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I was also going to chime in on this but Fred beat me to it with
my exact reply. But to add a little more, installing a cooler thermostat
does not necessarily mean the engine will run cooler. A normal factory
size radiator is designed to transfer just so much heat to the surrounding atmosphere.
To accomplish that, the water must remain in the radiator for a minimum amount
of time. A cooler stat will open fully at a lower temperature and cause
the coolant to flow at a faster rate. The factory stat will cycle the
amount of opening during normal operations and cause the coolant to speed up
and slow down. This allows the coolant to stay in the radiator long
enough to transfer more heat. The faster flow rate will send coolant back
to the engine before it has suffiecently transferred all the acquired heat to
the atmosphere. I’ve seen several people remove the stat completely
and then scratch their heads wondering why the engine still overheated. Basic rule of thumb, if you want a cooler running engine, you
need a cooler stat AND an oversize radiator. Both my Imperials have oversize cooling capacity with factory
size stats. They both run cool in all weather conditions. (and I never
turn off the AC) Both are set at factory timing specs. I run
premium fuel with lead additives in every other tank-full. Both engines
have right at 100k miles on them. No pinging and no abnormal behavior. Ken 67 Crown 4 Dr Ht 68 LeBaron 4 Dr Ht From:
mailing-list-owner@xxxxxxxxxxxxxxxx
[mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of Frederick
Joslin I have to put my 2.5 cents (with inflation) about thermostats. A thermostat is designed to get an engine above the thermostat setting
quickly and to keep it there. The radiator keeps the engine cool. This is not a
function of the thermostat. If you have excess cooling capacity in the
radiator, the engine should run close to the thermostat temperature. The
thermostat keeps the temp above its set point and the radiator has the capacity
to drop the temp below that point so it should cycle around the thermostat
temp. However, if the engine puts out more heat than the radiator
can transfer to the environment then the temperature will increase
until the heat produced is balanced by the heat shed. Note that as the radiator gets hotter relative to the environment (air temp)
the heat transfer becomes more effective since the rate of heat transfer is
proportional to the temperature difference. Conversely as the air temp gets
hotter (Arizona in the Summer) the effectiveness of the radiator decreases
because the temperature difference is less. Heat is generated in the engine and is transferred to the coolant which is
shed through the radiator. It is the temp in the engine that we care about and
there are two transfer locations; the heads/block and the radiator. Really
three locations since in the radiator the heat is transferred to the radiator
metal which is then transferred to the air. All of the transfer locations need
to work effectively for a good cooling system. If you have poor heat transfer
in the heads/block to the coolant you risk pre-detonation and potentially other
issues regardless of how well the other parts work. . Fred Joslin |
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