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 - 603-755, 603755, 17137640515, 17137590626. 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 2011 - 2013 BMW 135i, 2013 BMW 135is, 2011 - 2013 BMW 335i, 2009 - 2013 BMW 335i xDrive, 2013 - 2016 BMW M135i, 2012 - 2015 BMW X1. Please check the description or enter Year / Make / Model on Amazon's Fitment Filter system to confirm your compatibility. 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 Number: 603-755, 603755, 17137640515, 17137590626.
Color: Black
Cap Included: Yes
Cap Maximum Pressure Rating: 20.3 PSI
Cap Type: Spring Loaded Twist
Capacity: 1.6 L Level Sensor Included: Yes Mounting Hole Quantity: 2 Material: Plastic

Compatible with Select BMW Models -

2011 - 2013 BMW 135i

2013 BMW 135is

2011 - 2013 BMW 335i

2009 - 2013 BMW 335i xDrive

2013 - 2016 BMW M135i

2012 - 2015 BMW X1

Package Includes -
1 x Coolant Radiator Reservoir Tank with Sensor & Cap