Hi Ed,

 

for sure I saw your installation before (numerous times...), but I do not recall your exact pluming.

Your description below sounds like inlet and outlet are facing down.

At 22psi it should even be more like 1/2 the radiator with air :)

Anyway, I assume waterflow is radical enough to strip the air out in 3 trials.

My system will have a bottom inlet and a top outlet. If it doesn't fit the outlet may exit the bottom of the tank but will have an internal standpipe - this way there is next to no space where air can get trapped, just a small bubble atop the standpipe, won't be big enough to cause any cooling detriment.

I still see BMW motorcycle oil-coolers mounted this way. Don't know the exact make-up today, but the earliest ones where simple single pass bottom feed bottom exit (cheapest solution and esthetically least disturbing), a big problem to purge. 1/4 was useless because of trapped air...

Furthermore, if the pump had a little leak or just a long time between runs would drain the oil fro mthe cooler and at start-up you had a fresh load of cold air inthe cooler! As it heats up the air-bubble expands and reduces cooler volume even more...

 

Best Regards,

 

TJ

snipped..

 In my case, if I do a complete drain and refill of the system, on the first run up the core's tanks  will be hot approx 2/3 of the way up and then they are much cooler - indicating that the remaining 1/3 of my core is filled with air.  It generally takes me 3 runups reaching 5000 rpm before I can touch  the core tanks and find them hot all the way from top to bottom.  So depending on your radiator set up that might be something you can quickly check.