17 11 100 Removing and installing/replacing coolant expansion tank Z3/M54/S54

WARNING: This page is about a different car, the 2002 BMW Z3 and 2001 BMW Z3. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Danger of scalding! Open cap on coolant expansion tank only after engine has cooled down.

NOTE: Follow instructions for working on cooling system. Refer to 17 00 ...INSTRUCTIONS FOR WORKING ON COOLING SYSTEM. .

Recycling

Catch and dispose of escaping coolant.

Observe country-specific waste-disposal regulations.

Drain off coolant only down to lower edge of coolant expansion tank, refer to 17 00 005 DRAINING AND TOPPING UP COOLANT .

Release clamp (1) and detach vent hose (2) from coolant expansion tank.

Fig 1: Detaching Vent Hose From Coolant Expansion Tank

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Release screws.

Release diagnosis socket (3) and place to one side.

Release clip (1) and detach water hose (2).

Fig 2: Removing Clip And Detaching Water Hose

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Release clip (3) and detach water hose (4).

Remove coolant expansion tank.

Installation:

When installing coolant expansion tank:

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

Fig 3: Inserting Locating Pin Into Locating Bore

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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.
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.

Fig 4: Closing Vent Plug

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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 O.K. 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 5: Identifying Max And Min Markings Of Coolant Expansion Tank

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NOTE: The tank mark indicates the fluid level at approx. 20°C. Use only recommended coolant.