The bleeder valve is on the thermostat housing and is brass. It looks like a small bolt in a bolt with a small hole drilled into the side of the larger one. The thermostat housing is the outlet to the upper radiator hose. If the engine is cold just pop the radiator cap off and see if it's full and make sure the overflow is full as well and keep it full. It will go empty and you will end up with air in the system again. You could even have a stuck thermostat that is only allowing a small amount of coolant to pass. I answered a thread where I explained how the system works I will try to find it.
Jeff
