Withdrawal
The thermostat is firmly built into the housing and cannot be removed from there. If there is a defect, it must be replaced together with the housing.
1. Drain the coolant, refer to Section Coolant replacement.
Models 320i, 323i, 328i
2. Models with air conditioning: Disconnect the viscous fan, refer to Section Removing and installing a viscous fan.
3. Turn away bolts of fastening and remove an eye in front on the engine.
Models 320d
4. Remove the AGR radiator from the end side of the engine.
5. Disconnect the coolant line under the thermostat housing at the cylinder head and holder.
6. Disconnect the coolant hoses from the thermostat housing -1- on the front side of the cylinder block. To do this, pull the wire lock up with a screwdriver, refer to Section Connecting and disconnecting the quick coupling.
7. Disconnect the connector from the thermostat housing.
8. Turn away the case of the thermostat and remove together with a sealing lining -2-.
The thermostat cannot be checked in the usual way by immersion in a container of hot water, since its opening temperature lies above the boiling point of 105°C.
Installation
9. Clean the sealing surfaces on the body and cover and wipe with a cloth dampened with alcohol.
10. Evenly fasten the thermostat housing with a new sealing gasket to a torque of 10 Nm.
11. If deformed, replace the O-rings on the quick couplers. Push in the wire retainers. Put on the hoses, while the coupling must be clearly fixed.
12. Dock the connector at the thermostat housing.
13. Models 320i, 323i, 328i: Fasten the engine lug with a torque of 20 Nm.
14. Models 320i, 323i, 328i with A/C: Install a viscous fan, refer to Section Removing and installing a viscous fan.
15. Models 320d: Secure the coolant line under the thermostat housing with its gasket. Fix the pipeline on the holder. Install the AGR radiator, refer to Section Removal and installation of the inlet pipeline.
16. Fill the system with liquid and remove air, refer to Section Coolant replacement.
17. Start and warm up the engine. Check if the radiator has warmed up and if the thermostat housing is tight. If there are leaks, tighten the mounting bolts.