 | Home > Maintenance & Modifications > Thermostat electric fans v engine driven ones |
 
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| lambert.the.farmer Member Since: 11 Apr 2012 Location: harrogate Posts: 2006   
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There seems to be a vast amount of anecdotal evidence pointing in both directions but i have yet to find any remotely scientific impartial research on which to base a conclusion. Consequently i choose to stick with a viscous engine fan as that is one less mod to bother the insurance with. Rhubarb and custard let fly with their secret weapon.
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18th Jun 2013 9:15pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7695 
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it depends on what your doing and on what vehicle. you mention a diesel def but talk about a series petrol which is then scrapped, i am not quite seeing the link. (edited to add - just seen the link the s2 has an electric fan running when upside down!)
i run a TGV with a viscous fan as its always there, its reliable and pretty much guaranteed to work when needed when the engine is running (viscous and belt failure aside) my puma runs a viscous my 200tdi runs a viscous chance of failure is slim, they have massive reserve capability, but they do means it takes longer to warm up the vehicle and can take some oomph. i also run a TGV with a rear mounted rad with twin Spal 11" fans. viscous was obviously not an option. they work well, i believe 2 fans are better than one if wired correctly. keep the vehicle at 80deg C (TGVs are renown for running hot normally) if you run one electric fan it will need a good supply, the one i had on a 300tdi 110 needed more than 30A on start up. they still load the engine, just through the alt, but load is probably less. warm up time is improved. failure - fan mountings/cowls to cause contact with rad is well known. some brands fit through the rad mountings which can wear through the rad fins, fuses failing, motor failing, electrical dash switch failing, any electrical connector coming off, thermostat control unit failing, user forgetting to turn on, relays failing, feed failing can all lead to the electric fan not working If you run with two fans side by side mounted then always have them both on together other wise one fan can draw air through the other stationary fan rather than the rad. you can wire them to work at different speeds from say two temp senders (like the X-Eng X-Fan system) if your doing alot of wading you may want to consider an off switch for them (also helps if debris has become fouled in them - switch off rather than blow the motor) personally on the one i run it has a 3 way switch thermostatically controlled/Off/Perm On. both fans are wired to work together. i run an X-Fan as they are reliable, and dont leak. Ford Mondeo fans with cowl work well. or you could try a vehicle's a/c fans. dont Discos etc all run electric fans only? Cheers James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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18th Jun 2013 9:15pm |
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| IKke Member Since: 16 Aug 2008 Location: Brabant Posts: 117  
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Mine has an electric fan, previous owner fitted it. Seems to work fine but still takes ages to warm up properly
Fuel usage does seem to be lower than most defenders, but i think that has more to do with a lot of other factors than the fan. Scaling the real deal. |
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18th Jun 2013 10:18pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7695
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what were your thoughts Richard? Cheers
James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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24th Jun 2013 7:46pm |
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| BigWheels Member Since: 21 Mar 2010 Location: Somerset Posts: 1405  
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I was considering twin smaller fans, rather than 1 large one. Is there room for any electric fans to be fitted in addition to the OE one?
In the summer, with a warmed up winch & 2 lamps in front of the radiator, I was concerned about sufficient cooling for engine & also helping the a/c. But in winter, or whenever electrics might be risky, the electric fans can be switched off... So I want the best or both worlds, for not too big a budget.  Land Rover Defenders. 67 years heritage, minimal appearance changes, still going strong all over the world. Not a fashion vehicle, but fashionable to own. Made for the needy, not the greedy. Ta ta Defender |
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24th Jun 2013 8:58pm |
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| chopcat Member Since: 11 Sep 2012 Location: Pembrokeshire Posts: 409  
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I fitted one before we went to morocco. Was told by the experts ( highly regarded in LR circles) guiding us to take it off before we started as they always have problems with electric fans overheating in the desert.
Dont know if they were right as i put the viscous back and we had no problems. The kenlowe now does a good job on the Marcos instead. Cc |
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24th Jun 2013 10:53pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7695
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the std viscous is more than adequate for your use in the summer. don't forget the climate testing they have undergone. Cheers
James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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25th Jun 2013 8:52am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16892 
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One advantage of electric - which, incidentally, I would always fit with a kill switch - was that you can turn them off if wading in deep water, which was especially useful in a petrol-engined vehicle.
On my Series 1 it was always my intention to fit an electric fan in this way, but after mastering the art of getting the fan belt adjusted just right to slip when wet and grip when dry I never bothered. (Old folk like me will remember that the classic problem on Series vehicles is that if the fan is submerged it screws its way forward into the radiator). |
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25th Jun 2013 10:22am |
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| tacr2man Member Since: 02 Oct 2008 Location: J10 M40 Posts: 20 |
The viscous fan doesnt have any drawbacks in reality, it has more power to drive the air when cooling is needed, they dont have any problems with use in water, as they freewheel when cool, and dunking them in a creek usually has that effect . They have less things to go wrong , than an electrical set up. The effect of delaying engine warming is minimal in reality , as its the thermostat and heat generation of the engine that is the major factor in that , when driving ram air is cooling the rad , the fan will be freewheeling , thats why you get the roar , and then it goes quiet shortly after starting . If the roar persists then you have a viscous unit fault. JMHE
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29th Jun 2013 6:42pm |
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| BigWheels Member Since: 21 Mar 2010 Location: Somerset Posts: 1405
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Thanks for your advice guys. I've crossed electric fans off my list.
 Land Rover Defenders. 67 years heritage, minimal appearance changes, still going strong all over the world. Not a fashion vehicle, but fashionable to own. Made for the needy, not the greedy. Ta ta Defender |
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29th Jun 2013 7:08pm |
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| theorangebandit Member Since: 03 Jun 2013 Location: Stowmarket Posts: 862 |
In reply to the desert thing the army use viscous becaus dog its ability to work almost continuously, through many problems. I have also found no real evidence to support changing to electric fans. Only bonus would be to be able to control manually the fans in case of over heating while off roading.
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9th Jul 2013 10:23pm |
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| c18rch Member Since: 28 Nov 2012 Location: Sheffield Posts: 28 
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I fitted one to my TD5. MPG went from 28mpg to 32mpg. Throttle response was noticably better. Had it fiitted for 4 years, and I don't think the fan ever once came on. My TD5 was used for general farm driving (fields, mud etc) and towing.
As for being reliable, in ten years of land rover ownership I've had two viscous couplings fail. I've not had an electric fan fail. That said as above, they very rarely if ever come on anyway for normal UK driving. Electric fans for diesels in the UK are imo one of the best mods I've done to my landies. |
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10th Jul 2013 11:30am |
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| landybehr Member Since: 17 Apr 2013 Location: -D- Posts: 173 |
I think the viscous fan willl be able to move more air. I canīt give proof, but several people taught me so, and I now believe that. OTOH the very most of the driving time it is not needed. Think of the winter. And even in summer it wonīt do an important job unless standing in jammed traffic. And that is the condition where I could imagine that the elect.fan can be superior - it is always running at full speed, rather than the viscous one (which turns slow at engine idle) - I could think that this effect could be a benefit even in the desert. Furthermore the elect. fan (maybe) can save the water pump bearing from the load/forces of the mechanical fan.
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10th Jul 2013 7:53pm |
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