I've got a '67 wagon that I've had for a handful of months and am looking at getting roadworthy again. Mostly basic stuff. Idler arm, breaks, etc. I'm having trouble with the cooling system. The previous owner didn't have a gasket inside the radiator cap. I've since replaced the radiator cap and thermostat and flushed the the cooling system.

It's still overheating and I'm wondering if there's a problem with the temp gauge or sender. The gauge will show the car heating up gradually, but the gauge eventually registers all the way in the red. Is this a common failure mechanism for the temp gauges? I've never worked with ether based temp gauges before. Are there any tricks to ensuring that all the air is burped from the system?

Thanks for your help!