Thanks. Coolant etc all good. The crusty pipe on the thermostat is old leakage from X years ago. Seems to happen to these.If you think the earth made a difference, try cleaning it more - it may be what was done made a difference, but more needs to be done to make the difference last!
Experts once knew nothing, they now know something, because someone told them, showed them, or they did until they did it right. Soon, you'll be an earth expert!
Crusty liquid? Milky coolant / oil?
Off to become an expert in something or other!