Viscous Fan

[Erik]

Hi Guys

I need to understand how does a Viscous Fan work from what I understand is that it is free to move when engine is off ( move it by hand) but feels as if it has a drag on it.

When engine is running it will run at the same speed
and when something slows it down ie water it should slow down or stop.

I need to work this out because this should have not have happened to me on Saturday the Fan breaking off all its fins and destroy the radiator

Thanks Guys

[Spike]

Erik the blades of the fan are flexible and bend forward in the water and hit the radiator.

When they heat up the goo inside stiffens and acts as a clutch.
I don't like them. They rob you of power at normal driving speed when they are not needed, and don't pump enough air when you are crawling at idle. Viscous fans are only nice if you tow regularly.

An electric fan engages only when needed, with the added bonus that you can switch it off with an overide switch when wading. And if you are concerned about having enough air you can add another smaller "pusher" fan on the front of the radiator.

[Engel]

We have bakkies not boats!!

Agree with Spike. Electrics are the way to go but still see a lot of RWD vehicles like bakkie having them

[Erik]

Thanks Spike

But why would the blades break if I look at the new one and whats left of the old one there is diffrence in the color. older is more yellow

You can even feel the diff between the 2, possible that the older one got brittle.

I need to go back and find the rest of the fan in the dam

[RogerL]

Discussed it on the other side, but in my Ford Courier, the visco fan packed up and we started to run hot under load. Apparently the oil has a limited life, and then throw the unit away and buy another.

The visco fan is also supposed to not put that much drag on the motor like a fixed fan does - it delivers just as much air as the engine needs, is quieter than the fixed fan etc.

When mine packed up, for R54 and about 1/2 hrs work, I fitted the fixed fan through an aluminium adaptor. Never looked back, and cooling is now better than before.

[Erik]

What Im finding aswell is that when idleing its a bit rough I can feel a vibration but as soon I pull away or take the revs up a notch or two it goes away.

May 2007 better get here fast its trade in time

[benhur]

I am with spike and the guys about electric fans. Mechanical fans steal engine power. If you look at the latest trend whith Hi-tech efficient engines, guys like BMW now even have the water and oil pumps running of electric motors which can be controlled to pump (enough) when needed without stealing unnecessary engine power.

I am looking for advice on electric fans. Is there a recommended, good quality, after market fan?

[Spike]

Check Flex-a-lite fans in the States. They have a huge range and have plenty info on their site to help you choose flow rate etc.

Spike, thanks for the advice. I will have a look at their info. Keith

[Ian PR]

A viscous fan also engages only when you need it -


Heres how it works

http://www.roversd1.nl/sd1web/viscofan.html