thanks for the people who gave advice on viscous fan

[andycook]

as title -

i was asking about viscous fan a few weeks back,
dismantled the fan clutch today, cleaned out the gloopy dark-golden silicone fluid, refilled the unit with new fluid from model shop (3000 wt),
but the thing back together
took the 4runner for a test drive and fan had a nice roar that didnt cut-out after 5 seconds!

so thanks for the advice - it seems to be fixed

andy

[andycook]

fan stay's on all the time now - maybe I put too much silicone fluid in it!

[rich]

oops! Sounds like it.

R.

fan stay's on all the time now - maybe I put too much silicone fluid in it!

[Smokin]

thinking about doing the oil in mine when the big service gets done - we have a big model shop near me - what and how much would i be asking for (so i dont look too much of a pratt when i have to get served by one of my ex pupils!!!)

cheeeers

Chris

[andycook]

I was told silicone fluid - 3000wt
But I wasnt sure how much was in a bottle, I put 2-1/2 bottles in,
as people said for toytoa silicone fluid @18ml per bottle,

turns out the bottles i got have 50mls in them.......
so ive put 2 1/2 times too much fluid in...
as it should be 50ml
explains why fan is always on now, off out to the garage now to remedy that..
andy

[andycook]

poured some fluid out, about 50-70ml, so it should have 50ml ish in the fan clutch now,
put it all back together,
fan stiff when cold, it roared for a while, then cut out
turned off engine, spun very easily...
so back to square one...

think i will shove more silicon fluid in and leave it so its stiff to spin when cold and hot, meaning fan on all time - must be a safer bet than it not coming on when engine hot?

[da SLUG man]

poured some fluid out, about 50-70ml, so it should have 50ml ish in the fan clutch now,
put it all back together,
fan stiff when cold, it roared for a while, then cut out
turned off engine, spun very easily...
so back to square one...

think i will shove more silicon fluid in and leave it so its stiff to spin when cold and hot, meaning fan on all time - must be a safer bet than it not coming on when engine hot?

it has to get pretty hot... mine very rarely comes on... only if the temperature gets above half way and then you only notice it when accellerating because of the loss of power and the noise... as long as the temperature is ok i shouldn't worry.

[andycook]

the whole mthing that started me off looking at the fan was the engine getting too hot a month ago, and coolant overspilling - and i never heard the fan kick in when it got hot

andy

[Vagrant No2]

Andy

The principal of the viscoius fan is that as the engine gets hotter the air flowing over the viscoius coupling warms the bi-metalic spring in the coupling and the oil inside begins to 'lock' the fan to the coupling . This gives the roar sound upon revving . As the fan cools the engine due to drawing more air through the rad it 'unlocks' the coupling . The cooling fan should NEVER fully lock or be locked as the fan can shatter as they are generally larger then the old fixed fans used before . Also the air drawn through is more then a fixed fan as the coupling will allow to slip at high revs . The cooling fan on cars is only of use up to 30-35 mph , after that normal 'ram air' effect is used by the speed of the vehicle naturally forcing air through the rad .
Thats wot I learnt in my apprenticeship and thats how I understand it !

Rick