Test conditions:

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2005 Porsche 911, 2004 Porsche 911, 2003 Porsche 911, 2002 Porsche 911, and 2001 Porsche 911. However, it is still accessible from the selected car via links, so may be relevant.

Test only with viscous clutch at room temperature.
Test duration: max. 45 seconds (determine measured value after 20 seconds).
Repeat measurement after viscous clutch has cooled down for one hour.

Connect Porsche System Tester 2 and select "Actual values" menu (ABS speed).
Drive front wheels of the vehicle onto the roller brake tester.
Switch the engine off, set the hand brake and shift the transmission to neutral.
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.
Drive front wheels via the rollers of the brake tester (max. 8 km/h or 5 mph) and measure traction of the front wheels after 20 seconds.
NOTE: When measuring wheels individually, the values of the two front wheels must be added.
The viscous clutch functions properly if the traction of the front wheels lies within the limit curves in Figure . At the same time, the ground speed of the front axle (can be read off on the Porsche System Tester 2) must be taken into account.

For example:

At 5 km/h (3 mph) ground speed, the traction of an intact viscous clutch must lie between approx. 600 N and 1450 N (refer to Figure ).