Replace the factory plastic coolant reservoir cap with this precision-machined billet aluminum upgrade. Designed for long-term durability and a clean OEM+ appearance, this cap adds both strength and style to your engine bay while retaining full factory functionality.

This upgrade eliminates the weak plastic construction found on stock caps and delivers a refined, performance-inspired finish that complements other engine bay enhancements.

Key Features

• Machined from solid 6061 billet aluminum for superior strength
• Anodized finish for corrosion resistance and long-lasting appearance
• Precision CNC machining ensures accurate fitment
• Direct replacement for the factory coolant reservoir cap
• Retains original pressure relief functionality

Installation Notes

• Requires transferring the factory pressure relief valve from the original cap
• Simple hand-tool installation
• Not compatible with select high-performance and specialty models (see fitment notes)

Specifications

• Material: 6061 billet aluminum
• Finish: Anodized
• Placement: Coolant expansion tank / engine bay
• Replacement Reference: 17117639020, 17117521071

Important Fitment Exclusions

• Does not fit E9X M3 models
• Does not fit F8X M2 / M3 / M4
• Does not fit F10 530i, 550i, or M5

Vehicle Fitment

• BMW 1 Series: E81, E82, E87, E88, F20, F21
• BMW 2 Series: F22, F23
• BMW 3 Series: E90, E91, E92, E93, F30, F31, F34
• BMW 4 Series: F32, F33, F36
• BMW 5 Series: F07, F10, F11, G31, G38
• BMW 6 Series: F06, F12, F13
• BMW 7 Series: F01, F02
• BMW X Series: X1 (E84), X3 (F25), X4 (F26), X5 (E70, F15), X6 (E71, F16)
• BMW Z Series: Z4 (E89)

What’s Included

• 1x Billet Aluminum Coolant Reservoir Cap

This billet coolant reservoir cap is a simple yet effective upgrade for BMW owners looking to improve reliability, aesthetics, and engine bay presentation without compromising factory functionality.