BMW Brass Radiator Coolant Expansion Tank Bleeder Vent Screw 11 53 7 793 373

Description

The Brass Coolant Expansion Tank & Radiator Bleeder Vent Screw (Part # 11537793373) is a high-durability upgrade over the factory plastic bleeder screws installed on BMW cooling systems. Located on the expansion tank housing or upper radiator hose fitting, its primary function is to allow trapped air to escape the cooling system during coolant flushes and refilling.

The original plastic OEM bleeder screws are notorious for becoming brittle over time from heat cycling, easily snapping in half, or stripping out during basic maintenance. This solid brass replacement eliminates the risk of thread shear, head stripping, and sudden heat-induced snapping.

Technical Specifications & Cross-References

Vehicle Compatibility

Compatible with almost all modern and classic BMW models utilizing plastic coolant expansion tanks or upper radiator hose bleeder ports:

• BMW 1 Series: E81, E82, E87, E88 (128i, 135i) (2008–2013)

• BMW 3 Series: E30, E36, E46, E90, E91, E92, E93 (318i, 323i, 325i, 328i, 330i, 335i, M3) (1984–2013)

• BMW 5 Series: E28, E34, E39, E60, E61 (525i, 528i, 530i, 535i, 540i, 550i, M5) (1985–2010)

• BMW 7 Series: E32, E38, E65, E66 (740i, 745i, 750i, 760i) (1988–2008)

• BMW X Series: X3 (E83), X5 (E53, E70), X6 (E71) (2000–2013)

• BMW Z Series: Z3 (E36/7), Z4 (E85, E86, E89) (1996–2016)

Why Upgrade to Brass?

• Prevents Snapping & Leakage: Stock plastic screws shrink and embrittle over time, causing the threaded shank to break off inside the expansion tank housing when tightened.

• Reusable & Corrosion-Resistant: Solid brass construction allows for repeated opening and closing without stripping the screw head or threads.

• Direct Drop-In Replacement: Matches factory thread size and length exactly—no modification required.

Critical Tightening Warning

Do not over-torque the brass bleeder screw. While the brass screw itself will not break, over-tightening can strip the plastic female threads inside your plastic expansion tank or coolant hose neck. Hand-tighten snug until the rubber O-ring seals flat against the surface.