 | Home > Technical > Defender TD5 Viscous fan noisy on start up. |
 
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| Retrostu Member Since: 03 Feb 2016 Location: Kent (AKA Garden of England) Posts: 128   
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As above really my defender has started to make a noise via the viscous fan when I first started up is this just due to the hot weather even though I haven't used it all day until the evening.
It's never done it before and last time I heard it it was from my range Rover sport which did it for just a moment and then shut up but now my defender has the same issue is this normal do I need to be worried or just a sign that it's working as it should due to the bodywork and engine by getting so warm in the hot sun during the day any advice gratefully received thanks. It's more important to concentrate on what's ahead of you than what you have left behind. This is what I keep watching to remind me why I own/keep my Defender. https://youtu.be/x4DZgOcgn1s |
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28th Jun 2017 6:08am |
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| Clive Member Since: 21 Mar 2014 Location: Littleborough Posts: 467 
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Could be a sign of a failing viscous coupling, I had the same on one of my previous Td5s, it gradually got worse until it locked up permanently, the dealer replaced the viscous fan under warranty.
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28th Jun 2017 1:20pm |
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| Retrostu Member Since: 03 Feb 2016 Location: Kent (AKA Garden of England) Posts: 128
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Right we are then to be honest I did remove fan to do a coolant change to get to get to pipe clip easily maybe I have disturbed something on the fan when I removed it.
But I do seem to remember being very careful with it and placed it carefully on a cloth but maybe it's just one of those things you disturb them they go wrong or break so just by a new fan itself then?. You reckon the spring inside fan is now kerput?. It's more important to concentrate on what's ahead of you than what you have left behind. This is what I keep watching to remind me why I own/keep my Defender. https://youtu.be/x4DZgOcgn1s |
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28th Jun 2017 2:55pm |
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| Clive Member Since: 21 Mar 2014 Location: Littleborough Posts: 467
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I don't think they're that delicate to be disturbed by removing, they're pretty robust really, lets face it they lead a fairly arduous life whizzing round all the time in the normal course of duty.
The spring part you mention is a bi-metallic thermostat which controls the flow of silicon fluid inside the unit and hence regulates the amount of coupling from the driven shaft to the fan itself. Unless it's physically damaged or broken I doubt it will be the cause of your problem. The heat of the sun should have little or no effect on it - unless you live somewhere near the equator 
To be honest, I'd just leave it for now and see how it goes, if it gets worse or locks up altogether then it's time for a new one. |
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28th Jun 2017 3:34pm |
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| Retrostu Member Since: 03 Feb 2016 Location: Kent (AKA Garden of England) Posts: 128
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Nice one Clive cheers now I understand completely, one of my friends said to check the fan when engine cold and it should spin freely, when engine warm should have resistance, so I'll keep a check on it and yeah replace if it locks up, their not that expensive and I have the tools to change so no biggie, thanks again. It's more important to concentrate on what's ahead of you than what you have left behind.
This is what I keep watching to remind me why I own/keep my Defender. https://youtu.be/x4DZgOcgn1s |
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28th Jun 2017 4:02pm |
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| miker Member Since: 13 Sep 2015 Location: Surrey Posts: 1763 
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Mine does it on hot days. Engine bay temperatures in the sun will get pretty high. Once there's a bit of air flowing through it cools down and quietens down
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28th Jun 2017 6:27pm |
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| Retrostu Member Since: 03 Feb 2016 Location: Kent (AKA Garden of England) Posts: 128
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That's when mine makes the noise when it's been parked in sun all day plus my XS is all black so reckon the heat is radiated in the engine bay too. It's more important to concentrate on what's ahead of you than what you have left behind.
This is what I keep watching to remind me why I own/keep my Defender. https://youtu.be/x4DZgOcgn1s |
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28th Jun 2017 7:36pm |
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| Retrostu Member Since: 03 Feb 2016 Location: Kent (AKA Garden of England) Posts: 128
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Mate of mine said try turning fan when the engines cold, should spin freely, when engines warm slight resistance.
Well when it's cold it turns half a revolution freely then stiffens up for the other half of the turn and so on. Stiff, free, stiff, free. When it's warmed up it has constant slight resistance, so now I really am miffed. It's more important to concentrate on what's ahead of you than what you have left behind. This is what I keep watching to remind me why I own/keep my Defender. https://youtu.be/x4DZgOcgn1s |
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29th Jun 2017 6:56am |
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| MadTom Member Since: 10 Sep 2013 Location: Olomouc Posts: 622  
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Good working viscous fan is just slowly rotating on running engine, after a short run. And it is possible to stop this rotation by hand - preferable not yours hand, or by a small piece of wood. If not, the viscous coupling is probably too stiff. It is not uncommon with the age of it. Similar problems with viscous coupling getting stiff has Freelander or RR - but they have this instead of central diff. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo
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29th Jun 2017 7:20am |
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| Retrostu Member Since: 03 Feb 2016 Location: Kent (AKA Garden of England) Posts: 128
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Right we are then 'madtom' thanks for that too I may as well just replace it then it's done is it better to get the whole fan or just the coupling itself and fit it too the fan or is their a worth wile upgrade while I'm on it?. It's more important to concentrate on what's ahead of you than what you have left behind.
This is what I keep watching to remind me why I own/keep my Defender. https://youtu.be/x4DZgOcgn1s |
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29th Jun 2017 2:05pm |
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