Herald 1200 Still pushing 1 pint of coolant out every journey of more than 5 miles

[Colin Lindsay]

19 minutes ago, johny said:

When you say washer Colin its a reverse valve in the centre with its own spring which is pulled open by vacuum in the radiator. Im not sure any caps are produced now without it as of course its perfectly ok for use in a non reservoir set up...

I should have said 'sealing washer'; basically the two types are the same but one needs to seal so the vacuum draws fluid back in, not air; the other doesn't. I don"t think there's any difference in the depths of the cap in this instance, and although the two types in the photo seem to have a different profile of 'sealing plug' on the end of the spring, I think that's down to supplier not any kind of engineering requirement. I think! Heralds are an everyday learning process.

 

[johny]

Hmmm well looks like both types have the vacuum valve in the centre but as you say cant pull coolant back unless the top face in sealed. Maybe the vaccum release valve has always been incorporated just to avoid the risk of ending up with negative pressure in the system whatever its set up....