Lube system purging

So my takeaway is don’t mess with the cap, let it leak whatever air that escapes, just set my regulator to deliver between 5.8-15.0 psi to the tank via the vent nipple and disregard the actual resulting pressure inside the tank- which was about 4 psi for my tank- and turn the prop by hand until a rise in oil pressure is noted. Would be helpful if the SI and IM clarified the pressure inside the tank is irrelevant to the procedure.

Correct Jim. 

I understood (?) that you are following the correct procedure but losing so much air out of the cap, that the pressure within the tank is negligible (unable to help the oil start circulating) - if this is the case, some aspect of the cap is worn, likly the seal.

The loss of air out of the cap is part of process but too much loss will defeat the process.

One way to see how good you are is to have someone turn the power on while you’re rotating the prop and see what kind of oil pressure you’re generating. I usually get 50-55 psi while ding an oil purge.

4-5 psi should be good enough to get your oil to the pump.