container. No, not a beer can.
1) You can use any container that has a small neck. Fill container with
water, place a balloon over the bottle neck.
2) Put a pan of water on the stove, turn to high heat, place your drink
container inside.
3) As it heats up, you will see the balloon expand. When it cools down, you
should see balloon suck into bottle.
Heated coolant has excited molecules that get further apart from each
other. As it cools, these molecules get closer together. It's a tremendous
force.
I did all sorts of little experiments like that with my plane. Like I
covered one exhaust pipe with rubber and watched how it behaved. I installed an
atmospheric pressure sensor inside exhaust and watched the pressure pulses.
There are a lot of physics principals that we don't have a good grip on
because they are difficult to measure. I work in science museum where we expose
people to these every day. It's a blast.
-al wick
Artificial intelligence in cockpit, Cozy IV powered by
stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland,
Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
On Wed, 8 Jun 2005 22:31:57 -0400 WALTER B KERR < jbker@juno.com> writes:
After you shut off your engine, the 7 psi gradually drops over the
next few minutes. It only takes around 12 minutes for the system to develop
a vacuum relative to atmosphere. At that point the little valve in the
radiator cap opens and allows fluid or air to flow into system. (Check out
your rad cap, can you find both valves?)
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Al, if your cap is a 24 psi cap which you said you could run with full
bottle. Why does it develop a vacum on cool down. I have never noticed this
on my system, but on the other hand probably never looked at it 12 minutes
after shutdown
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