Probably an air lock, try squeezing the top hose quickly a dozen times or so then take the cap off & fill, repeat this until the hose is too hard to squeeze, works for me. The smell will probably be from spilled coolant sitting in the exhaust covers......or a loose hose clamp.

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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.