Billet Aluminum Coolant Port Fitting Upgrade for BMW N52 N54 N55 N20

This Billet Aluminum Coolant Port Fitting — often called the "Mickey Mouse flange" among BMW enthusiasts for its distinctive twin-eared shape — is a direct-fit upgrade for BMW N52, N54, N55, and N20 engines, replacing the OEM plastic coolant hose fitting that is a well-known failure point in BMW cooling systems. Despite years of factory revisions, the plastic fittings and adapters still crack under repeated heat-cycle stress. On the N54 engine specifically, the plastic cylinder head outlet adapter that connects the cylinder head to the thermostat hose commonly snaps off at the barb end, causing a sudden and severe coolant leak.

Why Upgrade to a Billet Aluminum Coolant Port Fitting (Mickey Mouse Flange)

• Perfect Replacement — The original plastic hose fitting is a well-known weak point in the BMW cooling system, as it often cracks and leaks. This upgraded aluminum coolant hose fitting replaces the stock fitting with one that will never wear out, crack, or leak.
• Aircraft-Grade 6061 Billet Aluminum — CNC-machined from solid 6061 aluminum instead of plastic, for a durable, wear-resistant coolant port fitting built to last the life of the car.
• Smooth Internal Flow — This coolant fitting has no sharp internal corners, so coolant flow is never interrupted or restricted.
• Maximum Coolant Flow — The larger internal diameter versus the original plastic part improves coolant flow and overall cooling performance.
• Easy Direct-Fit Installation — Bolts straight onto the factory location with no cutting or modification required.

Specification

• Type: Water/coolant hose fitting, also known as the "Mickey Mouse flange"
• Housing material: Billet (CNC-machined) 6061 aluminum
• Surface finish: Anodized
• Replaces part numbers: 11537649409, 11537605152, 11537603514, 11537598234, 11537592095, 11537591889, 11537585023, 11537584549, 11537581063, 11537580969, 11537578727, 11537566329, 11537560363, 11537552339, 11537550062, 11537545890, 11537541992, 11537603514

Package Includes

• 1x Solid billet aluminum coolant port flange fitting
• 1x Heavy-duty O-ring

Note: N55 engines require a slightly thinner O-ring. If you need a replacement O-ring in the future, refer to part number 11537545278 (29x2.9mm).

BMW Engine & Model Fitment

Fits BMW N20 / N26 / N51 / N52 / N54 / N55 engines, including:

• BMW 1 Series E81/E82/E87/E88 125i 128i 130i 135i 135is 1M 2008-2013
• BMW 1 Series F20/F21 125i 2012-2015
• BMW 1 Series F20/F21 M135i 2012-2016
• BMW 2 Series F22/F23 220i 228i M235i 2014-2016
• BMW 3 Series E90/E91/E92/E93 323i 325i 328i 330i 335i 2005-2012
• BMW 3 Series F30/F31/F34 320i 328i 335i 2012-2015
• BMW 4 Series F32/F33/F36 420i 428i 435i 2013-2016
• BMW 5 Series E60/E61 523i 525i 528i 530i 535i 2005-2010
• BMW 5 Series F10/F11 520i 523i 528i 530i 535i 2010-2016
• BMW X1 Series E84 16i 20i 25i 28i 35i 2009-2015
• BMW X3 Series E83 25i 30i 2006-2010
• BMW X3 Series F25 20i 28i 35i 2011-2017
• BMW X4 Series F26 20i 28i 35i M40i 2014-2018
• BMW X5 Series E70 30i 35i 2007-2013
• BMW X5 Series F15 35i 2013-2018
• BMW X6 Series E71 35i 2008-2014
• BMW X6 Series F16 35i 2015-2019
• BMW Z4 Series E85/E86 25i 30i 2006-2008
• BMW Z4 Series E89 18i 20i 23i 28i 30i 35i 2009-2016

Installation Tips

• Remove the two 10mm bolts.
• Remove the old fitting from the engine block. The O-ring must also be removed, as it may be stuck.
• Clean the outlet on the engine block. Remove any remaining coolant hose residue.
• Install the new fitting. Lubricate the sealing ring before installation. Tighten the two 10mm bolts.
• Slide the coolant hose onto the outlet port. Tighten the clamp.

Disclaimer: E9x Performance Parts products are not sponsored by, endorsed by, or affiliated with the brands they are designed to fit, including Porsche, Subaru, Jaguar, BMW, Isuzu, Chrysler, Dodge, Jeep, Buick, Cadillac, Chevrolet, GMC, Volvo, Land Rover, Oldsmobile, Pontiac, Ford, Lincoln, Mercury, Acura, KIA, Nissan, Infiniti, International Harvester, Mitsubishi, Audi, Lexus, Toyota, Mazda, Volkswagen, Suzuki, Saab, Honda, Alfa Romeo, Saleen, Mercedes-Benz, Nash, Hummer, Freightliner, Datsun, Saturn, Turner, Geo, Lada, Fiat, Daihatsu, Opel, Vauxhall, Sabra, Tesla, Ram, Rover, Skoda, Healey, Mini, Smart, Scion, Renault, Seat, Peugeot, Merkur, Astra, Tucker, VW, Routan, Tiguan, Touareg, Jetta, GTI, Passat, Golf, Bosch, Denso, Holden, Chery, Holden Special Vehicles, Hyundai, Trabant, Citroën, and others.