>> There seems to be a common (mis)perception that water moving "too
>> fast" through the radiator will not lose enough heat and will cause
>> overheating.
>
>While I have not conducted a scientific study on the matter, I can tell
>you that I once bought a car with an A-series engine that always ran hot
>and discovered that there was no thermostat in the system. After a
>mid-range thermostat was installed, the engine temp immediately went
>down to normal and stayed there. I won't debate why, but that's what it
>did.
Removing a thermostat, as I mentioned in some examples, can have an
anti-intuitive effect by encouraging the formation of hot spots, and changing
the flow pattern. Normally, the therm. restriction encourages flow withing
the engine, normalizing the temps there. With no thermostat, the flow to the
back cylinders may be reduced, and cause localized boiling even though the
radiator temp is low. The steam would increase pressure (fast) and cause the
cap to pop, even though the temp of the radiator isn't excessive (unless the
steam forces it's way to the passages to the radiator, which is possible -
and the water in the radiator is still hot anyways). Note that the temp
guage bulb on the 1275 crossflows is in the head, not in the header tank like
the downflow 948/1098's.
Most of the debunking in that article had to do with the issue of
speed of water through the radiator versus temperature, not the side-effects
in the engine of attempts to increase the flow to the radiator. As I said,
taking out the thermostat is a _bad_ idea unless you really know the
engine in question (and are probably running on a racetrack at constant
high temps - and even then you may want to use a gutted thermostat or sleeve
to adjust the amount of change).
--
Randell Jesup, Scala US R&D, Ex-Commodore-Amiga Engineer class of '94
Randell.Jesup@scala.com
Exon food: <offensive words no longer censored - thank you ACLU, EFF, etc>
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