ECS Heavy Duty Aluminum Expansion Tank - Gen 2 MINI R55, R56, R57, R58, R59, R60, R61

Product Details

- Click HERE for Installation Instructions -

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.

** Cap Design yellow warning on it now like OEM **

Features & Benefits:

• Manufactured from 5052 and 6061 aluminum with full TIG welds, providing high structural integrity that easily withstands elevated engine temperatures and severe cooling system pressure.
• Pressure tested to 31 psi to guarantee zero fluid leakage and long-term seam reliability.
• Features a clear external sight glass set at the low-level mark for rapid visual checks, alongside an internal fill tab to indicate the exact full-capacity line during service.
• Engineered to utilize stock mounting locations—sliding directly into the lower rubber mount and snapping over the factory retaining tabs to use original hardware.
• Inlet, outlet, and cap connections are CNC-machined to exacting tolerances for a reliable, leak-free union with factory cooling lines.
• Wrinkle black powder coat protects raw aluminum from surface oxidation while maintaining a subtle, factory-like aesthetic in the engine bay.
• Directly replaces original plastic expansion tank part numbers 17137539267 and 17137823626 across all Gen 2 MINI R55-R61 platforms.

Kit Contents:

• Heavy Duty Aluminum Coolant Expansion Tank
• Expansion Tank Cap

Installation:

Looking for installation instructions? ECS Tuning has assembled a start-to-finish installation guide, including detailed instructions on removing your factory components. - CLICK HERE for Installation Instructions -

Prop 65 Warning

Product Q&A

Lifetime Replacement

Fits These Cars