Hi!

As the title says the large fan that sits between the engine and radiator , driven by the belts is always running on my see even when very cold , does this mean the viscous clutch??? In the fan needs replacement, as I was led to believe these fans should only be engaged at a certain temperature. The fan can be moved by hand when the engine is not running so is not completely seized , sorry for any poor terminology here Haha!

 

As always many thanks :)

The viscous van is supposed to be turning constantly with the engine. It contains a wax substance and a spring, the temperature of this depends on the fan speed in relation engine speed. Kinda like a gear in a way.

You should be able to stop it with a piece of card on a warm engine. If you can't then it's seized.

sounds fine to me

Okay I'll give that a go, just get a lot of air noise from the fan especially noticeable at lower speeds , would just be nice to try and reduce that a bit ,

Thanks!

Just don't use your hand. I know someone who lost a finger to the fan...

Based on a bimetal sensor located at the front of the viscous fan the sensor expands or contracts, depending on the air

temperature flowing through the radiator.

 

At Cold Temperatures the bimetal sensor contracts closing the valve, so the silicone fluid remains in the reservoir chamber.

At this stage, the viscous fan coupling is disengaged and turns at around 20% of the rotation speed of the engine.

 

 

At operating Temperatures the bimetal sensor expands, rotating the valve and allowing the silicone fluid to move through

the entire chamber to the outer edges. This generates enough torque to drive the cooling fan blades at engine operating

speeds and remain at a consistent temperature. At this stage, the viscous fan coupling is engaged and turns at around

80% of the rotation speed of the engine.

 

 

Source: BG Automotive

That's a nice cutaway drawing, I knew what they did but didn't know how it actually did it