Electrical Cooling System Switches — Removal and Installation (Mercedes-Benz C-Class W201)

Contents: Coolant level sensor ↡ Coolant Temperature Gauge Sensor ↡

Note: The steps for removing and installing the cooling system sensors included in the fuel and ignition systems are described in the relevant sections Chapters 4.

Coolant level sensor

Removal

1. The sensor is located on the side of the expansion tank (see fig. 6.1). Check that the engine has cooled down, then follow the description in Chapter 1, partially drain the cooling system to free the expansion tank.

Fig. 6.1. Location of the coolant level sensor (shown by arrow)

2. Check that the ignition is off, then disconnect the plug from the fluid level sensor connector.

3. Remove the retaining ring and take the sensor out of the expansion tank. Remove the sealing ring if it is loose.

4. Connect a probe or a multimeter set to measure resistance between the sensor contacts. When holding the float at the top point, the resistance should be high (the circuit is open). If the float is lowered so that it hangs at the bottom of its stroke, the circuit should be closed and the resistance should be zero.

Installation

5. Installation is carried out in reverse order. Please note the following features:

a) Install a new sealing ring onto the sensor housing.
b) When finished, top up the system with coolant as described in Chapter 1.

Coolant Temperature Gauge Sensor

Removal

6. The sensor that controls the coolant temperature gauge is screwed into the top of the cylinder head on the left side of the engine. Do not confuse it with the fuel/ignition coolant temperature sensor that is mounted nearby.

7. Check that the engine has cooled down, then follow the description in Chapter 1, partially drain the cooling system to free the expansion tank.

8. Make sure the ignition is off, then disconnect the plug from the sensor connector.

9. Unscrew the sensor from the cylinder head and remove the sealing ring.