Cooling system specifications (BMW 5 Series E12)

The cooling system is liquid, with forced circulation of liquid using a centrifugal pump. On cars of the "525" and "528" models, an expansion tank with drainage through a drain pipe is installed.

Radiator

The radiator is a tubular-plate type with a safety valve built into the filler plug.

Opening pressure of safety valve, kg/cm²:

• when pressure increases: 1^+0,15_-0,10.
• when pressure decreases: up to 1.0.

Fluid flow through the radiator at a pressure of 0.5 kg/cm², l/h: 20.

Test pressure, kg/cm²: 1.5.

Thermostat

Brand:

• "518", "520", "520i": Wahler;
• "525", "528": Behr.

Temperature of the main valve opening start, °C: 80±1.5 ("525" and "528": 84).

Main valve piston stroke, mm: 8±1.

Since model year 1978 on BMW "518", "525", "528i" with automatic transmission, "520" and also on "520i" since 1982 model year, the temperature of the beginning of opening of the main valve is 80°C. On BMW "518", "525" and the "528i" with a manual transmission it is 84°C.

Fan

Viscous coupling brand ("525", "528"): Fichtel und Sachs (Holset since 1978 model year).

Fan drive belt brand:

• "518", "520": Venfiflex 1106;
• "520i": Vcntiflex 1112;
• "525", "528": Aatbeit 2212 DA.

Water pump

The water pump is of the centrifugal type.

The gap between the pump body and the impeller, mm: 1±0.2 (for "525" and "528": 0.9±0.2).

Since the 1980 model year, the gap between the impeller and the pump housing for the BMW "518" is 0.4-1.2 mm, for "525", "528i", "535i" — 0.7-1.1 mm.

Since the 1982 model year, for the BMW "518/E28" it is 0.8-1.2 mm, and for the BMW "520" and "520i" with a six-cylinder engine - 0.4-0.8 mm.

Coolant

Capacity of the interior cooling and heating systems, l:

• "518", "520", "520i": 7,2;
• "525", "528", "528i", "535i", "520" and the 520i with a six-cylinder engine: 12.0.

Coolant used: a mixture of distilled water and antifreeze (at temperatures down to -25°C).

Replacement frequency: every two years of operation.