Knocking sound in Ford Territory

My 2007 Ford Territory has a knock that seems to be coming from the engine bay when the vehicle is started from cold. Once started, it will not happen again until the motor is once again cold. This has occurred since the vehicle was new. I have taken it to the dealer three times and they say they can't find the fault. The dealer told me that it is a trait with the Territory. I live in Adelaide, so I rang Ford Australia in Victoria, and they more or less brushed me off saying they had no other reports of this problem. The vehicle has only done 25,000 km and I am concerned that this may cause a problem later.