Ed,
Ed Anderson wrote:

One thing to consider anytime you place a filter or screen in any fluid flow
line where you might expect contamination (otherwise why put the filter) is
that should the filter become clogged - then all fluid flow ceases.  Not to
say a filter/screen should not be used, however, its my opinion that the
source of the clogging elements should be determined forthwith otherwise the
condition will simply return.
  

First you have to determine if clogging elements exist.  Then you can track them down.  I would hazard a guess that everyone has them, but not large enough and in large enough concentrations to clog a radiator.  I recall a recent thread on the alarming amount of scale and trash someone found on a factory new engine - evidently on account of Mazda test runs them and doesn't clean them out well enough.  Even if a fellow cleans out a lot of trash, how can we know how much he missed in all the nooks and crannys of the block?

I have not had any problems with clogging or scale etc.  I use Preston
Antifreeze and Distilled water when I fill the coolant system.
I am fairly certain that neither has Tracy with over 1600 hours - so it
clearly does not happen as a matter of course.  Some tap water (Particularly
in the western part of the country) has a high gypsum? and other scale
producing mineral content.
  

I would postulate that Tracy hasn't had anything like a damaging blockage, but how well do we know that he isn't working on one but much more slowly than the originator of this thread?

I took out the thermostat to preclude interference with coolant flow and
perhaps that may contribute to more constant flow and perhaps less
opportunity for scale to build up?  Just a thought.
  

Perhaps we could fashion a quickly removable filter and patch it into various systems for a while just to check what it picks up.
Like, I wouldn't have thought it possible to block up a whole damned radiator ... Jim S.

Ed A