Just keep your tonge over the hole & block it the second you feel fluid, it gets more difficult as the water comes to the top but it's about the best way to get the air out, only take a minute & may save you from overheating.

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Beaten up old 98 Gen 2 Liberty, 13.0, stock V3 STI running gear.
07 Transit motor home
69 VF & 70 VG Valiants needing full restoration
Yamaha Zooma 50cc rocket hopefully going with the Transit.