This Mahle-Behr thermostat (11537511580 / ES#205288), rated to open at 88C, is the OE-specification cooling thermostat for BMW's early-1990s to mid-1990s small-displacement engines. It regulates coolant flow to bring the engine up to operating temperature quickly and then hold it in the correct range, and is a routine wear item that should be replaced if the engine is running cold, overheating, or the housing is leaking.

Fitment: BMW E30 318i/318is and E36 318i/318ic/318is/318ti (M42 1.8L), E34 525i and E36 325i/325ic/325is (M50 2.5L), E36 M3 (S50 3.0L / S52 3.2L), and Z3 M Coupe/M Roadster (S52 3.2L) — not the later N52-powered E82/E60/E83/E70/E85 models on the original listing.