DNSDC said..
I've owned a few Hondas but I'm not real familiar with the Odessy. Check to see if the radiator cap is lower than the thermostat housing, if it is, the system may need bleeding to remove air trapped in the head. There should be a bleed screw on the thermostat housing, heat the engine up, open the bleed screw til water starts squirting out then close the bleed screw. It may help
if so, better to use a coke bottle (cut off bottom) like a funnel in the radiator cap, to get a head of water higher than the thermostat. Whilst mate fills coke bottle, open bleed screw until coolant comes out. That way it is full.
Yours relies a bit on water expansion when hot and you don't know just how "underfull" it is at the end
