Jerry Hey wrote:

 Slightly off topic, but I just bought a l988 normally aspirated RX-7
 which has a newly rebuilt engine and a clean radiator. It is
 exhibiting cooling behavior which I don't understand, in that the
 water temps are fine at freeway speeds but go up to near the redline
 in stop and go traffic.  Fan seems to working properly--no bugs on
 the rad.      Jerry

That is strange Jerry. Check the thermostat. Somebody may have put
in the wrong
kind. Mazda thermostat are unique. They close off a bypass passage when they
open. If the wrong kind is used they will not close the bypass passage and
at low RPM water pump speeds much water will be merely bypassed and not
routed through the radiator.

Paul Lamar

Jerry Hey wrote:

I'd  like to thank everybody who offered their analytical skills to
solve the problem.  I did check the coolant levels looking for
trapped air, and also checked the viscous clutch although I don't
know how this is supposed to operate.  Mine spins faster with
increased engine rpm just as if it was a solid connection.  That is
how it looks.  With the engine off, it freewheels with a little drag.
Anyway the prize goes to Paul.  The problem disappeared with the
installation of a genuine Mazda thermostat.  I could not see any
physical difference between the thermostat from Mazda and the one I
took out, except that the latter was stamped NTC.   The thermostat I
installed came out of  my aircraft engine.  You can be sure I will
replace it with a genuine Mazda part or none at all.        Jerry

YES! :-)

Paul Lamar
 
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