It seems to have been some BS and misunderstanding from the mechanic in this case. Things does not look as bad as it was stated in the first place. We will start repairing the HGF first, and then go over the cooling system at the end of the repair for fault finding.
I have started a new thread for the HGF repair:
http://www.the75andztclub.co.uk/foru...52#post1226752