Cooling Issues

Please tell us about the cooling pipes underneath the car.

were they replaced, removed and cleaned, left in place with no inspection?

Have you confirmed both fans are still operating correctly?

Larry

Seems you have a handle on the problem. The most likely culprits are air in the system or a thermostat that’s not working as it should anymore. Try filling the cooling system with a vacuum filling device. Also, make sure you get a real 351C thermostat. I know tmeyer sells them.
Good luck!

So yes the cooling pipes were replaced and both fans are working. Yes I have the correct thermostat and the "washer/restrictor" in line.

I concur with David that the problem could be air in the system.  A healthy cooling system in a Pantera can appear problematic if all of the air is not purged. There are several ways to purge air from the system.

If there is a vent line and undercar vent tube from the top of the radiator check it is not blocked. All the sediment drops into the lowest point and that skinny little tube will get blocked. Then no venting and a problem.

Problem found. When I took off the engine cover i found the water pump belt was loose. Ill test drive it tomorrow but i'm pretty certain this was the problem. Thanks for all the input.

Strange you didn't hear anything.

That belt drives the alternator as well.  Did you have any charging problems or was the battery low?

Fingers crossed that the fix is that simple

Larry

As a precaution when the car is cold take the radiator cap off and look inside the swirl tank with a flashlight.  The water should be at the very top.  If not then air is in the system and/or there is some other leak.

Also, make sure there is water in the overflow tank.

With the cooling system cold, the swirl tank should be completely full and the overflow tank should be about half full.

John