Hi Rick,
To measure inlet and outlet water temperatures accurately, you need at least
a thermocouple in the top inlet hose and one in the bottom outlet hose and an
instrument to read them. These can be slipped between the hose and the
radiator or engine inlets and outlets, making sure that the metal bare ends
of the thermocouple are in the coolant and not shorting out on the metal. The
thermostat must be blocked open. the temperature drop should stabilize
between 8 to 10 degrees in constant speed driving above 50 MPH. A perfect
system will show about 10 degrees differential. If you make measurements at
various constant speeds in your normal driving range you can get an idea on
the speed sensitivity of your car's cooling. You can run an idle test for up
to a half an hour and get an idea how your fan and air recirculation problems
are. If you are running on the track than you need someone or a recorder to
monitor the transient water temperatures throughout the run.
Using inlet and outlet temperatures at various operating conditions is the
best way to analyze the total cooling system. For instance, if you are having
cooling problems at highway speeds and the temperature drop is more than 12
degrees then your problem is probably due to low water flow. If the
temperature drop is less than 8 degrees than the problem probably has
something to do with the air side of the system, such is low air flow, poor
fins etc. I'm sure I will be corrected by you rocket engineers on what I've
said here but at least some ideas will result.
John Logan
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