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Old 28-01-2012, 08:14 PM   #6
shane@mbtech
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Quote:
Originally Posted by shimmy View Post
How and when does the clutch fan run? What is its purpose?
The viscous fan?

If you mean this then it kicks in when temp rises, the hotter it gets the more the fan engages and the faster it cools. But it only pulls air through the rad. At speeds above 10-15 mph the fan is redundant. Its more for stationary purposes. Usually licks in 70-80*c

Its not electronically controlled, it uses a fluid which changes the "clutch" slip when the temp changes, it has a thermal spring which allows the fluid to move from one section to another, causing the fan to engage. The viscous fan is attached directly to your water pump.

Race cars will remove the viscous so there is less rotational mass for the crank pulley to turn. Similar theory to your pulley upgrade you did.
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