What Does a Coolant Reservoir Do? - A coolant reservoir is a small plastic tank that is connected to the radiator of a car’s cooling system. Its primary function is to provide a space for excess coolant to expand and contract as the engine heats up and cools down. Keep the engine operating at a normal temperature. Part Numbers - 603-351, 603351, 17137542986, 17137519219, 17137521189, 17137555234. This radiator surge tank matches the fit and function of the original part. This is NOT a genuine part, it's an aftermarket replacement part. Compatible with Select BMW Models - This radiator overflow tank is compatible with 2004-2010 BMW 525i, 2006-2007 BMW 525xi, 2008-2010 BMW 528i, 2009-2010 BMW 528i xDrive, 2008 BMW 528xi, 2004-2010 BMW 530i, 2006-2007 BMW 530xi, 2008-2010 BMW 535i, 2009-2010 BMW 535i xDrive, 2008 BMW 535xi, 2004-2006 BMW 545i, 2006-2010 BMW 550i, 2010 BMW 550i GT, 2004-2005 BMW 645Ci, 2006-2011 BMW 650Ci, 2006-2010 BMW 650i. Please check your compatibility before purchasing this reservoir tank. Replacement Instruction - Turn off and cool down the car, disconnect the drain line, remove the retaining bolts and swap in the new reservoir tank. Professional installation is highly recommended. Durable and Long Lasting - This Coolant Recovery Tank is manufactured from quality materials, durable and long lasting. It is thoroughly tested to ensure optimum fit and performance on specific vehicle applications. Features -
Premium material.
Direct replacement.
Keeps the engine operating at a normal temperature.

Specifications-
Part Numbers: 603-351, 603351, 17137542986, 17137519219, 17137521189, 17137555234.
Color: Black
Sensor Included: Yes
Cap Included: Yes
Cap Maximum Pressure rating: 22 PSI
Cap Type: Spring Loaded Twist
Material: Quality Plastic
Pressurized: Yes

Compatible with select BMW Models -

2004 - 2010 BMW 525i

2006 - 2007 BMW 525xi

2008 - 2010 BMW 528i

2009 - 2010 BMW 528i xDrive

2008 BMW 528xi

2004 - 2010 BMW 530i

2006 - 2007 BMW 530xi

2008 - 2010 BMW 535i

2009 - 2010 BMW 535i xDrive

2008 BMW 535xi

2004 - 2006 BMW 545i

2006 - 2010 BMW 550i

2010 BMW 550i GT

2004 - 2005 BMW 645Ci

2006 - 2011 BMW 650Ci

2006 - 2010 BMW 650i

Package Included -
1 x Coolant Radiator Reservoir Tank
1 x Cap