So I've sprung a leak on my 53 blob

Appears to be from the bottom of the rad drivers side, I say this because I can see a pool of coolant on the under tray in the location.

I can't actually see a leak, I think the leak only occurs when under load, on idle all is well.


How can my rad suddenly start leaking though? Is that something that really happens? Its not exactly a old rusty radiator?

Checked hoses nearby and bottom rad drain and all are tight and appear free of breaks. Rad hoses are no longer standard and have been changed for samcos.