BMW 3 Series E30

since 1983-1994 release

Repair and operation of the car

+ 1. Maintenance instruction
+ 2. Maintenance
+ 3. Engine
- 4. Cooling system
   4.2. Specifications
   4.3. Antifreeze
   4.4. Thermostat
   4.5. Radiator
   4.6. Fans and coupling of the drive
   4.7. Pump of cooling liquid
   4.8. Sensor of temperature of cooling liquid
+ 5. Heating and ventilation
+ 6. Fuel system
+ 7. Exhaust system
+ 8. Transmissions
+ 9. Coupling
+ 10. Brake system
+ 11. Running gear
+ 12. Body
+ 13. Electric equipment
+ 14. Useful tips


4.4. Thermostat


Collars of hoses on the case of the thermostat of the 4-cylinder engine

Thermostat branch pipe on the 6-cylinder engine

The thermostat case, thermostat and sealing ring are removed.

The correct arrangement of the thermostat on a final branch pipe of the cooling system (6-cylinder engine)

The tag in the form of an arrow has to be turned up. To tighten bolts of fastening with m 9±1 N.'s moment.


If the engine long gets warm, then the thermostat should be replaced. Previously check the liquid level, condition of a belt of the drive of the pump and serviceability of the sensor and the index of temperature.

The thermostat also should be replaced if on the heated-up engine the top hose of a radiator cold.


1. Disconnect the battery from weight and merge cooling liquid.
M10 engine
2. Remove the fan.
3. Release collars of the lower hose of a radiator and get the thermostat.
4. Installation is carried out upside-down.
M20 engine

5. Release a collar and disconnect hoses from thermostat branch pipes.
A. Collar
B. Liquid temperature sensor
6. If the branch pipe of the thermostat is damaged by corrosion, then replace the thermostat.
7. Turn off bolts and remove the thermostat case.
8. Remove the thermostat.

9. Remove the remains of consolidation or remove laying of the case of the thermostat.
10. Replace laying, install the new thermostat and attach a hose.
M40 engine
11. Remove the fan and the top cover of a gear belt.
12. Release a collar and disconnect the lower hose from a knee in a forward part of a head of cylinders.
12. Turn off bolts and remove a branch pipe.
13. Get the thermostat.
14. Install the new thermostat and replace laying. Assembly is carried out upside-down.