1711 100 Removing and installing/replacing coolant expansion tank Z3/M54/S54: Installation:

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

When installing coolant expansion tank:

Insert locating pin (1) into locating bore (2).

Fig 1: Installing Locating Pin

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To ensure the cooling system is properly vented, it is absolutely essential to follow the steps below:

Open cap on coolant expansion tank

Fig 2: Opening Cap
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Turn on ignition.
Set heater control to maximum temperature.
Set blower to low level. This opens the heating valves and starts the auxiliary water pump.
Perform filling operation slowly.
Close vent plug (1) when bubble-free coolant emerges
Pour coolant into coolant expansion tank up to max. cold fill level. Marking (2) is then level with upper edge of coolant expansion tank.
Close coolant expansion tank.
Allow engine to warm up until thermostat opens.

Allow engine to cool down before checking coolant level. Coolant temperature must not exceed 30°C. If ambient temperature exceeds 30°C, allow engine to cool down at least to ambient temperature.

Carefully open sealing cap and check fluid level. Fluid level is OK. when top edge of coolant expansion tank lies between both markings (1 and 2) on float needle.

Minimum cold fill level:
Top edge of coolant expansion tank is level with marking (1)
Maximum cold fill level:
Top edge of coolant expansion tank is level with marking (2)

If necessary, top up coolant.

Fig 3: Identifying Cold Fill Level
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NOTE: The tank mark indicates the fluid level at approx. 20°C. Use only recommended coolant.