Genuine BMW Coolant Expansion Tank B48/B58 F20 F21 F22 F23 F30 F31 F34 F32 F33 F36 1/2/3/4 Series 120i 125i 220i 230i 320i 330i 340i 420i 430i 440i M140i M240i OEM Reservoir/Header Tank - Part No 17138677649

BMW B48 B58 Radiator Overflow Bottle - OE Cooling Reservoir - Part No 17138677649

Keep temperatures stable and reliability high with the original BMW cooling reservoir for B48 and B58 powered F Series cars. This OE radiator overflow bottle, also called a degas tank, surge tank or antifreeze header bottle, is a direct swap that restores leak free performance and stops low coolant warnings. Part number: 17138677649.

We fit this unit on our own fleet and for customer builds at MJ Modifications. Feedback has been consistently positive for fitment, quality and long term durability under daily use and spirited driving. If your current bottle is yellowed, cracked, weeping at the seams or you keep smelling coolant under the bonnet, this is the smart fix before small issues turn into overheating.

Why it is the right choice

• Genuine BMW component - OE specification, perfect alignment with factory hoses and mounts
• Direct replacement - no modification, no guesswork, plug and play swap
• Built for pressure and heat - ideal for stock, tuned and track driven cars
• Stops coolant loss and warning messages by replacing aged plastic
• Maintains proper cooling system operation and helps protect your turbocharged engine
• Trusted by enthusiasts - proven in our workshop with excellent customer satisfaction

Vehicle fitment - B48 and B58 petrol models

For F Series 1 Series, 2 Series, 3 Series and 4 Series with 2.0 and 3.0 TwinPower engines. Typical applications include:

• 1 Series F20 F21 - 120i, 125i, M140i, xDrive variants
• 2 Series F22 F23 - 220i, 230i, M240i, xDrive variants
• 3 Series F30 F31 F34 Gran Turismo - 320i, 330i, 340i, xDrive variants
• 4 Series F32 F33 F36 Gran Coupe - 420i, 430i, 440i, xDrive variants

Not sure if it suits your exact car? Add your UK reg or last 7 of VIN at checkout and we will confirm compatibility before dispatch.

Common signs you need a new tank

• Coolant smell in the engine bay after a run
• Intermittent low coolant messages or frequent top ups
• Cloudy, discoloured or brittle plastic bottle
• Visible seepage around joints, hose connections or the level seam

Part number

BMW 17138677649 - original equipment radiator overflow reservoir for B48 and B58 engines in F20, F21, F22, F23, F30, F31, F34, F32, F33 and F36 chassis.

Professional fitting

Installation available at MJ Modifications in Warwickshire. For a fitting quote or workshop availability, email info@mjmodifications.co.uk.

What you get from MJ Modifications

• Genuine BMW cooling system hardware with factory reliability
• Fitment check using your registration or VIN
• Fast dispatch and knowledgeable support from BMW specialists

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