Moroso 63851 Aluminum Coolant Expansion Tank for 06-16 BMW 1/3 Series/Z4/X1

Vehicle Fitment

• 2008-2013 BMW 1 Series E82/E88 (128i/135i, 3.0L I6, RWD, non-M)
• 2006-2013 BMW 3 Series E90/E91/E92/E93 (323i/325i/328i/330i/335i/335is, 2.5L/3.0L I6, RWD/xDrive, non-M)
• 2009-2016 BMW Z4 E89 (sDrive23i/sDrive28i/sDrive30i/sDrive35i/sDrive35is, I6 engines, RWD)
• 2009-2016 BMW X1 E84 (sDrive28i/xDrive28i/xDrive35i, I4/I6, RWD/AWD, non-M)

Fitment Notes

• Direct bolt-in replacement for the factory plastic coolant expansion tank on E82/E88, E90/E91/E92/E93, E89 and E84 non-M models.
• Designed specifically for non-M BMW applications; does not fit M3 or other M-variant cooling layouts.
• Reuses factory hoses and clip-on connections--no cutting or splicing of coolant hoses required.
• Includes a Moroso high-performance radiator cap operating in the same pressure range as the OEM cap.

Features

• Fabricated 100% aluminum tank replaces failure-prone OEM plastic reservoir.
• TIG-welded construction for superior strength and leak resistance under high temperature and pressure.
• Billet aluminum mounting tab and bleeder assembly provide precise fit and long-term durability.
• Direct-fit design uses factory mounting points and hose routing on supported BMW platforms.
• Improved resistance to cracking and deformation compared to molded plastic tanks.
• Engineered to handle repeated heat cycles in performance and track environments.
• Helps maintain stable cooling system pressure to protect engine and cooling components.
• Clean aluminum appearance enhances the look of the engine bay on E9X, E8X, E89 and E84 models.

Specifications

• Part Number: 63851
• Application: Coolant expansion tank (BMW 1 Series, 3 Series, Z4, X1 non-M)
• Material: Fabricated aluminum (tank) with billet aluminum mounting/bleeder components
• Finish: Natural aluminum
• Cap Included: Moroso 63324 high-performance radiator cap (OEM-equivalent pressure range)
• Compatibility: Direct bolt-in to OEM mounting points and hose connections on listed chassis

Included Components

• 1x Moroso 63851 aluminum coolant expansion tank
• 1x Moroso 63324 radiator cap
• 1x Mounting hardware kit (as supplied by Moroso)
• Installation instructions

Product Description

The Moroso 63851 aluminum coolant expansion tank is a direct-fit upgrade for select BMW 1 Series, 3 Series, Z4 and X1 non-M models, replacing the stock plastic reservoir with a far more durable fabricated aluminum unit. The factory plastic tanks are known to fatigue and crack over time, especially on performance-oriented or high-mileage cars, which can lead to coolant loss and potential engine damage.

Constructed from TIG-welded aluminum with a billet mounting and bleeder assembly, the 63851 tank is built to withstand repeated heat cycles and high under-hood temperatures. It reuses the factory hoses and clip-on connections for a clean, bolt-in installation, and includes a Moroso high-performance radiator cap matched to OEM pressure range. For E82/E88, E90-E93, E89 and E84 owners looking to improve reliability and engine bay appearance, this Moroso expansion tank provides a robust, track-capable solution tailored specifically to these BMW platforms.