EVO-X 4B11 Coolant Expansion Header Tank

4B11 EVO-X Coolant Expansion Tank

Our 4B11 EVO-X Coolant Expansion Tank is a direct bolt-in replacement for the OEM thermostat housing, engineered for performance, reliability, and clean engine-bay aesthetics.

This tank includes an additional bleed point and a billet 3-port NPT plate, simplifying plumbing and sensor integration when upgrading to an aftermarket ECU setup. It also accommodates OEM sensors for those retaining factory electronics.

For builds running an aftermarket electric water pump, the tank can be customized with AN-fitting welds for seamless integration. We also offer a CNC laser-cut block-off plate with a welded AN fitting that bolts directly to the water-pump housing — available as an option.
When running an electric water pump, this setup eliminates the OEM hard line that runs beneath the hot turbo manifold, allowing you to route lines directly from the water pump housing in the opposite direction — away from excessive heat exposure for improved reliability and efficiency.

If you’re retaining the OEM mechanical water pump, the system can be configured with an inline thermostat housing back to the radiator to maintain optimal cold-start engine temperatures.

Features

• CNC laser-cut flanges
• Precision TIG-welded in-house
• Direct bolt-in replacement
• Billet high-pressure radiator cap
• Optional AN-fitted block-off plate for electric water pump conversion
• Heat-optimized routing when using an electric water pump