FL-152403

• Maintains factory 15 psi system pressure, raising coolant boiling point to ≈250 °F and preventing coolant loss under steep-grade or high-load conditions.
• Plunger-style relief valve releases excess pressure in a controlled manner and seals instantly as the system cools, preventing air ingress that can trigger low-coolant warnings.
• High-impact polymer body resists cracking from vibration and DEF vapor; EPDM gasket withstands repeated thermal cycles without hardening.
• Direct screw-on replacement—no tools required. Verify that the bottle’s neck and threads are free of debris before installation to ensure an airtight seal.

Replacement surge-tank cap for 2018-up Freightliner Cascadia tractors. Built to Daimler’s OE spec, the cap’s spring-loaded plunger holds 15 psi, safeguarding the cooling system and avoiding premature hose or tank failures. The 2.25-in diameter and 0.75-in depth match the factory bottle; installation restores correct pressure control and protects the DD13/DD15 cooling loop.