N55 coolant pipe O-ring gasket 11537584829 for BMW 135i, 335i, X3, X5

Replace the weak-point O-ring on your N55’s upper coolant pipe - the most common source of slow, hard-to-diagnose coolant loss. This is the exact gasket (part number 11537584829) used at the water pipe junction on all N55 engines.

• Fits every N55: 135i, M135i, 335i, 435i, 535i, 640i, 740i, X1, X3, X4, X5, X6
• Heat- and pressure-rated rubber compound - no aftermarket guesswork
• Essential during thermostat, water pump or pipe upgrades - especially for fast road or track day builds
• Not a ‘genuine replacement’ - it’s the part you need, stocked and ready