i have an 00 si, my car will overheat after a couple of days after filling with water/coolant. ive sat and waited for it to over heat and when it would i could not find any hose that was leaking nor was there water on the ground yet i loose coolant everytime. any ideas of where my water is goin? and no water leaking from the heater core. also when it gets warm and i shut off my car to go in somewhere and come back out to start it it will take forever for it to start, just keeps cranking and finally starts. any ideas would help

 

bump for some good answers!

 

Pressure test the cooling system and compression test the cylinders.

 

Is your radiator fan coming on?