even though it may not apply to this situation per say, but when the buzzer and light flash when going over bumps or just randomly the sensor on the top of the rad usually gets nasty and become loose. i had a mix of all these problems when i put my engine back in,,, it was fun to find and fix

 

My coolant light comes on every few weeks. At first I looked all over for leaks but couldnt find any. It looked fine on pressure tests. Eventually I took it to a rotary shop and they told me that the coolant o-rings were bad and I was forcing combustion gas into the coolant system and the car was slowly overflowing all of the coolant out of the reserve bottle. I guess I know what Im doing this summer.

 

damn, that sucks. well im still looking for leaks. wish me luck