I will soon be at the point of filling the new cooling system in my LS powered Healey. I'm thinking of rigging up a way to pressurize the DRY cooling system to 15 or so pounds and allowing it to sit with a gauge attached to check for any leaks. This would be the same as checking an AC system with vacuum. I have also saw AC systems pressurized with nitrogen to check for leaks before pulling a vacuum.

Anyone see any issues with this idea as long as I keep pressure lower than radiator cap pressure?

I'm running a separate expansion tank since the radiator is lower than the engine. I have a couple of places where it would be simple to introduce air pressure. I know that you can get radiator test kits, but they have small hand pumps and would take a long time to pressurize a dry system.