BMW 11537511580 Behr Thermot-Tronik Thermostat

To replace the thermostat on E30 models with S14, M20, or M42 engines, start by draining the coolant and loosening the hose clamps or bolts on the thermostat housing. Remove the thermostat and install the new one, ensuring the support bar faces out for M20 and M42 models. Replace the O-ring and gasket where necessary and torque the bolts. For E36 models, disconnect the battery, remove the radiator trim cover, cooling fan, and hoses. Loosen the housing bolts and replace the entire unit if the thermostat is installed into the housing. Check the housing for cracks, replace the seal, and install the new thermostat with the air bleed hole up. Coat the bolts with anti-seizing compound, tighten them, and reassemble the remaining parts. Finally, bleed the cooling system and enter the radio security code.