I have been watching this radiator dialogue and attempted to interject some
water chemistry considerations a couple of weeks ago, but was unsuccessful.
Here goes again.
Copper and aluminum are both excellent heat transfer materials. However they
don't mix well. In fact, they are bitter enemies! When they are put
together the result is rapid and destructive corrosion. Even when linked
only by water in an engine cooling system, the result is eventually the same.
Switching one component while leaving others unchanged can be bad news. An
example is installing an aluminum intake manifold on an engine with a copper
cooling system. I just pulled mine again this weekend in the course of
disassembling the engine. I last pulled it about 15 years ago. Both times
the water passages have been severely corroded- the result of dissimilar
metal activity. Perhaps you have noticed a white or light grey sludge in the
bottom of your radiator if you have some aluminum components - it is Alumina,
the product we manufacture here, which is Al2O3, aluminum oxide. The white
scale on the inside of the water passages is the same stuff. Alumina is an
excellent insulator (makes great refractory and things like the heat sheild
tiles on the scape shuttle), but doesn't transfer heat well at all. If you
are going to switch some components, you need to think about switching
everything - radiator and heater core (and thermostat). Otherwise you will
have constructed a battery and the aluminum component will be sacrificial
anode. Could be your intake, radiator, those expensive aluminum heads.
See you in Eureka!
|