Thermostat housing upgrade in cast aluminum, replacing the factory plastic housing that's a well-known failure point on these engines - the plastic goes brittle from years of hot coolant cycling and eventually cracks, causing a sudden coolant leak and overheating. Ships complete with the thermostat and seal already fitted, so it's a like-for-like swap rather than needing to source the thermostat separately.

Fitment: BMW E39 525i/528i/530i, E46 323/325/328/330 (Ci/i/xi), E53 X5, E60 525i/530i, E83 X3, Z3 and Z4 - M52 and M54 engines (use the vehicle selector to confirm your exact production date range).