Firstly, only ever put cold water in a cold engine.
Secondly, even if you think the radiator is empty, only ever remove the rad cap when the engine is pretty cold.
Your thermostat has almost certainly gone, it's a 10-year-old car, so it was bound to go soon anyway. These fail in the "closed" position, so water ceases to circulate properly.
It's well-hidden on the Primera, but not impossible to replace by anyone who knows their way around the cooling system. It's a cheap part, probably will cost you less than a tenner (UK).
Secondly, even if you think the radiator is empty, only ever remove the rad cap when the engine is pretty cold.
Your thermostat has almost certainly gone, it's a 10-year-old car, so it was bound to go soon anyway. These fail in the "closed" position, so water ceases to circulate properly.
It's well-hidden on the Primera, but not impossible to replace by anyone who knows their way around the cooling system. It's a cheap part, probably will cost you less than a tenner (UK).
