2003 Malibu Overheating

After driving hour or so I get overheating signal "radiator picture light on dash", indicating radiator water is low. Water is low in water fill tank. From cold start, ran engine with fill container cap off. The car ran for awhile (10 to 20 minutes), but I didn't see the water move (temp gauge went passed halfway point, where it usually is). If I give it gas during this time, water comes gushing out where cap belongs. This may not be due to water pump...? or is it? Is it only in radiator that you can see water move? Also, where is the thermostat...I would like to test it. Can anyone help with overheating problem? Thanks in advance.

Joe

After driving hour or so I get overheating signal "radiator picture light on dash", indicating radiator water is low. Water is low in water fill tank. From cold start, ran engine with fill container cap off. The car ran for awhile (10 to 20 minutes), but I didn't see the water move (temp gauge went passed halfway point, where it usually is). If I give it gas during this time, water comes gushing out where cap belongs. This may not be due to water pump...? or is it? Is it only in radiator that you can see water move? Also, where is the thermostat...I would like to test it. Can anyone help with overheating problem? Thanks in advance.

Joe

Thanks, but no thanks
Due to no response from this site I brought the car in for repair. The mechanics found an open fuse had stopped the fan. I never noticed that.
There you go, don't forget your fuses...

Joe