> << The viscosity of the fluid clutch increases as the temp behind
> the radiator rises. If the clutch doesn't get as hot, the fluid
> won't get as thick and the engine won't have to work so hard
> to turn that windmill. >>
>
> WRONG!!
> The viscous coupling fluid does not change viscosity with temperature (at
> least not with the intent of spinning the fan). The fan is basically a pump
> internally. On the front of the clutch is a Bimetal element shaped like a
> spring. The center of the element is attached to a small shaft. As the
> element heats, it twists the shaft which is attached to a valve inside the
> clutch. As the valve closes, it causes more restriction in the fluid path,
> and therefore more engine torque is passed on to the fan blades.
>
NOW when the fan is cold as in when first started, the fluid IS THICK and causes
the fan to turn fast even though the valve is open. After a minute or 2 the fluid
warms, becomes thinner and since the valve is open the clutch free wheels.
Thetas is why the cold fan noise. It is NOT a malfunction therefore no one is
required to fix it. Dodge is not the only make whose fans do this. Every Ford or
GM I ever owned did this too. Learn to live with it. If you have a clutch fan
and it is working normally it may do this. If the clutch is worn out it may get
quiet but now you got other problems to worry about besides a minute or 2 of fan
noise when the engine is cold.
Jim Miller (26 years in a radiator shop)
Waco, Tx
Still Dakless (only God knows where my truck is)
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:08:54 EDT