Viscous fan always on

[grantw]

Hi All,
As per thread title my viscous fan is always on and roaring like a jet engine. I can't find much online as to why they get stuck (It's all about them not working at all) so I'm just asking on here for what to look at once I take it off. From my research so far they re quite simple - just the bi metallic strip and then the 10000 cst oil internally. If the strip/coil is seized/rusted is it possible to replace these or is it a whole fan/clutch replacement?

Will update with pics once I get it off.

Thanks

 

[Rich Sims]

Will it spin by hand when engine stopped?
has it just started?

Could ld be the spindle that the bimetallic coil is attached to that controls the lock up seized. Which you can un seize but be carefully with the coil.

If locked normally means too much oil or bearing sized inside.

 

[grantw]

Yep still spins my hand .. and it doesn't seem all that stiff. I'm not sure when it started so I'm guessing it's one of those things that build up slowly and I didn't really notice it until Rob pointed it out to me ... and now it's all I hear!

 

[Rich Sims]

Still could be the shaft seized which is controlled by the bimetallic coil then. You should be able to turn it with a pair is pliers. Or heat it with a hair dryer and watch it turn.

 

[grantw]

Thanks i'll give that a shot tomorrow.

 

[wobbly]

Hi Grant

There was a long running thread either here or on the other site about this very problem - as I recall it was a guy in Africa with a petrol Collie. Will see if I can find it for you, but as I recall the oil was the issue, needing changing.

Pete

 

[grantw]

Thanks guys.

Just had it out and was hoping all the dirt as shown below was causing it to be stuck ... but no such luck. have new oil on order 60ml of 10000 cst.

 

[grantw]

I ended up taking the lazy way out on this. I bought a new fan clutch for £90. Problem sorted.

So now I have a spare that I'll take apart to see what was going on.

 

[Shayne]

I would be interested in what you find when you take the old one apart Grant as i'm thinking the lazy option is the best one as well .

 

[grantw]

Me too Shane. Half the reason I went brand new was just knowing I will get the factory preset reliability back on such a crucial component.


Sent from my iPhone using Tapatalk

 

[clivehorridge]

That was my solution too, but admittedly, that was before joining the forum and finding out that they're servicable.

TBH, even in the hot weather here (40 C +) I find my 80 fan doesn't kick in, but the truck doesn't overheat. A couple of months ago I was scrabbling up a steep and vey slippery mud slope, and I found the optimum grip effect of my tyres in low 2nd, at about 3,200 rpm. It took me about 15 minutes to climb about 200 m of track (no trees to winch off, nothing) and just before the top, my fan kicked in. It gave me a fright because I'd never heard it before.

Anyway no overheating issues, and it was reassuring to know the thing was working!

My system never loses a drop of coolant, the level is constant in the reservoir and I check it every week. I'm well pleased with it

 

[Shayne]

New oil V new everything for 90 quid did you get the Aisin from Roughtrax Grant ?

 

[grantw]

I did Shane.