300TD (123.193) L5-3.0L DSL Turbo (617.952) (1984)
Fan Clutch: Description and Operation
Operation
60
Coupling body (secondary member)
61
Pulley (primary member)
62
Flange shaft
63
Sealing ring
64
Needle bearing
65
Cooling fins
66
Oil scraper
67
Compression spring
68
Control pin
69
Bimetallic strip
70
Cover with holding clip
71
Intermediate washer
72
Feed hole
73
Valve lever
74
Reservoir
75
Working chamber
The viscofan coupling is a service-free, hydraulic coupling which operates in dependence of temperature as well as infinitely variable.
When the engine is started (cold start) the fan will initially run at higher speed until the oil has flown back from the working chamber (75) to the
reservoir (74) (approx. 1 - 3 minutes). The fan coupling will then switch off. The fan speed in disconnected condition depends on engine speed, but a fan
speed of approx. 2100/min should not be exceeded.