Thank you all. Yes those tappets did quieten down once it was throughly warmed up. For the eagle eyed you may have noticed the coolant colour. I ran it with water and 50g of citric acid in to clean out any unwanted guff from the cooling system. I've a PRT thermostat arrangement to fit as well so I'll flush out the system, refill and drain again to remove any citric acid residue and fit the PRT and refill with OAT Coolant/anti freeze.