 | Home > Puma (Tdci) > Viscous Fan [Vs Electric Fan] |
 
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| zsd-puma Member Since: 09 Aug 2016 Location: Kent Posts: 2720   
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To check the viscous fan is working, with the engine cold. Hold a rolled up news paper in the fan to stop it rotating and get someone to start the engine. The viscous coupling should then heat up and start to lock and push your rolled up newspaper out of the way.
If your engine isn't over heating though, i would suggest it's working fine. If you were in the relatively cold UK, then i would suggest that binning the noisy viscous fan and fitting an electric one would be worth while. But as you're in a warmer climate i would recommend keeping it. Viscous fans are generally much more reliable that electric ones, although more noisy and can over cool in cold climates. |
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30th Nov 2017 5:07pm |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2645 
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Viscous fans are only noisy when they are working hard, in which cases you’ll not hear them much over the engine. They also shift a serious amount of air, hence the noise. When cold they just idle freely and take no power off the engine and will not overcool it at all.
You’ll not get it hot enough to lock up properly in a temperate climate without loading up the engine, only times I’ve been aware of mine kicking in properly has been towing heavy trailers up motorway hills in the summer. The only advantage of an electric fan over a viscous one in my opinion is the freeing up of space in the engine bay for servicing etc. - leave it well alone, Land Rover knew what they were doing. |
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30th Nov 2017 8:51pm |
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| keef9t Member Since: 13 Mar 2016 Location: manchester Posts: 170 
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When I bought my 57 plate Puma it had an electric fan fitted and the viscous fan had been left in the back. When the electric fan packed up I removed it and put the viscous one on. I feel it tows better since and put the improvement down to the fact that a lot more air is passing over the intercooler with a consequential power increase.
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30th Nov 2017 9:39pm |
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| miker Member Since: 13 Sep 2015 Location: Surrey Posts: 1763 
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Agreed on all counts! I only ever hear my fan on first startup on a hot day, when the heat soak has locked up the coupling. As soon as it gets some air flow it quietens down again. Also much easier to remove a viscous fan completely for space than an electric |
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1st Dec 2017 12:31am |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8029  
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Viscous it's the way forward, lr r&d had that right. Unless you have moved the rad to the back or need engine space i would stick with viscous. Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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1st Dec 2017 7:23am |
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| zsd-puma Member Since: 09 Aug 2016 Location: Kent Posts: 2720
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They're noisy compared to an electric fan that's switched off. But perhaps it's more accurate to say an electric fan is quieter when it's not running than a viscous fan freewheeling. Take the fan off (or the belt) and it's amazing how much sound they actualy make.
Strange there is still quite a big market for rad muffs on Defenders.... |
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1st Dec 2017 8:46am |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2645
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I’ll agree to disagree then, when my viscous fan is freewheeling it is not making any noise.
Radiator muffs are designed to be used in extreme cold conditions where the airflow through the engine bay can cause the block to cool excessively - in my experience this simply isn’t the case for the majority of the UK. If you are in a place cold enough where the airflow is over-cooling the engine then a muff may be appropriate, but it’s got nothing to do with the viscous fan as it won’t be operating at that temperature. You’d get exactly the same problem with an electric fan. When the weather is cold here the thermostat will shut off flow to the radiator if it is not needed, and the viscous fan will not be operating. Hence the use of a radiator muff achieves nothing. Despite living in Scotland I’ve never found it cold enough to fall into the category above where a muff would be useful, and that’s with a 200Tdi which is notorious for running cool. Plus the existence of a market for something doesn’t mean they’re actually necessary for most folk. This forum has plenty of evidence of that phenomenon! |
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2nd Dec 2017 10:01am |
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| Arsath Member Since: 20 May 2015 Location: Sri Lanka Posts: 133  
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Thanks Guys!
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4th Dec 2017 10:50am |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410
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Agree entirely with Retro here. Providing your cooling system (pump, fan, rad, pipes, coolant, thermostat, etc...) is all in fine fettle then the viscous fan will barely ever fully engage in the UK, towing or being stuck in traffic during high summer being the exception. I have in the past, albeit on a 200tdi, replaced the viscous with a kenlowe electric fan and installed a (home made) rad muff. The thought at the time was mpg and "heat-up" time. The conversion to the electric fan did not noticeably improve the mpg, neither did it reduce the engine noise, neither did it release any noticeable horsepower. It did however prevent muddy water being sprayed all over the engine bay when wading and probably the only noticeable benefit. As far as I can see fitting an electric fan is probably only a real benefit to those with existing fixed mechanical fans, as in series LRs. The rad muff did nothing to speed up the "heat-up" time of the engine and its only noticeable benefit was as a wading blanket. The best solution for my 200tdi was no fan at all in Winter and kept it strapped to the dog guard for quick deployment during Summer months or hard work. What did effect the "heat-up" time and interior heater temperature was a regular flush of the coolant system and adjustment of the controls. Massive difference. You live and learn. Back to the topic at hand. Asarth. I assume your TDCI is in Sri Lanka with you. So being as everyday will be like a UK equivalent HOT summer's day then your viscous fan does probably engage significantly more often then a UK based fan would. It is entirely conceivable that your fan might need to be replaced as it is being used more often. If you want ultimate cooling reliability and happen to live in the tropics or hotter, then nothing will beat a fixed mechanical fan, as found in Series Land Rovers. If however, you either do not like the sound of a turbine announcing your arrival everywhere and need a reliable (almost) fit and forget cooling method then a viscous fan is the way to go. If you live in a temperate region of Earth then I would still go for a viscous fan, but if you really really really want it, then an electric fan as a poor and increasingly expensive second choice... Incidentally my TD5 has literally just had a full cooling system re-vamp (rad, pump the works) due to a warped head and now heats up quicker, temperature gauge now sits a good 3-4 needle widths towards the blue and cools down quicker as well. Now looking to fit an auxiliary heater either in the coolant system or in the cab to keep warm whilst stuck in traffic. Funny world. Thread - http://www.defender2.net/forum/topic58275.html |
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4th Dec 2017 11:33am |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2415  
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I am wondering how hard locked is the clutch at temps over 90°C. Is it a progressive hardening
 or a sudden increment? Puma 110" SW
............................................................. Earth first. Other planets later |
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23rd Jan 2019 4:18pm |
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| Lodelaner Member Since: 04 Feb 2010 Location: Lambourn Posts: 632 
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From cold a viscous fan will engage for the first 45 seconds - 1 minute (approx) and then disengage. If the fan doesn't operate initially from cold it should be replaced (because the fluid has leaked out usually). A fan will rotate at approx 20% of engine speed when not engaged. If the bimetallic thermostat isn't working you'll only know by it the engine overheating. This is usually a gradual decline in performance though rather than a catastrophic failure on a regularly used car. A car that's been stood is harder to diagnose as corrosion is the prime cause of failure. I believe that a viscous fan is a more simple and reliable device than an aftermarket fan. JB @Lodelaner Instagram Youtube greenlaning and other LR related content |
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26th Jan 2019 2:06pm |
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| Landymatt Member Since: 31 Dec 2018 Location: York Posts: 191
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With the hot weather we've had the last couple of weeks, I think I've really heard the viscous fan working on my Puma, when revs went over around 2200rpm... have to say I like the sound! Reminded me of a Range Rover engine... like a deep whirring / whooshing noise.
Now it's cooled off, no more fan noise  |
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18th Aug 2022 3:15pm |
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| steveww Member Since: 05 Jan 2022 Location: Uppingham Posts: 568 
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During the recent very hot (for the UK) weather, I have heard the fan on my Puma working. This was in slow moving traffic at 35C. The A/C was starting to struggle a bit too, might be due a gas top up.
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19th Aug 2022 9:47am |
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