[Tony Alonso]

Originally Posted by Hicompression

Yep, sounds like you had an air bubble in the system. There is a plug in the coolant crossover on top of the engine that is supposed to be taken out to "burp" the system when changing the coolant. Sounds like this may not have been done.

Thanks for the info. It's been awhile since I've looked at these engines, and I had forgotten about the plug. Oddly enough, when I had the coolant changed at a dealership on my first Mach 1 back a number of years ago, I had the same thing happen. Perhaps that wasn't done then either.