A mate of mine has a 300tdi which has stood idle for some 5 years. He has now been using it regularly for a few months. A few days ago he found a puddle of coolant beneath the vehicle. I replaced his water pump and p-gasket. Yesterday he called telling me that he has observed some coolant leaks from the areas surrounding the hose clips and that there was pressure in the coolant, 2 hours after the engine had been turned off. I am suspecting HGF. He is a bit more hopeful and is blaming the radiator cap. Any suggestions?