ManwithSupra Posted August 29, 2011 Share Posted August 29, 2011 Wondered if someone could enlighten me on the operation of the viscous fan. I replaced my viscous coupling yesterday as my other one kept locking up when the engine got hot. Took the car out again today and gave it the beans, however after parking up I am getting the rushing sound of a fully engaged viscous coupling as before. Now I am starting to think this maybe normal operation. But could someone enlighten me on the operation? When the car gets hot is it supposed to run the same speed as the engine? or have I just gotten unlucky with a 2nd hand one. Don't want to really buy a new coupling off Toyota and find the ones I have were fine anyway. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted August 29, 2011 Share Posted August 29, 2011 Sounds quite normal to me. Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted August 29, 2011 Share Posted August 29, 2011 Thats normal, the fluid inside thermosets, so as the temp increases the fluid becomes more viscous Quote Link to comment Share on other sites More sharing options...
ManwithSupra Posted August 30, 2011 Author Share Posted August 30, 2011 Thats good news then - cheers guys Quote Link to comment Share on other sites More sharing options...
Kaan W Posted July 23, 2013 Share Posted July 23, 2013 Just going through a check on my car with all the cooling components I thought I would ask here about my fan. Should the fan be stiff to spin by hand when the engine is turned off but still hot (90 degrees)? I'm not sure if I'm getting correct lock up when the engine is hot as I can still spin it freely when the engine is pretty hot. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 23, 2013 Share Posted July 23, 2013 There should be some resistance, yes, but not so you have to use much effort. You shouldn't just be able to flick it and spin it though. Usually if the viscous fails they either lock up (seize) or leak silicone fluid. Modern ones are pretty reliable! You do NEED that shroud, will make at least a 70% increase in air throughput. Can't stress that enough.... Without a shroud the fan will draw air from the easiest path, which is NOT through the rad core. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted July 23, 2013 Share Posted July 23, 2013 There should be some resistance, yes, but not so you have to use much effort. You shouldn't just be able to flick it and spin it though. Usually if the viscous fails they either lock up (seize) or leak silicone fluid. Modern ones are pretty reliable! You do NEED that shroud, will make at least a 70% increase in air throughput. Can't stress that enough.... Without a shroud the fan will draw air from the easiest path, which is NOT through the rad core. Well theres no fluid leaking and it's not seized but it spins for a couple of seconds if I spin it by hand so it should be ok. Ive got a shroud on its way to me soon so this should solve everything. Thanks for the help Chris. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 23, 2013 Share Posted July 23, 2013 It certainly should NOT spin for a couple of seconds, it should stop almost immediately if you flick it round from stationary. Looks like it needs a new viscous coupling. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted July 23, 2013 Share Posted July 23, 2013 It certainly should NOT spin for a couple of seconds, it should stop almost immediately if you flick it round from stationary. Looks like it needs a new viscous coupling. Ok I will check again just to make sure then order another one if it seems to spin more than it should. Also the new fan shroud comes with 2 small electric fans but I only have a wire for one fan on my car, can I wire these both to the same wire or a manual switch inside the car? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 23, 2013 Share Posted July 23, 2013 I would need to study the schematic to see how Toyota wired these. I know at least one comes on with the air con, and probably also if the temp switch in the bottom rad tank switches. I haven't time to dig them out and look at the moment, sorry. If you can find them and post the relevant section I'll try and have a look for you if you can't read it yourself. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted July 23, 2013 Share Posted July 23, 2013 I would need to study the schematic to see how Toyota wired these. I know at least one comes on with the air con, and probably also if the temp switch in the bottom rad tank switches. I haven't time to dig them out and look at the moment, sorry. If you can find them and post the relevant section I'll try and have a look for you if you can't read it yourself. No worries I have the manuals to hand now ill have a look. Quote Link to comment Share on other sites More sharing options...
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