Given aweb.com, Jess
Guessing wrote:

What caused it to crack? Excess pressure, flexing or just old age?

The radiator is the OEM radiator on a 1990's vintage Toyota.

If they didn't make the top plastic, it would still be working, but two
decades is a decent amount of time for a $200 radiator.

Unfortunately, the whack-a-mole game failed in that it still lost pressure
this morning when I tested the epoxy temporary repair (until the parts
arrive).
http://img4.imagetitan.com/img.php?i...uretestkit.jpg

The question is how far can you drive on an unpressurized system?