2004 Concorde overheating
 

Good morning,
My grandparents which are still driving (age 96) drove to Tampa from daytona and there car overheated. They allowed the car to cool and we then drove it to the house. When we arrive again the car was hot so I removed the reservoir cap carefully and with the engine running, attempted to add water. I noticed both electric fans did cycle on while I added water. The water in the reservoir bubbled violently and really would not allow me to add much water before overflowing. I allowed the hose to run overflowing the reservoir but the water never calmed down and kept boiling. The temp never really reached more than mid between hot and cold while I allowed the water to run overflowing the reservoir.

I put the cap back on and the temp began to rise again.

I am open to any suggestions on what might be causing the overheating. Car has approx 60,000 easy miles and has never overheated before. I checked the oil and did not see any water as well as checked the exhaust and again, dry ov no water.

Look forward to any suggestions this forum can provide.

What Engine ? Must bleed air out when filling coolant.
Cooling systems today depend on both correct mixture of anti freeze and pressure to prevent "after boil"
Obviously check for leaks. Cap, resivoir, etc.
If all is OK, have seen thermostats fail closed. OEM stat has a rubber ring/ seal that swells with age.
If it is a 3.2 or 3.5 it is overdue for timing belt/water pump if not already done.
Head gasket is the ultimate last thing with these engines to cause overheat. Check everything first.

Ok, I'll start with bleeding the air out considering it did not over heat here at the house when I ran it for 20 + minutes with the cap off and water running from hose into reservoir

How do I bleed the air out?

Update: found the bleed valve and it was frozen and will not open. Opened the reservoir and filled with water and replaced cap. Ran car at 2500 RPM and then drove 70+ miles an hour for 20-30 minutes including getting in stop and go traffic. Now car will not over heat. I'm now guessing but may my grandparents drove here and the water level was low in the radiator? Most of the drive is highway and when they got in traffic the restricted flow of air from the highway now allowed the car to over heat?.. Any thoughts would be appreciated.