Swirl pot/header tank issues??

[fullthrottlehyde]

So quick question, just recently got a 3000m. I don't know if this is standard but I have a quite basic pressurised radiator system with a main swirl pot and overflow system. I have replaced all the hoses and the water pump works fine, I have filled the swirl pot and the overflow( to half way) but when I start and run the car water comes out the top of the swirl pot even before it comes up to temp, it has a brand new cap aswell. Do these normally leak? I can't see any reason why it should, just for information the thermostat seems to work and water gets round the system as all the pipes are hot, just throws water out the top of the header tank/swirl pot etc



Any suggestions?

[fullthrottlehyde]

I have a blanking cap on the swirl pot and a pressure cap on the overflow

[fullthrottlehyde]

On the blanking cap, underneath it's a solid piece of rubber, this sounds like it could be wrong. What should the double seal item look like and why do the 2 seals make a difference?