1. Locate the coolant expansion tank. It's usually located on the driver's side of the engine bay, near the front. It's a white plastic tank with a black cap.
2. Follow the upper radiator hose. It's the large hose that connects the radiator to the engine.
3. The thermostat is located at the end of the upper radiator hose, where it connects to the engine. It's a round, metal housing with one or two sensors attached to it.
4. The thermostat is held in place by two bolts. Remove these bolts to remove the thermostat.
- Note: On some models, you may need to take the thermostat housing off the intake manifold to access the thermostat.
That is the location of the thermostat on the BMW Z3 1.9L.
