At 09:59 AM 4/21/2002 -0700, you wrote:
>I agree that running in the 200 degree plus range won't hurt an engine, if
>the gaskets and seals have been replaced with modern materials in the last
>10 years or so.
DB, there is some possibility that the "overheating" 440 was partially
rebuilt in the past 20 years, and modern seals were used. However, it has
survived the worst.
>The danger comes from localized boiling, which can cause vapor pockets in
>the heads, ... Uneven heating is what causes warping of heads etc., not
>simply
>high temperatures.
Actually, excessive temperature can hurt the engine on its own virtue. The
heads are hotter than the block, and the differential expansion can damage
the head gasket, even if no warping takes place. That's why aluminum heads
are more venerable. In my case, the 16 psi cap, the small amount of
antifreeze, and the rust mad apparently prevented the local boiling that
you mentioned. Another problem with excessive temperature is that the oil
looses viscosity, and the wear rate of the rings can increase. I am always
using Mobil 1 15w50 that has very high viscosity index (meaning maintains
viscosity at increasing temperature) which is perfect for this
situation. I even ran the engine at WOT at that condition reaching
240F. The car refused to go over 125mph, probably because the super hot
radiator heated the under-hood air causing loss of air density and thus
performance. No engine damage though... In retrospect, I shouldn't have
pushed it, but apparently these old 440's are tough.
D^2
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