A) Friction coupling
Remove and install fan-see 11 52 000.
Remove drive shell.
Remove clutch drum.


Siehe auch 11 52 000
52020001 - click to zoom
 
Note when fitting: Always replace entire fan coupling¹.
The working element (A) is matched exactly with drive shell (B).
C must be 5 mm (0.197").
Coution! If a new fan coupling is not available for a repair,
the fan coupling can be blocked for a limited time with two M 6 x 30 mm
screws. The fan then turns continuously.
The screws should be opposite each other to avoid serious unbalance.




Siehe auch ¹ See specifications
52020002 - click to zoom
 
B) Viscous coupling
A viscous fan coupling depends on the temperature.
The cut-off speed² of the fan is reached when the water pump
turns faster than the fan.
The fan coupling must be replaced in the following cases.
a) Hub has seized-with the engine off the fan cannot be turned,
or is difficult to turn.
b) Fan coupling loses oil due to axial or radial play-the fan will not
attain cut-off speed².
c) Dynamic check of cut-off speed with a stroboscope lamp as follows.
Run engine to operating temperature.
Connect stroboscope lamp. Make chalk mark on fan hub and point
stroboscope lamp at it. Use speed booster 12 1 070 to slowly increase
speed until chalk mark stands still i.e. the chalk mark will
move counter-clockwise as seen in the driving direction until the
cut-off speed is reached².

²A viscous coupling must be replaced if the viscous fan`s
cut-off speed is less than 2000 rpm.

52020003 - click to zoom
 
Remove fan-see 11 52 000.
Loosen fan mounting screws and remove fan coupling.


Siehe auch 11 52 000
52020004 - click to zoom