This aluminum coolant fitting is designed and manufactured to precise tolerances to fit the OEM application but with notable improvements in function.  This product is made from high strength aerospace aluminum, Grade 6061 T6511.  Also, this product was designed to maximize the resistance to breakage, so that it will not fail as the OEM fitting does.  In addition to this, the coolant flow path through the center of the fitting is optimized to maximize coolant flow.  There are no sharp corners on this fitting so that the coolant will not be disrupted as it passes through.  Along this same line, the surface area of the coolant flow path is 23% larger than the OEM pieces which further optimizes coolant flow, improving cooling performance.

This product is an OEM replacement for the plastic fitting on BMW PN 11537541992 and 11537544638.  It fits the N54, N53, N52 and N51 3.0-litre motors.  This BMW PN consists of a 25mm (1.0") hose and a plastic fitting.  This hose runs from the coolant thermostat housing to the front of the head.  The plastic fitting on this hose is a known weak spot in the coolant system as it commonly cracks and leaks.  The ideal solution to the problem is to replace the fitting with one that will never wear-out, crack or leak.  This fitting is a direct replacement for the stock plastic fitting with no modification to any part of the system necessary.  Simply remove the end of the hose from the plastic fitting and then the fitting from the head  (hose does not need to be removed from the thermostat housing to do this).  Then install the replacement aluminum fitting to the head and slide the hose and hose clamp over the fitting.  Fitting is machined from billet aluminum 6061 T6511 (not cast, not forged).

The shipment includes the aluminum fitting, new o-ring already installed on the fitting and a stainless steel hose clamp. Be sure to add a thin film of grease to the oring before install.  This listing does NOT include the hose.

Fits 3.0L twin-turbo N54 (3.0-litre twin turbo) motors 335i, 335xi, 135i and the N53 (3.0-litre non-turbo) 2006 - 2010 325i, 330i, 525i, 525xi, 528i, 528xi, 530i, 530xi and the N20 (2.0-litre turbo) Z4 2013-, and the N52 X3.  This fitting also fits the next generation N55 motors in all chassis.

If you track or race your 335i then this is a highly advisable upgrade as this aluminum coolant fitting will not crack under high-temperature track conditions.