MMX Performance BMW Billet Coolant Expansion Cap

The MMR Performance billet coolant expansion caps for BMW have been designed from the ground up in the UK, from a solid piece of billet aluminum. Each cap was designed to directly replace the OE cap, not merely stuck in place. 90mm fitment replaces OE part number 17117639021 while 60mm fitment replaces OE part number 17117639024.

Each MMR cap starts life as a solid billet of 6061 aerospace-grade aluminum. It's meticulously machined from this billet with the latest CNC 5-axis technology, before being polished, then gloss-anodized to stay beautiful year after year.

All MMR coolant caps arrive pre-sealed and pre-installed with an OE spec valve and internal spring. No need to remove the valve assembly from your OE cap. A true plug and play solution.

It has been designed to instantly give your BMW an under-bonnet boost in the aesthetic department, finished in a deep gloss black anodized finish.

Never again will you worry whether you tightened your expansion cap fully, as the cap contains complete OE replacement internals. The carefully considered design gives ample surface grip area for your fingers, making installation and filling your coolant that little bit easier.

It joins an existing range of engine dress-up products for a complete under-bonnet transformation to your engine bay.

NOTE: Caps sold individually. Please check the underside of your factory expansion cap for the OE part number.

Product Features:

• Designed and engineered in the UK
• Crafted from 6061 aerospace-grade aluminum
• Full OE cap replacement
• Sophisticated internal springing and bleed off
• Anodized in MMR signature gloss black
• Joins existing range of MMR billet caps
• Pre-installed factory spec Viton O-Ring