A body-shop employees Vectra snaps its chain biffs the valves, engine gets stripped of its head this gets sent away for pressure testing passes OK. New chain kit fitted, new valves and the head refitted stared OK and everything runs sweet. Road test carried performance is good, coolant level checked when back at the garage and guess what the tank is low, but the missing coolant was found in # 4 plug hole thats the 3rd case of this weve had in our garage. Even with no plug in and the system pressurised we cant pin point the exact location of the leak only that if you look down the hole its in the 1 to 2 o`clock position. Needless to say an exchange head is on order.