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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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Enthusiast Bundles - Corporate Logo
T#:37419798
Part#: 008363LA02EB1KT
Ships on Dec 11, 2026
Sale - Save 24% $ 1,055.95

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

$ 799.04 USD
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Sale - Save 24%
$ 1,055.95

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05-05-2026

$ 799.04 USD
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Take your BMW’s cooling system to the next level with this Turner Motorsport Cooling Upgrade Kit. Featuring a Heavy-Duty Aluminum Expansion Tank and a Mechanical Thermostat Conversion Kit, this combo is engineered to deliver ultimate reliability and superior performance for M52TU/M54 engines. Say goodbye to the cooling system failures common in stock setups—Turner Motorsport has you covered.

Turner Motorsport M52TU/M54 Heavy-Duty Expansion Tank Kit

The Turner Motorsport Aluminum Expansion Tank is a premium upgrade designed to replace the fragile factory plastic tank, which is known to crack, leak, or even explode. Crafted for durability, this tank’s all-aluminum construction with wrinkle black powder coating ensures this is the last expansion tank you’ll ever need.

Why Upgrade? The factory plastic tanks on BMW M52TU/M54 engines are notorious for failure under heat and pressure. Avoid the risk of being stranded on the side of the road with a mess of coolant—Turner Motorsport’s aluminum expansion tank is built to withstand years of demanding use and intense heat cycles.

Key Features and Benefits:

Complete Kit: Includes Turner Aluminum Expansion Tank, coolant level sensor, expansion tank cap, and flared coolant pressure release line. OEM Fit & Capacity: Direct fit with no modifications, maintains stock coolant capacity and expansion volume. Baffled Design: Prevents air pockets during aggressive driving and ensures accurate coolant level readings. Premium Construction: TIG-welded 5052 aluminum with machined fittings for factory hose compatibility. Turner Motorsport M52TU/M54 Mechanical Thermostat Conversion Kit

Replace your problematic factory plastic thermostat housing with Turner Motorsport’s high-quality billet aluminum Thermostat Conversion Kit. This upgrade not only provides increased reliability but also allows for thermostat swaps to suit specific temperature requirements, making it ideal for daily drivers and track cars alike.

Why Make the Switch? The factory plastic thermostat housing with its built-in thermostat is prone to cracking and requires the whole unit to be replaced during maintenance. Turner’s conversion kit changes the game by providing a durable billet housing with a replaceable thermostat for flexibility and lower maintenance costs.

Key Features and Benefits:

Increased Reliability: Uses an M50/S50 mechanical thermostat, including an 80°C thermostat for enhanced cooling control. Customizable: Includes barbed hose connections for standard E46 M3 hoses and -16 ORB connections for custom hoses. Engineered to Last: CNC-machined from billet 6061 aluminum and black anodized for corrosion resistance. Enhanced Sealing: Features a Viton gasket for superior durability and sealing performance. Kit Includes:

6061 Billet Aluminum Thermostat Housing 80°C Mechanical Thermostat Thermostat Housing Gasket Thermostat Harness ECS Silicone E46 M3 Cooling Hoses Turner Motorsport Precision Engineering & Product Development

Every component in this cooling upgrade kit has been rigorously designed, engineered, and tested by Turner Motorsport’s Research and Development team. Using state-of-the-art technology such as FARO laser scanning, SolidWorks 3D modeling, and in-house rapid prototyping, Turner ensures that these products meet the highest standards of quality, precision, and durability.

Upgrade your BMW with confidence—Turner Motorsport is your partner in performance and reliability.

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Vargas Turbo Technologies - Corporate Logo
T#:7530033
Part#: COOLANTCAPBLK
In Stock
$ 79.99 USD
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$ 79.99 USD
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VTT is proud to offer their billet replacement for the factory plastic Coolant Reservoir cap. This cap does away with the weak plastic cap while adding some pop, and color to your engine bay. This coolant cap retains ALL of the factory provisions by simply allowing you to snap the factory pressure-relief into the new Billet Cap. VTT also designed these caps to complement their N5X Billet Oil caps, N5XBillet Oil filter housing caps, and Billet Power Steering cap, so all 4 will have the same design. These caps are offered in 4 colors – Red, Black, Blue, and Clear anodized Replaces Genuine BMW Reservoir Cap # 17117639020 Note: Fitment includes 99% of all BMW with a coolant Reservoir tank from the E series forward, meaning then fit even the brand New G8X M3/4 with the S58, all B58, etc. If your BMW is an E90 or newer this cap most likely will fit
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IND - Corporate Logo
T#:27572122
Part#: LVL.EN.22.326
Back Ordered
$ 618.99 USD
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$ 618.99 USD
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The coolant trap shield serves to stop antifreeze from the expansion tank from reaching the engine compartment and potentially causing damage to costly electrical parts, especially during periods of high fluid expansion. In the event of fluid splashing from the expansion tank, this shield intercepts it, guiding it through a designated outlet at the base of the trap for proper drainage. **Please note that this component is compatible with all North American models and European vehicles adhering to EU6c Emissions Standards (up to January 2021), but it is not suitable for Euro models meeting EU6d with RDE Level 2 standards.**
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Moroso - Corporate Logo
T#:568887
Part#: 63791
In Stock
$ 445.99

This product was last offered at the strikethrough price on
08-07-2026

$ 418.99 USD
Limited Qty Sale
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$ 445.99

This product was last offered at the strikethrough price on
08-07-2026

$ 418.99 USD
Limited Qty Sale
Free Shipping on orders $49 and up
If you have ever experienced a leaking plastic BMW expansion tank you will realize the value of this aluminum version straight away. Even if a failure has not happened to you, it's easy to tell this tank is much stronger and more durable than the plastic used in the stock design. The original BMW plastic tanks suffer from leaks and failures with no warning. While being lightweight and recyclable the design and construction of the stock tank is just not up for reliable long term use. Moroso coolant expansion tanks are all pressure tested for guaranteed leak-free operation and utilizes the stock pressure cap to prevent excessive pressure in the cooling system from blowing off a radiator hose or seal! Features: Each cooling system expansion tank includes a 1/8 in. pipe overflow fitting at neck, a 1/4 in. NPT water intake bung, and a 1/2 in. bung at the bottom for plumbing a line to the radiator Rugged 6061-T6 billet aluminum filler necks welded to tank to withstand continuous removal and installation of cap 100% pressure tested to eliminate leaks Accepts a standard-size radiator cap
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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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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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Precision Raceworks - Corporate Logo
T#:1332002
Part#: 201-0050
In Stock
$ 19.99 USD
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The E9X/ E8X coolant tank level sensor extension harness is the same great product that comes standard with Precision Raceworks' E9X/ E8X relocated inlet kits. The coolant tank level sensor extension harness is perfect for those running a relocated coolant reservoir tank or 335D coolant reservoir. This harness plugs right into the factory connector allowing you to extend the position of the sensor without the need to splice any wires.
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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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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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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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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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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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Vargas Turbo Technologies - Corporate Logo
T#:51848504
Part#: VTT-B58-CEBLUE
Ships in 10 Business Days
New Item
$ 59.99 USD
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$ 59.99 USD
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Elevate your BMW's engine bay while safeguarding your cooling system with the VTT B58 Expansion Tank Hose in Blue.

Vargas Turbo Technologies - Corporate Logo
T#:52164880
Part#: N54CLVTBLKO
Ships in 10 Business Days
New Item
$ 54.99 USD
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$ 54.99 USD
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The VTT N54 Upper Vent Hose is a critical upgrade for any BMW enthusiast looking to eliminate the weakest links in their cooling system.
Precision Raceworks - Corporate Logo
T#:38161691
Part#: 201-0393-SIL
Ships in 8 Business Days
$ 109.99 USD
Free Shipping on orders $49 and up

BMW Silver Engine Coolant Reservoir Cap is a premium upgrade for BMW owners looking to enhance both the performance and appearance of their engine bay. Crafted from high-strength billet aluminum, this cap replaces the factory plastic version, offering superior durability and a refined, professional look.

Designed with functionality in mind, it integrates the OEM pressure relief system to ensure your engine's cooling system remains safe and efficient. Unlike adhesive covers, which can peel or wear over time, this cap is a direct-fit replacement, providing a secure and leak-proof seal. The silver anodized finish not only enhances the visual appeal but also ensures resistance to corrosion, high temperatures, and wear, making it perfect for daily driving and track use.

  • OEM pressure relief integration – Maintains proper cooling system performance and reliability
  • Durable billet aluminum – Outperforms factory plastic caps in longevity and strength
  • Precision-machined for perfect fitment – Replaces the stock cap securely, not just a cover
  • Anodized silver finish – Offers corrosion, heat, and wear resistance
  • Elevates engine bay aesthetics – Adds a clean, professional appearance
  • Built for both street and track use – Designed to withstand extreme conditions

Enhance your BMW’s cooling system with the BMW Silver Engine Coolant Reservoir Cap, providing both style and functionality for years to come.

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Precision Raceworks - Corporate Logo
T#:38128031
Part#: 201-0394-BLK
Ships in 9 Business Days
$ 94.99 USD
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BMW Black Auxiliary Coolant Reservoir Cap is the perfect upgrade for BMW owners looking to enhance both the aesthetics and functionality of their engine bay. Unlike generic aftermarket caps that overlook critical pressure regulation, this precision-engineered cap retains the OEM pressure release functionality, ensuring safe and reliable coolant system performance.

Crafted from high-quality billet aluminum, this reservoir cap offers superior durability and resistance to heat and fluids, preventing warping or degradation over time. Unlike adhesive-based cap covers that can loosen or fall off, this cap is a direct replacement for the factory component, providing a secure, high-performance solution.

  • OEM pressure release functionality – Maintains proper system regulation for optimal coolant performance
  • Premium billet aluminum construction – Offers enhanced durability and longevity
  • Direct replacement design – Secure fit without adhesives or modifications
  • Resistant to heat and fluids – Ensures long-lasting reliability in extreme conditions
  • Performance-inspired look – Adds a sleek, high-end appearance to your engine bay
  • Upgraded durability – Prevents cracking, leaks, and premature wear

Upgrade your BMW’s cooling system with the BMW Black Auxiliary Coolant Reservoir Cap, blending performance, reliability, and premium styling.

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Precision Raceworks - Corporate Logo
T#:38128029
Part#: 201-0394-BLU
Ships in 9 Business Days
$ 94.99 USD
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BMW Blue Auxiliary Coolant Reservoir Cap is the perfect upgrade for BMW owners looking to enhance both the aesthetics and functionality of their engine bay. Unlike generic aftermarket caps that overlook critical pressure regulation, this precision-engineered cap retains the OEM pressure release functionality, ensuring safe and reliable coolant system performance.

Crafted from high-quality billet aluminum, this reservoir cap offers superior durability and resistance to heat and fluids, preventing warping or degradation over time. Unlike adhesive-based cap covers that can loosen or fall off, this cap is a direct replacement for the factory component, providing a secure, high-performance solution.

  • OEM pressure release functionality – Maintains proper system regulation for optimal coolant performance
  • Premium billet aluminum construction – Offers enhanced durability and longevity
  • Direct replacement design – Secure fit without adhesives or modifications
  • Resistant to heat and fluids – Ensures long-lasting reliability in extreme conditions
  • Performance-inspired look – Adds a sleek, high-end appearance to your engine bay
  • Upgraded durability – Prevents cracking, leaks, and premature wear

Upgrade your BMW’s cooling system with the BMW Blue Auxiliary Coolant Reservoir Cap, blending performance, reliability, and premium styling.

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Precision Raceworks - Corporate Logo
T#:47679257
Part#: 622-0291-BLAK
Ships in 9 Business Days
$ 184.99 USD
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$ 184.99 USD
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The Precision Raceworks Billet Coolant Cap Set is a functional and stunningly stylish way to add a nice touch to any engine bay! These caps come in three color options, so there is always a color that will work for you! Black with Billet Silver, Black with Blue, and the Stealth series (all black). Many people don't realize it, but the OEM caps have a pressure release valve built into them. Oftentimes, aftermarket companies don't know this either or just don't care. But our team cares about proper function just as much as we care about the appearance of every product we design. For pressure relief, our caps incorporate the OEM internals, so you get all the functionality of the original caps, ensuring a safe and reliable system in place. These caps offer superior style and performance-grade components that guarantee a reliable fit every time. Durable billet aluminum construction provides long-lasting protection and dependability that will upgrade your engine bay for years to come. PLEASE NOTE: These do require assembly and swapping the pressure relief valves from your old caps to your new billet caps.
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Canton Racing - Corporate Logo
T#:31423679
Part#: 80-272BLKKT1KT
Ships on Oct 20, 2026
$ 493.00 USD
Free Shipping on orders $49 and up

MINI R50 to R53 Expansion Tank / Power Steering Tank - Wrinkle Black Aluminum is a high-quality solution designed to address both coolant expansion and power steering needs in one kit. This kit includes a billet-style expansion tank with a radiator neck that accepts the Canton Racing part #81-030 pressure cap or any 30 psi radiator cap, ensuring a secure and leak-proof seal.

Key benefits of the MINI R50 to R53 Expansion Tank / Power Steering Tank - Wrinkle Black Aluminum include:

  • Dual Functionality: Combines both expansion tank and power steering tank into a single, convenient kit.
  • Durable Construction: Made from aluminum with a wrinkle black finish, providing long-lasting performance and a sleek appearance.
  • Enhanced Sealing: Features a billet radiator-style neck that fits standard 30 psi radiator caps, preventing leaks and ensuring reliable operation.
  • Reliable Design: Eliminates the issues associated with plastic tanks, such as separation and leakage.
  • Complete Kit: Includes a black expansion tank, black power steering tank, and a Stant cap for easy installation.
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Canton Racing - Corporate Logo
T#:19428688
Part#: 80-272BLK
Ships on Oct 20, 2026
17% off MSRP $ 272.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 227.00 USD
Free Shipping on orders $49 and up
17% off MSRP
$ 272.99

MSRP stands for Manufacturer's Suggested Retail Price. This is the suggested retail price provided by the manufacturer, supplier or seller.

$ 227.00 USD
Free Shipping on orders $49 and up

Upgrade your Gen1 Mini Cooper or Cooper S with the coolant expansion/fill tank featuring a billet radiator-style neck. This tank accepts the Canton Racing part #81-030 pressure cap or any 30 psi radiator-style cap. The Canton Racing Aluminum tank with Powdercoated Wrinkle Black finish not only enhances the engine bay aesthetics but also resolves expansion tank issues with its solid build and built-in mount. Say goodbye to concerns about separating and leaking plastic expansion tanks. Pair it with the Canton Racing 77-272 MINI power steering tank for a perfect combination.

  • Features a billet radiator-style neck
  • Accepts Canton Racing pressure cap or any 30 psi radiator-style cap
  • Enhances engine bay aesthetics with Powdercoated Wrinkle Black finish
  • Resolves expansion tank issues with solid build and built-in mount
  • Eliminates worries about separating and leaking plastic tanks
  • Perfect complement to Canton Racing 77-272 MINI power steering tank
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Canton Racing - Corporate Logo
T#:31390597
Part#: 80-272BLKKT
Ships on Oct 20, 2026
$ 265.00 USD
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MINI R50 to R53 Expansion Tank Aluminum Wrinkle Black & Cap - Kit offers the premium quality of Canton Racing for MINI enthusiasts. This high-grade aluminum expansion tank features a sleek Wrinkle Black powder-coated finish, designed to replace the original plastic tank with ease.

  • Premium Quality: Made from durable aluminum with a Wrinkle Black powder-coated finish for enhanced aesthetics and longevity.
  • Direct Replacement: Utilizes the original mountings for a hassle-free installation, ensuring a perfect fit.
  • Enhanced Functionality: Upgrades from the standard plastic tank to improve both appearance and performance over time.
  • Kit Includes:
    • Canton Racing Coolant Tank in Wrinkle Black Powdercoating
    • Canton Racing Stant Tank Cap
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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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Sale - Save 25%
$ 10.99

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

$ 8.24 USD
Free Shipping on orders $49 and up

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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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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Moroso - Corporate Logo
T#:29666104
Part#: 63850
In Stock at Vendor
$ 586.00 USD
Free Shipping on orders $49 and up

The coolant expansion tank provides hot coolant with a place to travel, preventing pressure buildup within your cooling system. On many BMWs, this component is constructed from plastic. While cheap to replace and manufacture, a failed cooling tank can cause costly engine damage.

With this issue in mind, Moroso designed a high-quality replacement. Featuring TIG welded, 100% aluminum construction, this tank is sure to outperform it's factory counterpart.

Features:

Key Benefits:

Direct bolt-in replacement for stock, 2 piece plastic tank Fabricated Aluminum for strength, factory tanks fail after repeated high heat situations & age Features billet aluminum mounting tab/bleeder assembly for strength and precision No cutting of factory hoses is required and accepts the factory clip-on hose Included is a Moroso (63324) racing radiator cap that operates in the same pressure range as the factory cap Moroso radiator cap mounts to a billet aluminum neck that will not strip out like plastic threaded necks Can be polished, chromed, or powder coated or left as-is

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