well the head was done a few months back but ive noticed a few little deposits of sludge in the header tank,its real greyish white and forms on the lid..ive flushed the system quickly but i still get a bit after a bit of driving.there is none in the oil,im not losing oil or water,its not getting hot and ive had it pressure tested and it held pressure well.
could this still be old stuff from when the head went?
cheers

Give the whole system a full flush and replace with new coolant. Most likely just old deposits from before the head gasket was done. Dont forget to flush your radiator too!

You will need to put a chemical flush through it.....then, thoughorly flush the system, and just put water in it for a couple of days, see how it goes, if all good, then flush with water and refill with coolant.

cheers for the tips guys