Overheated on track - now what?

[Pete_89T2]

Originally Posted by infernosg

Bottom line: is there any way this could be attributed to a bad thermostat or leaking radiator/water hoses? If not, like mentioned above, it looks like rebuild time.

Not the thermostat, since it's an internal part. But in theory, if water can leak out of an extrenal part exposed to air such as a hose or radiator, then air can get in too. But you tested the system with the pressure tester and it passed, most likely you would have found a leak. Only exception to that I can think of is since the pressure test is done under static conditions (engine not running, at whatever temperature it was at when you tested it), the test could miss a leak that only occurs under some combinations of dynamic conditions (i.e. temperature cycling, vibration, etc.).