BMW 3 Series E46

since 1998 release

Repair and operation of the car

BMW 3 Series E46
+ BMW 3 cars (E46)
+ Current leaving and service
+ Engine
- Cooling systems, heating
   - Engine cooling system
      Replacement of cooling liquid
      Check of a thermoswitch
      Check of the cooling system under pressure
      Connection and separation of the quick disconnect coupling
      Removal and installation of the thermostat
      Removal and installation of a fan / casing of the fan
      Removal and installation of the fan with the viscous coupling
      Removal and installation of a radiator
      Removal and installation of the pump of cooling liquid
   + Heater and conditioner of air of salon
+ Power supply systems, injection and release
+ Engine electric equipment
+ RKPP and transmission line
+ Automatic transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment
+ Schemes of electric equipment

Engine cooling system

Scheme of a contour of cooling


1 — a radiator 2 — a broad tank 3 — heating of salon 4 — the thermostat 5 — the pump of cooling liquid	6 — the block of cylinders 7 — return 8 — giving 9 — heating of a butterfly valve 10 — the heater crane

Cooling system elements


1 — a radiator 2 — the lower hose of a radiator 3 — the top hose of a radiator 4 — a radiator stopper 5 — the water pump	6 — the thermostat 7 — the thermostat case 8 — a krylchatka of the fan of a radiator 9 — the viscous coupling

The engine is equipped with the circulating cooling system. Until the engine is heated-up, cooling liquid circulates only in a head and the block of cylinders and at the open crane of a heater in the heat exchanger of a heater of salon. At increase of temperature of cooling liquid the thermostat opens a big contour of cooling. Cooling liquid goes through a radiator constantly working pump. There is an innovation at petrol engines consisting in so-called cooling according to characteristics. At the same time the control system of the engine regulates temperature of opening of the thermostat and optimizes, thus, engine temperature by criterion of fuel consumption.

Cooling liquid is filled in through a broad tank which is located sideways at a radiator and serves as capacity for liquid. It compensates the liquid expansion arising owing to its heating and gives the chance to it to decrease in volume after cooling of the engine.

For increase in efficiency of cooling in system the fan operated depending on temperature is installed. At increase of temperature of cooling liquid to +93 °C the thermoswitch connects the fan via the relay. If temperature of cooling liquid falls below +89 °C, the thermoswitch switches off the fan again.

The fan of a radiator can turn on at the idle engine. Owing to existence of thermal stagnation in a motive compartment it can repeatedly occur. Therefore when working around the fan wait until the engine is cooled.

320i, 323i, 328i with the conditioner: For increase in efficiency of cooling on a shaft of the pump of cooling liquid the additional krylchatka is established. In a nave the viscous coupling settles down. As soon as the air going from a radiator reaches temperature of +90 °C, the bimetallic plate in the viscous coupling connects the fan. The fan rotates with turns of the engine and provides a necessary consumption of air until temperature of the cooling air does not fall to value of +60 °C. After that, the viscous coupling is switched-off and reduces fan turns. Owing to changeably working fan the useful power of the engine increases and fuel consumption is cut.

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