Cooling system purge

Max162 said:

Hello all, I have a question regarding the cooling sytstem.

While doing some maintenance on my 54 Super Wasp, I noticed that the coolant level was low inside the radiator. I did filled it, but in order to complete the job, I must get rid of any air that is inside of the system. Though the shop manuals seems to not tell anything, I'm wondering if there is a way to purge it, as I don't want to have the engine overheat because of any air bubbles in the cooling system.

I'll be also checking if it's not something else I can do in the meantime.   

If you look at the design of the radiator, you'll notice it's somewhat like a cathedral roof. This is intentional, as the top 1" of space in the rad is there for expansion.  Back in the day, they didn't use expansion tanks - as the top of the radiator is exactly that.   

The system is self purging, as air seeks the highest point - and - the top header is WAAY above the head in a Stepdown Hudson.  There's no need to worry - fill to 1" below the top, and wait for the air to bleed out.  Takes a few minutes.  Then refill to 1", repeating as necessary, which should only be 1-2 times.  If you want to speed this up, drill a 1/8" hole in the thermostat as an air bleed (assuming it doesn't have one already).  

My brother and I were involved with heat transfer and automotive cooling systems early in our careers.  The issue with purging has to do with modern radiators being lower than the high point in the system, allowing air to puddle in the head and restrict flow.  An air pocket in a head will eventually purge, but there is risk of damage - but that's only on cars after about 1988.  Prior to that - they were all self purging, to the best of my knowledge.  Since Hudsons predate 1988 by 34 years at a minimum - you 've nothing really to worry about.