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My coolant temp sender was located in the coolant
pump body close to the thermostat. Once I had the air out of the system, it
would maintain pressure for long periods, several days and more. When I needed
to remove the pressure cap on top of the pump, coolant would burst out under
pressure, so there must have been some air left in there. Oil and coolant temps
had to be monitored at WOT climb but would stay close to 200F at cruise.
Later, I moved the temp sensor to the rear housing
where Mazda had its temp sensor. Then I installed a coolant pressure
guage and put the pressure sensor in the front housing on the sparkplugs
side. There is a convenient threaded hole there for a pressure sensor.
Then, I connected the hot coolant outlet on top of the rear housing to the
top of the coolant pump body. So now, at ambient temperature, engine cold.,
there is no pressure in the cooling system. I can remove the pressure cap and
loose only a few drops of coolant, negligible volume. When I start the engine,
the gauge shows no pressure for long minutes, 10 sometimes 15 minutes.
Coolant pressure appears to be proportional to engine rpm, but I am still
checking on that. The max coolant pressure I have seen is about 10-12 psi at
5500 rpm. in cruise. Temperatures are lower, both at WOT climb and cruise.
Oil ~190F (I wonder if there is a temperature regulating mechanism inside
Mazda's oil cooler) and coolant ~180F. But that may be due to colder
weather. Cloudy and cold around here, at this time of year.
(Sherbrooke, Québec.) The overflow bottle (coolant reservoir) performs as it did
before, so no worry there.
So, coolant temperature has come down and
that is more important to me than coolant pressure. We will see next summer
if my cooling system is really more efficient.
Yvon;
One reason your cooant temp is lower is
likely because of the change in the postion of the sensor. At the
rear housing the coolant is only half way through the
engine. Although most of the heating is on the plugs side, the
temp back at the pump housing would be expected to be a little
higher.
Al
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