Rein EPT0018 Engine Coolant Reservoir

OE Quality Expansion Tank for BMW Cooling Systems

Restore proper coolant expansion and recovery with the Rein EPT0018 engine coolant reservoir. This OE-quality expansion tank is built for BMW applications and is designed to match the original fit, material standards, and cooling-system function expected from the factory part.

Compatible With BMW X3, BMW X5, BMW 325Ci, BMW 330Ci, BMW 320i, BMW 325i, BMW 325xi, BMW 330i, BMW 330xi, BMW 323Ci, BMW 323i, BMW 328Ci, and BMW 328i applications across the listed model years.

• Produced from virgin plastic to meet or exceed OE material specifications
• Resists cracking and wear caused by repeated heat cycles
• Direct-fit design supports straightforward installation
• Built to strict engineering standards for material quality and tolerances
• Helps maintain stable coolant level management in the cooling system

Built for OE-Style Fit and Durability

The Rein EPT0018 expansion tank is engineered as a direct replacement for the original coolant reservoir used on select BMW models. Virgin plastic construction helps reduce the risk of premature cracking, while the OE-style design supports proper fitment and reliable long-term service in demanding engine bay temperatures. This part cross-references BMW OE numbers 17111436413 and 17117573781 for the same application.

Use this expansion tank when servicing a leaking, brittle, or heat-damaged reservoir on BMW X3, BMW X5, or 3 Series models. The Rein EPT0018 is intended to restore the cooling system’s ability to store and return coolant as temperatures change.

Common Problems This Part Can Address

• Coolant loss from a cracked or aging reservoir
• Visible plastic damage from repeated heat cycling
• Low coolant warnings caused by reservoir leakage
• Cooling-system service needs on BMW X3, X5, and 3 Series vehicles
• Poor sealing or fit issues from worn original equipment

Installation Notes

Before installation, inspect the reservoir cap, hoses, clamps, and nearby cooling-system components for wear or contamination. Drain coolant as needed, transfer any required sensors or fittings from the original unit if applicable, and verify all connections are clean and properly seated before refilling and bleeding the system according to BMW service procedures.

Quality Assurance

Rein designs OE-quality expansion tanks to meet strict material and dimensional standards for BMW cooling-system service. The EPT0018 is manufactured from virgin plastic with no regrind to support durability and long service life in heat-cycle environments.