Cooling system problem!

[Maz_uk]

I checked the coolant in my 4.5 Cerb the other day and thought "This looks low"

Anyway a litre of water/coolant later I think I'm done.

Then I go for a blast, temp was sky high compared to previous and steam from under the bonnet!

Anyway I need to reduce the coolant level and make sure there is no air in the system,.

Best way to do it?

Thanks