Rep Power: 0

Ok so I have a 2003 Civic EX to start out with. She started to over heat on day so i checked the water lvl and saw it needed more. So i decided i would just flush the system and then refill it back to proper lvls, since i know i have about 85k miles on this fluid already. I also changed the thermostat on it during the process. (I replaced the thermostat with a failsafe brand from auto zone)(i used a 60%-40% ratio for the radiator fluid).
Well anyways the car no longer overheats and runs fine but i have a bad coolant leak coming from the battery side. The coolant splashes are as high up as the battery box. in addition the reservoir keeps filling up and the radiator keeps draining. I have run the car for 10 mins on idle, after driving home from work, looking for leaks but couldn't find one so i am guessing the leak only occurs at higher rpms.


Any help anyone can offer would be appreciated greatly.

 
Rep Power: 518

Blown head gasket.

Search here in the forums to your hearts content.

 
Rep Power: 186

As ezone pointed out, head gasket. Those symptoms above are a dead give away.