Help overheat (not degas bottle/thermostat)

[DocD25]

Hello All,
I have an 02 Lincoln LS, last year it overheated on me, I changed the thermostat, and I also changed the Degas Bottle because that turned out to be the problem after doing my research on this forum, and the car has been running like a champ every since, until the last few days. The New problem is it seemed like my heater was not working or it would be very hot then very cool then finally get warm and stay that way. Then tonight I had to run out to a buddy's house about an hour away and the car ran out no problems at normal operating temp, once I got to my destination I heard the fan howling away and the temp gauge began to rise. Then on the way home same thing normal operating temp soon as I stopped at my house it started to rise slowly. Any ideas, I am thinking maybe the water pump is going bad but not sure how to check for this. Any assistance you guys could provide would be greatly appreciated. Since I have taken ownership of vehicle maintenance has been pristine, I checked oil it is absolutely beautiful no signs of possible head gasket issue there, no loss of power I am clueless at this point.

 

[joegr]

All the plastic cooling system parts should be your first suspect, starting with the cooling tower and radiator hoses. While it could be the water pump, they seem to be pretty reliable, so I would save that for last.
Your DCCV should also be suspect. Sometimes they do leak and let air into the cooling system. Yours is suspect because it sounds like it is starting to fail anyway.
Check your aux pump and radiator as well.

 

[DocD25]

How would you check for aux pump failure? Second I did open bleeder tube last night and a steady stream of coolant came flowing out, and it was warm not hot, like I thought it would be after just coming back from an hour drive.

 

[joegr]

How would you check for aux pump failure? Second I did open bleeder tube last night and a steady stream of coolant came flowing out, and it was warm not hot, like I thought it would be after just coming back from an hour drive.

Sounds like the heater loop isn't really circulating. That is probably due to trapped air.
Aux pump failure would be indicated by having little to no heat at idle, but good heating at highway speeds. More important than failure though would be to check it and make sure it isn't leaking. Look for dried white or orange water spots everywhere. When you find some, your leak is probably near by.