CNC Alloy Thermostat Cap Upgrade for BMW N54, N55 and S55 Engines

Give your turbocharged straight six the finish and reliability it deserves with this precision CNC machined aluminium thermostat housing cap from MMR Performance. Finished in deep black anodise, it replaces the fragile OE plastic top on the oil thermostat assembly to improve durability, resist cracking and sharpen the look of your engine bay.

Stronger, smarter, better looking

• Direct fit replacement for the factory plastic cap on BMW oil thermostat housings used on N54, N55 and S55 engines
• High grade T6061 billet alloy for strength, heat resistance and long term reliability
• Gloss black anodised finish for a premium motorsport look and corrosion protection
• Optional 1/8 NPT sensor port available for adding an oil temp sender, oil pressure sensor or gauge feed
• Helps prevent leaks caused by ageing or cracked plastic tops
• Clean OE style fitment using existing hardware, installs with basic tools

We have installed this cap on customer cars and our own builds. Fit and finish are spot on, and feedback has been consistently positive for both appearance and peace of mind. It is a simple modification that tidies the bay and avoids the common cracked cap issue as mileage climbs.

Ideal for builds that monitor oil data

Choose the version with the integrated 1/8 NPT take off if you plan to run a dash gauge, data logger or standalone oil pressure or oil temperature readout. The threaded port gives you a clean, convenient location for a sender without cutting into lines.

Vehicle fitment

Designed for BMW models using N54, N55 and S55 engines, including:

• 1 Series E82 E88 and F20 F21 135i, 1M, M135i, M135i xDrive 2007 to 2019
• 2 Series F22 F23 M235i, M235i xDrive 2015 to 2019
• 3 Series E90 E91 E92 E93 and F30 F31 335i, 335i xDrive, M3 2007 to 2019
• 4 Series F32 F33 435i, 435i xDrive, M4 2015 to 2019

What is included

• MMR Performance billet aluminium thermostat cap in deep black anodise
• Optional additional cap with integrated 1/8 NPT thread for sensor take off select when ordering

Why enthusiasts choose this cap

• Engine bay dress up that also improves robustness
• Perfect for tuned N54, N55 and S55 cars that see track days or spirited road use
• Pairs well with oil cooler upgrades and instrumentation
• Quality machining and finish from a trusted performance brand

Installation and support

Professional installation available with MJ Modifications in Warwickshire. For a fitting quote email info@mjmodifications.co.uk.

Fitting guide: Download installation instructions

Notes

• Select the 1/8 NPT option if you intend to add an oil pressure or oil temperature sender
• Extended exposure to very high temperatures can alter the appearance of anodised finishes

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