Viscous fan cuts in too soon

raywin · Oct 26, 2014

I have suspected for some time that my cooling fan is running too much, and I think that it kicks up some vibration when the engine is at higher revs.
When I start the engine it seems to be blowing quite hard, but if I spin the fan by hand for about 15 seconds with the engine stationary it seems to free off, and if I quickly start the engine the fan is freewheeling, the difference is very obvious, problem is i can hear it kick in and start to blow after about 3 or 4 minutes ticking over while the engine is still cold and top hose haven't even started to heat up.
Thinking about getting a new one has anyone used the Bearmach one? Any recommendations? Don't want to wast money on a poor quality one but the LR one is a bit expensive.

v8landyman · Oct 28, 2014

raywin said:
I have suspected for some time that my cooling fan is running too much, and I think that it kicks up some vibration when the engine is at higher revs.
When I start the engine it seems to be blowing quite hard, but if I spin the fan by hand for about 15 seconds with the engine stationary it seems to free off, and if I quickly start the engine the fan is freewheeling, the difference is very obvious, problem is i can hear it kick in and start to blow after about 3 or 4 minutes ticking over while the engine is still cold and top hose haven't even started to heat up.
Thinking about getting a new one has anyone used the Bearmach one? Any recommendations? Don't want to wast money on a poor quality one but the LR one is a bit expensive.

Just remove it and fit an electric fan if you need to do heavy towing or cross the Sahara. Removed mine and it never overheats.

Littelwill · Oct 28, 2014

v8landyman said:
Just remove it and fit an electric fan if you need to do heavy towing or cross the Sahara. Removed mine and it never overheats.

Sorry to hijack, so your saying you can run without a viscous fan? (Mines just packed up looking to replace)

the_wolf · Oct 28, 2014

You don't need the viscous fan if you want to fit an electric but I wouldn't take it off just for the sake of it.

OP, the fan shouldn't spin freely when the engine is cold. If it does then you need a new viscous coupling. The viscous fan will spin constantly when the engine is running and when it heats up it will spin more freely and in turn much faster

blue beasty · Oct 28, 2014

Lots of folk run tdi's without fans but not sure about Td5's

Cooking a Td5 is a very expensive game

blue beasty · Oct 28, 2014

the_wolf said:
You don't need the viscous fan if you want to fit an electric but I wouldn't take it off just for the sake of it.

OP, the fan shouldn't spin freely when the engine is cold. If it does then you need a new viscous coupling. The viscous fan will spin constantly when the engine is running and when it heats up it will spin more freely and in turn much faster

Er, int that a bit confuddling? The fan should be able to be stopped with a rolled up newspaper when cold but not when the engines hot.

Makes more sense in my head anyway

the_wolf · Oct 28, 2014

blue beasty said:
Er, int that a bit confuddling? The fan should be able to be stopped with a rolled up newspaper when cold but not when the engines hot.

Makes more sense in my head anyway

I wouldn't stick my hand in it anyway lol. But nope not confusing, the fan won't spin freely with the engine off. If it does then it's buggered. Pretty simple

blue beasty · Oct 28, 2014

the_wolf said:
I wouldn't stick my hand in it anyway lol. But nope not confusing, the fan won't spin freely with the engine off. If it does then it's buggered. Pretty simple

It's the spinning freely and spinning more freely that confused me

To be fair it doesn't take much

the_wolf · Oct 28, 2014

blue beasty said:
It's the spinning freely and spinning more freely that confused me

To be fair it doesn't take much

Those eyebrows are taking over your cognitive thinking. Go have a lie down and ill call Rachel to get the hot wax on standby

Littelwill · Oct 28, 2014

When you rotate you viscous fan by hand it should feel stiff and only rotate under gentle force. if you fan rotates pretty freely or you can spin it round and round its had it and will need replacing.

My fan has died and was looking at just removing it..

v8landyman · Oct 28, 2014

Littelwill said:
When you rotate you viscous fan by hand it should feel stiff and only rotate under gentle force. if you fan rotates pretty freely or you can spin it round and round its had it and will need replacing.

My fan has died and was looking at just removing it..

I would just remove it, especially with winter about to start. If your cooling system has always had the correct concentration of OAT antifreeze there should be no problem. The system has a considerable over capacity, being designed to cross deserts. You could think about fitting an electric fan next Spring.

Littelwill · Oct 28, 2014

Thanks for the advice. I wasnt sure if it was a good idea to just remove it.

raywin · Oct 28, 2014

blue beasty said:
Lots of folk run tdi's without fans but not sure about Td5's

Cooking a Td5 is a very expensive game

I have this feeling too and that is what worries me thinking about running with no fan, I took the fan off on Sunday and ran about 5 mls temperature gauge seemed to say things were as normal and the engine seems slightly more responsive ( maybe I just wanted it to be).
Also thought about using a Mondeo electric fan, looking at the current viscous fan it must absorb about 2 to 4 Kw depending on engine revs and the electric fan seems quite attractive.
I agree the cooling system is quite robust, but it kind of nags at you thinking about the price of TD5 heads.

A good Viscous unit should be freewheeling when the system is cold and I am drawn to buying the Bearmach one and keeping the electric option open for a later date.

raywin · Oct 31, 2014

So I received the fan yesterday and fitted it. It was driving at first but then there was a change in the noise level and it started to free wheel as it should feels better without the extra load on the engine and lower noise level is always welcome.
So the fans can fail in two ways either they don't cut in or as mine did they drive all the time, probably worth checking now and again.

DiscoJoe · Oct 31, 2014

@ raywin

Don't forget that the temp gauge isn't properly analogue like on the Disco 1. It only has four positions - cold, warming up, normal and too late ☺

If you really want to see the actual coolant temperature then plug in a nanocom or get a proper gauge.

Ruari · Nov 17, 2014

And what is the correct temp. for the td5 to run at?
I run mine without a fan only because I haven't got round to replacing it.

Has anybody got the wiring diagram for the electric fan. I could fit a relay and my owner power supply, but if half of it is present ...

Jason2 · Nov 27, 2014

I run mine in France 80% of the time even towing and have never had any problems. I put it on though in summer when it's very hot just in case !

sierrafery · Nov 27, 2014

Jason2 said:
I run mine in France 80% of the time even towing and have never had any problems. I put it on though in summer when it's very hot just in case !

but do you have a gauge fitted?...cos if not you can run it at over 100 untill 110*C without even knowing it for long journeys and it will come the time when you'll end up with a cracked head, provided you have a working aircon/engine cooling fan which kicks in at 110... as stated before the car's gauge is not well conceived, it stays on the middle position between 70 and 120*C, when the gauge goes up from the middle at 120*C it's about too late...it's not healty to do that even if you was lucky untill now, at least fit a 10 quid temp gauge which is easy to fit to be on the safe side

Jason2 · Nov 27, 2014

sierrafery said:
but do you have a gauge fitted?...cos if not you can run it at over 100 untill 110*C without even knowing it for long journeys and it will come the time when you'll end up with a cracked head, provided you have a working aircon/engine cooling fan which kicks in at 110... as stated before the car's gauge is not well conceived, it stays on the middle position between 70 and 120*C, when the gauge goes up from the middle at 120*C it's about too late...it's not healty to do that even if you was lucky untill now, at least fit a 10 quid temp gauge which is easy to fit to be on the safe side

I can see where you are coming from matey and appreciate the advice

I must be bloody lucky then as I have been doing this for over 6 years with a TD5 auto Disco & a 110 Defender towing 3ton+ trailers and gauges have never moved a nats dangly bits !

sierrafery · Nov 27, 2014

you was warned

... i've just replaced the head on mine with a new AMC one as i found it cracked at 235.000Km, being suspicious i fitted a gauge after that and i observed that the engine is running over 105 without being more than 20*C outside...i dont even know since when it's been doing that so off course i started the investigation and found the viscous fan freewheeling with hot radiator so like it wasnt there, fitted a new one and now it's running nice around 89 all the time... there is the possibility though that it cracked for ather reason, i dunno

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