Thanks guys. David, I got one of those vacuum filler kits based on feedback here.
So my problem was two problems at once.
The heater valve was probably just not tightened enough. After removing and replacing it 5 times I finally realized that the air I was hearing escaping was from the thermostat to swirl tank hose which is close enough to the heater shut off that that's what I thought I was hearing. Holding steady pressure now!
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