What variations do you see?
Peter
My engine is a 1986 13B. At first, I did not
have a coolant pressure gauge. 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. I have always used a thermostat and a ~one litre coolant
reservoir connected to the pressure cap. When cold it is ~one quarter full.
When hot, it is 9/10ths full. Also I have a canopy defroster which takes hot
coolant from the heater outlet in the rear housing and returns the coolant
to the pump near the thermostat.
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.
So, I was hoping that the oil temperature
would come down also to about 170-180F. My Mazda oil cooler in
installed upside down and I wonder if that could impede its cooling
function.
MERRY CHRISMAS TO
ALL!
Yvon Cournoyer.
Rotary Powered Zenair Zenith.
(CH-200)
Thanks for the details Yvon. I believe there must be a
thermostat in the oil cooler. I have seen similar fluctuations in oil temp.
Peter