I had an overheating episode with this car when its radiator header top outlet snapped off (corrosion fault).
I stopped the car when I noticed the heat gauge needle was right up --it may have been like that a few minutes at very most--and the car was going well. After a long cool-off and replenished water etc the car started and went quite normally.
Cold start the next morning there was noise we had not had before--like a noisy hydraulic valve lifter. Anyway, with the oil slightly smelling burnt it was changed with a new filter and a can of STP added.
The car is not using water, oil is clean and it runs perfectly.
My problem is that while starting from cold the engine now has noisy metallic clunking for a few turns until oil pressure builds up.
What is this noise typically likely to be?
Any guidance will be very much appreciated.