Viscus fan

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Allen 666

New Member
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136
Location
Henley in Arden
Here is something interesting,As i was under the bonnet looking at modding the EGR..I thought while the plastic is off the engine and rad top i would start up and just have a look as you do,1999 TD5,I noticed that on tick over the cooling fan was not turning i taped it with a screwdriver it went to move but never, i reved the disco and fan moved, tick over stationary..Now i thought it was supposed to turn on slow tick over and slow down with speed,,I oiled it round the center and turned it by hand and now it goes round on tick over so it works.......But if its not been turning for a long time and temp never gone above half way can i just take the fan off and leave it off.Mind you i have read on here how people sometimes remove them but it looks a pig to try and get some sort of spanner down there in between rad and fan well i could not even see a bolt in the middle but i guess there must be one.
 
The fan should spin freely when cold. This doesn`t take any energy from the engine. When hot the viscous coupling locks up and spins the fan. Don`t try putting fingers in there after sitting in a traffic queue in the summer, unless you really want a red engine bay.
 
i would say you need to fit new viscous fan as yours is too loose ,under normal driving probably dont need ir but one hot day stuck in traffic you will
 
better heat control? As soon as your motors warm it runs all the time taking power....the only real temp control comes from the thermostat cutting the rad in and out of the loop. A lecky fan will give you cooling when you need it,which lets face it is not often, taking no power from your motor
 
I think viscous may be better at keeping the whole engine bay at a reasonable temp but it's horses for courses as modern motors are still being made with leccy and viscous units so efficiency can't be too bad. My one can be easily stopped when cold but not hot so power taken when cold is limited to the effort required to turn the blades I.e. Not much.

I took mine off for a while but was too concerned with overheating so stuck it back, difference in warm up time is practically nothing so it must be working right, not worrying about cooking the block in a traffic jam is a big relief :)
 
Hey, you advocates of the Electric Fans, do you realise how much power is taken from your engine by the alternator that has to replace the energy taken from your battery by the electric fan or fans, (because you may need more than one in most cases to do the job that the engine driven fan does). Ye gets nuffin for nuffin, if you did, you would have invented "perpetual motion" and I dont think thats been perfected yet. If the viscous unit is functioning as per design IT is the best for the job. The accessories sellers will sell you all the useless junk you will buy and then some, "stick with stock" and yer can't go wrong, some engineer did a lot of design work to keep that donk cool.
 
Here is me thinking that a viscus fan only ever run when the engine was at tick over and stopped, when the revs went up the fan slowed down,So what should be happening ,Lets say that you get into the disco on a cold morning start up the fan will Not turn at tick over due to every thing being cold........But lets say i drove 20 miles left the disco running at tick over again,I now looked at the fan and it will be running because every thing down there is hot...( ps im only talking about tick over fan movements)
 
When cold the fan should be stoppable, by a rolled up newspaper, (NOTyour hand). When hot it will be much harder to stop, (hands clear again).
When dragging a heavy up a hill in Spain in the summer you should hear see the temp gauge slowly rise above normal,then about 3/4 ofway up there should be a noticable roaring sound as the fan fully engeges, and the temp gauge should the drop. Fan workng well. This last test is at your expense not mine.
If engine warms quickly and doesn`t over heat, don`t worry.
 
thermostat once engine reaches running temp stays open,you get a better smoother heat control with viscous ,which is better for the engine as the engine parts expand and contract more gently ,especially on warmer days, not a problem at the moment admittedly ,new viscous isnt dear i think 5 or so years between new ones not bad
 
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