We have noted more M54 engine failures due to overheating than on any of BMW's previous engines. Based on design changes to the M54, we infer that the problem is peak operating temperature that is too high; according to BMW's technical literature, the factory thermostat is computer controlled to operate from 80 ° C to 103 ° C. BMW also reports that a mechanical failsafe does not open until the coolant temperature reaches 110 ° C. That's a 230 ° F temperature band, which may also contribute to engine failures. As too many can attest, temperature related failures often end with engine replacement. M54 engines have aluminum blocks which are subject to having the head bolts strip the block of its threads. Our Competition Thermostat Housing, machined from billet T-6061 aluminum and anodized for protection, is designed to return the selection of normal engine operating temperature to the owner/builder and improve engine longevity by replacing the failure prone plastic electronically-controlled thermostat with a mechanical unit. (Replaces BMW part no. 11 53 7 509 227) Kit includes aluminum housing, seal, o-ring, screws (4), washers (4) and 92 degree mechanical thermostat.