kamaolakid

Now things are a bit more complicated. I was sold on the water pump idea until I saw some flow through the radiator. My original post was after I had the car running for a while with the radiator cap off and no coolant leaking. A few hours ago I tried the exact same thing except this time coolant began gushing out. This means that not only does the water pump work, but so does the thermostat. The fans also work no problem. So now I'm fresh out of ideas. I was hoping it was the water pump as that would have been easy to fix...

My 2002 WRX began overheating today. My coolant was low, so at first I thought that was the problem. After filling it up and driving home, the temperature was still in the red. There is no visible leaking so I'm guessing it's not a hose problem. I took the cap off the radiator and started it up but didn't see any flow. The fans do come on. It overheats both when driving and idling. I'm thinking this is a water pump problem or a head gasket problem but I have no idea how to check for either. Any tips?