BMW N54 N53 N52 N20 N55 thermostat to head coolant hose fitting, 11537541992 11537544638

This CNC-machined billet 6061 aluminium fitting replaces the fragile plastic thermostat-to-head connector on BMW N54, N53, N52, N20 and N55 engines. It’s a fast-road or track-day upgrade that stops coolant leaks before they start - no more brittle plastic snapping under heat or boost.

Fits exactly like OEM: direct replacement for part numbers 11537541992 and 11537544638. Includes correct O-ring spec - thinner for N55, standard for others.

• No modifications - bolts straight in with stock hoses and clamps
• Track-proven - handles higher temps and sustained load better than plastic
• DIY-friendly - typical install takes under 20 minutes with basic tools