A) Friction coupling Remove and install fan-see 11 52 000. Remove drive shell. Remove clutch drum.  11 52 000
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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. ¹ See specifications
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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. |  |
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