Viscous Coupling: Testing and Inspection

Test Conditions

- Test only with viscous clutch at room temperature.

- Test speed of front wheels between 3 km/h and 5 km/h (wheels driven by rollers of roller brake tester). Test duration 3 minutes; record the traction every 30 seconds.

- Repeat measurement after viscous clutch has cooled down for one hour.


Checking Function of Installed Viscous Clutch

1. Connect Porsche System Tester 2 and select -Actual values- menu (PSM speed).

2. Drive front wheels of the vehicle onto the roller brake tester.

3. Switch the engine off, set the hand brake and shift the transmission to neutral.

4. When the brake-tester rollers have started, switch the ignition on and press the Continue key of the Porsche System Tester 2. The Tester then returns to the point at which diagnosis was interrupted.

5. Drive front wheels by means of the brake tester rollers at a speed of 3 km/h, 4 km/h or 5 km/h.

6. Measure traction 6 times in three minutes. Measure the first traction value after 30 seconds operating time, then carry out five more measurements every 30 seconds.

7. The viscous clutch functions properly if the traction of the front wheels lies within the limit curves in the diagram, depending on the drive speed of the roller brake tester rollers.




Diagram for roller brake tester - speed 5 km/h:




Diagram for roller brake tester - speed 4 km/h:




Diagram for roller brake tester - speed 3 km/h: