Cooling system:
A - until August 1979.; B - since August 1979.; C - on cars of the model "323i" produced since April 1981.
1 - water pump; 2 — pump shaft; 3 - retaining ring; 4 — impeller; 5 — oil seal; 6 - thrust sealing ring of the oil seal; 7 - water pump housing gasket; 8 — flange; 9, 20 — water pump drive pulley; 10 — radiator; 11 - expansion tank; 12 — expansion tank cap; 13 - drain pipe; 14 — connecting pipe; 15 — fan switch sensor; 16 — electric fan; 17 — fan; 18 — coupling; 19 — fan mounting flange; 21 — thermostat housing; 22 - thermostat; 23 — thermostat cover; 24 - Blow-off screw; 25 — thermal time relay ("323i"); 26 - thermoelectric switch; 27 — Thermoelectric switch 0°C (on "323i" since 1981 model year); 28 - oil cooling tubes (on cars with automatic transmission).
(The text is based on materials from the website «www.bmwman.ru»)