Genuine BMW part 11 51 7 515 852: Torx screw. The number stamped on the part is 11517515852; BMW's catalog files it under the short number 7515852. You will find it on our Engine shelf, under Coolant pump with drive.
It fits every E46 body style (316i, 316ti, 318i and 318ti, 2001–2004), with the N40, N42, N45 or N46 engines.
BMW draws it on 3 diagrams, among them Waterpump - Thermostat (11_3192) and Power steering pump (32_1284). BMW's catalog calls for two of these at each place it is fitted. It weighs about 10 g (under 0.1 lb).
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.