Hello All.
I’m after some advice on header tanks.
I recently purchased and fitted an alloy header tank from Car Builder Solutions.
What radiator cap should be fitted to it? Should it be a valve-less one or one with a valve?

I have a Ford Zetec engine and believe it should be a sealed system.
On my previous installation I had a plastic header tank from a production car this had three outlets and was connected as such: The larger connection at the bottom of the tank was connected to the larger outlet on the Thermostat housing, the medium one was connected to the overflow bleed connection on the Thermostat housing. The third one was connected to the outlet in the radiator neck. This was working fine.
I connected the new tank up the same and put 13LBS pressure caps on both the tank and radiator, this caused the top (Medium) hose to start leaking at the connection with the tank.
If I remove the smaller hose going to the radiator the pressure drops. But then there is steam being released.
My thought is the pressure cap is stopping the flow from the thermostat overflow bleed from getting into the tank, but it needs to go somewhere I guess so blows the seal.
So should I fit two valve-less caps?
If I was to do away with the connection between the header bleed and the radiator neck, do I just blank off both outlets?
Thanks for any advice, sorry for the essay.

Hi Martin,

The cooling system on my zetec is sealed.
The header tank has two connections. The bottom one goes to the bottom radiator hose and the small top connection is connected to the small outlet on the thermostat housing.
I'm using a VW302 rad which doesn't have a cap.
The rad does have a small connection near the top hose but this is blanked off.

So I guess in answer to your question you need to put two valve less caps on to seal the system.
I am no expert on this suject and therefore can't be held responsible for you being blown out of your garage if the whole thing goes kerbooooom!

If your existing setup worked then I would make the new header the same 'spec' as the plastic one you took off i.e. fit a non vented cap if this is what the plastic one had, if that makes sense.

Hope to see you at the meeting.

cheers
Stu.