A very late reply, but: 160 F is only ~72 C. The shutdown temperature is documented as being 85 C and well below actual hardware fail/damage, thus 185 F. So this is all within specification and it is correct that the Pi doesn't shut down. Seems something different. It is very difficult to reach 85 ...

the outer plastic of the larger black chip gets to 140º. That means the inside could be much much hotter. I suspect some part inside the chip that somehow regulates the heat has melted and now the pi just uncontrollably gets hotter after it is turned on. I am trying again now after it's being off fo...

My raspberry pi is overheating extremely fast after startup. I notice that yesterday when I was trying to figure out the GPIO pin stuff, I looked and the pi was extremely hot and had shut down. Within half a minute of booting, the pi overheats to 140ºF and shuts down. Any ideas?