>Dan, just 1 question on your point #4- for flow separation to ocurr,
>wouldn't there have to be air trapped in the water jacket? How would
>that happen?
Same way propellers cavitate. When you cavitate a propeller, you create
a vacuum behind the blade by displacing the water so fast. The collamse
of that high vacuum pocket creates the noise that submarines so dread.
Also, the vacuum pocket sucks out some entrapped air from the water. So
it doesn't collapse completely, but instead leaves an air bubble to rise
to the surface.
The same thing can happen in your engine, but instead of having a
propeller moving through the water, you've got the water moving through
convoluted passages.
For obvious reasons, if you've got an area without water making good
contact to the surface, you lose heat transfer and get a hot spot in the
engine, though you will not see it on the gauge. The coolant is running
around the hot spot, not picking up the heat. In extreme cases, you can
overheat the heck out of the engine this way, while having a cold reading
gauge.
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