[my4dv8]

So with an overflow tank on a non pressurised system , once the bottle is full it simply overflows on to the pavement. To me an overflow tank on a non pressurised system seems pointless , apart from looks. I suppose it could return to a non pressurised system as long as the overflow pipe in the radiator was submerged. What is the trick to getting say a 4lb pressurised cap on an A so in fact when it cools it will actually return to the radiator .