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BMW Coolant Expansion Tanks

On certain models, namely E36, E46, and E90, the factory BMW expansion tank is prone to either breaking at connection points or blowing apart altogether. If you're starting to feel like your expansion tank is on borrowed time, it's probably time to replace with either a direct OE replacement, or strengthen your cooling setup with an aluminum expansion tank - we offer numerous performance upgrades for your expansion tank. Especially if you're someone who likes to track your BMW, we recommend upgrading your expansion tank to avoid ruining your track day.
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ECS Tuning Aluminum Coolant Bleeder Screw
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ECS - Corporate Logo
T#:363070
Part#: 003530ECS01A
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This product was last offered at the strikethrough price on
06-13-2026

$ 26.99 USD
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Replace the flimsy plastic bleeder screw used in the coolant expansion tank or in one of the cooling system hoses with this high quality, durable, aluminum bleeder screw. The stock plastic screw can deform over time due to heat or even regular use. We have even seen the head of the screw snap off, leaving the threaded body stuck in the expansion tank. This aluminum screw will help to prevent sudden failure of the bleeder screw, which can result in immediate overheating of the car.

ECS Tuning's Aluminum Coolant Bleeder Screw replaces Genuine BMW Part Number 17111712788

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Bavarian Autosport - Corporate Logo
T#:638094
Part#: 17111723520
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This product was last offered at the strikethrough price on
05-03-2026

$ 31.99 USD
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This product was last offered at the strikethrough price on
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Replace your old expansion tank to prevent potential failure or leaks. Includes a brand new coolant level sensor. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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ECS Exact-Fit Silicone Expansion Tank Hose - F-Chassis N55
10X Entries Into Our F80 M3 Sweepstakes
ECS - Corporate Logo
T#:37892077
Part#: 006402LA03
In Stock
Sale - Save 30% $ 104.99

This product was last offered at the strikethrough price on
06-14-2026

$ 73.49 USD
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Over time, factory rubber hoses break down and eventually fail as a result of consistent exposure to chemical-rich antifreeze and hot engine bay temperatures. While all coolant hoses are prone to failure, the expansion tank hose is especially susceptible to failure. To fix this issue, ECS has created the ultimate performance hose upgrade! Crafted from heavy-duty, fiber-reinforced silicone, this ECS Exact-Fit Silicone Expansion Tank Hose withstands higher temperatures and greater pressure than the factory rubber alternative. Engineered to resist electrochemical degradation, it’s tested for continuous operation at 250°F and over 45 psi, ensuring improved reliability, enhanced flow, and reduced turbulence. To further improve upon the factory hose design, ECS engineers developed precision-machined billet aluminum "Quick Connect" hose ends. Unlike the OEM plastic counterparts, these robust components resist heat-induced failure, ensuring long-term durability and reliability. Replaces OEM Part Numbers: 17128570061, 17128507235. Installation is straightforward: begin by removing the factory overflow hose and retaining clips. Transfer the OEM metal clips from the factory connector to the new billet fittings, then press the fittings onto the expansion tank and upper coolant hose. The included silicone hose is routed through the OEM path and securely clamped onto the billet fittings. After installation, the fittings can stay in place, only the silicone needs to be removed for future maintenance. Key Benefits: Direct OEM Fitment – Retains factory hose routing while eliminating the weaknesses of rubber construction. High-Temperature Resistance – Silicone material withstands extreme heat and chemicals for long-term durability. 2-Ply, Fiber-Reinforced Fluorosilicone Construction – Provides superior resistance to glycol-based coolant and other harsh fluids. Upgraded Billet Aluminum Quick-Connect Ends – CNC-machined from 6061-T6 aluminum with integrated O-rings, ensuring a secure, leak-free connection that won’t degrade over time. Easy Installation – Includes stainless steel clamps for a hassle-free, bolt-on upgrade.
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Bav Auto Coolant Expansion Tank - E53 X5, E46, E83 X3
10X Entries Into Our F80 M3 Sweepstakes
Bavarian Autosport - Corporate Logo
T#:640496
Part#: 17137787039
In Stock
Sale - Save 18% $ 61.99

This product was last offered at the strikethrough price on
05-03-2026

$ 50.99 USD
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We have found that the expansion tanks should be replaced based on age as well as condition. Expansion tanks seem to have a lifespan of less than six years before they show signs of fatigue and wear. Pre-emptively replacing the expansion tank as part of an overall maintenance plan can prevent you from getting stranded from a sudden failure later on. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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Bavarian Autosport - Corporate Logo
T#:638088
Part#: 17111436250
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Sale - Save 20% $ 44.99

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05-03-2026

$ 35.99 USD
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This Bav Auto part is the mounting bracket from the radiator to the expansion tank on an E46 3 series with a Manual Transmission. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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BMW N47 N55 Expansion Tank
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Bavarian Autosport - Corporate Logo
T#:17704781
Part#: 17137642160
In Stock
Sale - Save 20% $ 98.99

This product was last offered at the strikethrough price on
05-03-2026

$ 79.19 USD
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BMW N47 N55 Expansion Tank from Turner Motorsport is a high-quality replacement designed to address issues with cracked or damaged coolant expansion tanks. Engineered for durability and performance, this expansion tank ensures reliable cooling system function.

  • Durable Construction: Built to withstand high temperatures and pressure, ensuring long-term reliability.
  • Direct Replacement: Engineered as a precise fit for BMW N47 and N55 engines, making installation straightforward and hassle-free.
  • Enhanced Cooling Efficiency: Maintains optimal coolant levels and pressure for effective engine cooling.
  • High-Quality Materials: Manufactured from premium materials to resist cracking and leaks.
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Bavarian Autosport - Corporate Logo
T#:638089
Part#: 17111436251
In Stock
Sale - Save 20% $ 45.99

This product was last offered at the strikethrough price on
05-03-2026

$ 36.79 USD
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This Bav Auto part is the mounting bracket from the radiator to the expansion tank on E46 3 series and E85/E86 Z4 with an Automatic Transmission. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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Bav Auto Coolant Expansion Tank - BMW E90 335d M57 3.0L
10X Entries Into Our F80 M3 Sweepstakes
Bavarian Autosport - Corporate Logo
T#:640493
Part#: 17138570079
In Stock
Sale - Save 20% $ 78.99

This product was last offered at the strikethrough price on
05-03-2026

$ 63.19 USD
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$ 78.99

This product was last offered at the strikethrough price on
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Replace your damaged expansion tank to prevent coolant loss or potential overheating issues. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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Bavarian Autosport - Corporate Logo
T#:638093
Part#: 17138621092
In Stock
Sale - Save 20% $ 60.99

This product was last offered at the strikethrough price on
05-03-2026

$ 48.79 USD
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Replace your old expansion tank to prevent potential failure or leaks. Includes a brand new coolant level sensor.

Bavarian Autosport - Corporate Logo
T#:640208
Part#: 17117639022
In Stock
Sale - Save 15% $ 13.99

This product was last offered at the strikethrough price on
06-03-2026

$ 11.89 USD
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This radiator expansion tank cap is used most BMW's from 1991-2006. It is a common failure item. When this item fails, it cannot hold pressure which results in your BMW overheating. If you are overhauling your coolant system, now is the time to consider preventative replacing this cap. It is also referred to as the coolant reservoir cap. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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Bav Auto Coolant Level Sensor - BMW E36 E39 M50/52 S50/52
10X Entries Into Our F80 M3 Sweepstakes
Bavarian Autosport - Corporate Logo
T#:639793
Part#: 61318360855
In Stock
Sale - Save 19% $ 20.99

This product was last offered at the strikethrough price on
05-03-2026

$ 16.99 USD
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This is the sensor / sending unit that notifies the computer if your coolant level is low. When this fails, it can give a false indication of low coolant -- or worse, not inform you of a low coolant situation that could potentially cause overheating. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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ECS - Corporate Logo
T#:56327169
Part#: 059178LA01
In Stock
New Item
Sale - Save 9% $ 407.99

This product was last offered at the strikethrough price on
07-23-2026

$ 369.99 USD
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07-23-2026

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Gen 2 MINI R5X models (R55, R56, R57, R58, R59, R60, and R61 chassis) utilize a closed, highly pressurized cooling system to maintain optimal engine operating temperatures. At the center of this system is the factory plastic expansion tank, which is constantly exposed to high heat cycles, vibration, and chemical-laden antifreeze. Over time, heat and pressure leach the plasticizers from the original material. This degradation causes the tank to turn brittle and yellow, eventually leading to micro-fractures, splitting along the factory blow-molded center seam, or catastrophic connection failure. Because coolant loss under pressure can occur rapidly, a failing stock tank frequently leads to severe overheating issues or unexpected roadside breakdowns.

This ECS Heavy Duty Aluminum Coolant Expansion Tank directly addresses the structural vulnerabilities of the factory unit by replacing molded plastic with a fully TIG-welded 5052 and 6061 aluminum construction. Aluminum eliminates the risk of seam separation, cracking, or heat deformation, providing a permanent solution that withstands continuous pressure and heat without expanding or fatiguing. To ensure precise fitment, the tank was engineered using 3D CAD modeling for a direct, plug-and-play installation in the factory location. No cutting, drilling, or custom bracketry is required to secure the unit.

All hose barbs, bleed points, and sensor ports are CNC-machined to precise tolerances, guaranteeing a leak-free seal with factory quick-disconnect hoses. A precision-threaded cap neck ensures smooth engagement with the expansion tank cap while maintaining an airtight seal against the internal cap O-rings. To simplify routine maintenance, an integrated external sight glass and internal level tab eliminate guesswork, allowing you to check your coolant level at a glance. Finally, the heavy-duty wrinkle black powder coat protects the exterior of the tank from oxidation and engine bay heat while providing a clean, OEM+ appearance.

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2 Pin Connector
10X Entries Into Our F80 M3 Sweepstakes
ECS - Corporate Logo
T#:33412932
Part#: 61132359999
In Stock
Sale - Save 25% $ 10.99

This product was last offered at the strikethrough price on
06-14-2026

$ 8.24 USD
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Includes connector housing with terminals and seals. Commonly used for the coolant level sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 61132359999 - Commonly used for the coolant level sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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Bavarian Autosport - Corporate Logo
T#:640491
Part#: 17137542986
Special Order: No Guaranteed ETA
Sale - Save 10% $ 54.99

This product was last offered at the strikethrough price on
05-03-2026

$ 49.49 USD
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This Bav Auto cooling system expansion tank/coolant reservoir is a direct replacement for the factory unit. Replace your cracked or leaking radiator expansion tank today. From 1974 to 2019, Bavarian Autosport was one of the premier vendors for BMW and MINI auto parts. We are happy to preserve the Bav Auto legacy by continuing to carry their high-quality products into the future. All Bav Auto parts will remain unchanged in design and sourced from the same OEM suppliers to ensure long-lasting reliability. We trust these parts, accessories, and upgrades so confidently that we back every Bavarian Autosport branded component with a 2-year warranty.
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