Jim Grant's Tech Tips
'94 Mercedes C280, Clutch Fan Operation
Q:
How can I verify if my newly installed viscous fan clutch in my 94
C280 Mercedes is operating OK? Would the clutch be engaged even at cold
temperature at low RPM? When does it kick-in/kick-off? I just replaced
my old one which was too noisy (always engaged) with a brand new one from
the dealer. I don't see any change. Please explain as much as you can.
-
David H.
A:
Heres the basic description and operation of the clutch fan for
you Mercedes. Cut-in Temperature at a specified airflow temperature from
the radiator acts on the bimetal of the viscous fan clutch. The hot air
causes the bimetal to alter its shape and cause the cooling fan to lock
in. The change in airflow is easily heard as it occurs. When operating
correctly you will hear the fan change based on the airflow temperature
over the radiator. There is an oddity on Mercedes clutch fan, which
you may not know about. When you received the clutch fan, it should have
been boxed in a special way. Why is that? The temperature controlled viscous
fan clutch must be transported in the upright position. The viscous clutch
may be placed down on its flange side for a short period for assembly
purposes, but should never be placed with the front down! If this procedure
is not followed, you could easily create new or recreate existing problems.
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