mealmond

Final update I hope.
I decided to take my car to my normal garage and ask them to flush the matrix for me. I felt they would be able to sort it quicker and better than I could.
Net result is after a very good and intense flushing including a stream pipe, I have lots of heat, in fact it's too warm ????????
Lots of crap came out and like I thought there is every chance some sort of radiator sealant had been used in the past.
I had it flushed last year at another garage and I asked them to flush the matrix as well, I thought they had but obviously not.
Thanks for all the help but most of all thanks to Wino for all the help and advice you gave have me, including disecting a matrix. If you had not asked about the pipes being warm, I would have replaced the flap motor.
I feel confident the issue is sorted only because I know lots of rubbish came out of the matrix.
Watch us have a mild winter now.
Martin