Viscous Fan Confusion?

[hellmett]

Hi All,

Using this excellent guide,

http://www.hiluxsurf.co.uk/showthrea...hlight=viscous

I replaced the oil in my viscous fan with Silicone 10,000 WT (to make it run a bit cooler).

When I disassembled the coupling it was nearly empty with only some residual oil there so it was completely useless!

AHA, I thought! This is going to fix my overheating problems!

My confusion is, after replacing the oil with 'thicker' silicone oil it still seems to move quite freely?

I read here that when the engine is up to temp the vicous fan is quite stiff and difficult to move, is this so?

Mine is just the same, it can be turned freely even when the engine is hot!

Is my coupling FUBAR?

Gary

[Albannach]

The fan will move reasonably freely when cold; it will still move, but be much stiffer, after it's ben for a run. It will still be 'free' if the vehicle is warmed up without giving it a run.

[Hawaii]

Helmutt

if the coupling was empty when you started how much silicon oil did you put in?????

When I did mine, it was also empty (apart fom a really tiny bit of residual gunk) I cleaned that all out and ended up putting 3 bottles (75mls in total) in to get it spinning when cold but stiff when hot (ohh-err missus)

If you haven't put enough in then it will spin freely all the time and not pull the air thropugh as it won't lock up when hot

hope this helps

hawaii

[hellmett]

re

I bought x2 50ml bottles and I used a full one and half of the other so I guess about 75mls.

I done everything right so can't imagine why the fan isn't as stiff as I thought it would be?

I can deffo hear it spinning and shifting air now so I suppose it is better than before!

As far as temps go, it still runs at about 96 degrees C and the true test will be later when I attempt the massive hill on the way to work that overheated it last time.

The fan 'pulls' air through the rad, right?

Gary

[Sir Plug]

I bought x2 50ml bottles and I used a full one and half of the other so I guess about 75mls.

I done everything right so can't imagine why the fan isn't as stiff as I thought it would be?

I can deffo hear it spinning and shifting air now so I suppose it is better than before!

As far as temps go, it still runs at about 96 degrees C and the true test will be later when I attempt the massive hill on the way to work that overheated it last time.

The fan 'pulls' air through the rad, right?

Gary

If you can hear a deep roar when revving the engine hot, then the viscous is working. Next step is check the radiator (no obstructions) and possibly flush it. Followed by a new thermostat. I always fit the Prado thermostat. It runs cooler than the Surf. I have one in mine and we have some pretty mountainous terrain where I live. The Surf very rarely goes over half way, when I climb over them, flat out in full Summer heat! Part number for the Prado stat is 90916-03121

[schrodingers-cat]

Whangaparaoa. Just had to Google that name. That looks like a well nice place. I could live there

[Sir Plug]

Whangaparaoa. Just had to Google that name. That looks like a well nice place. I could live there

Indeed...a stunning place. I live on the very narrow piece between the 2nd and 3rd large masses, sea views from all windows. The whole peninsula has a little micro climate that never drops below 16c in Winter!

A bit different from Mansfield, Notts, my last home of many years!!

[Hazzo]

I reckon you need to do a full flush, change the stat, even for the 82 deg one as your running hot and I see your not in the tropics, mine has an aftermarket guage now after the other one never moved when the head popped, it never goes higher than 90 regardless what hill I go up, I reckon you either have a dodgy stat/rad cap or system blockage.

One bottle is enough for the viscous and I reckon it needs doing 2 yearly the same as the coolant, our temps are similar to the nips who these cars are designed for, they also are not designed for 70-80-90mph, stick at 60 and the temps will not go over 80-85, if you tow anything whatsoever, fit an extra tranny cooler in line with the bottom of the rad as they were also not designed for towing.

When flushing remember to disconnect the heater hoses and flush these both ways, the main flaws in these cars are too much plumbing for their own good and a fan that goes around doing sweet FA while having a head made of chocolate on top of a steel gasket and cast block, head almost always goes first. H

[hellmett]

re

I went up the long steep hill that caused the initial overheat again last night and to my relief the aftermarket gauge stayed still at my 'normal' running temp.

So, the renewal of the oil in the viscous fan has helped a GREAT deal!

I can assure you when the coupling is empty/dry then it takes about 75mls of oil to top it up!

My cooling system is as clean as a whistle, I took the whole thing apart about 2 years ago, bought loads of the strongest coolant flush I could get and flushed it back and forward for about 2 days!

I even reamed out the small pipes that run to the back heater matrix with a drill and some bicycle brake cable (BRILLIANT METHOD BTW!).

My rad cap and thermostat are both new.

My coolant now is always clear and there is no residue, it's always like new.

I think my problem is entirely down the radiator, it is basically knackered!

It was reconditioned about 4 years ago but there are pin hole leaks appearing at the top!

As soon as I can afford it I'll stick a new rad in from Roughtrax and I reckon it'll be sorted!

[Hazzo]

"I can assure you when the coupling is empty/dry then it takes about 75mls of oil to top it up!"

I spent ages researching this on every fora/toyo site I could find, general consensus was 35mls, which, once you squeeze in your 50ml bottle seems about right as its so sticky you'd wait forever to get the last drops out, regardless how much you put in I'd rather it had been a belt operated job then you know its working with the revs, obviously once the oil vanishes the fan fks up and your head melts, been there done that, so I'll check/change mine every two years with the coolant, or at the first sign this truck goes over 90 deg. Thanks for the assurances though, H

[frontman]

fan

Cheers for tha guys, I'm just in the process of replacing the head and any cooling ideas are very welcome, I'll check the fan oil tomorrow.
I,ve never had any dealings with auto transmission fluid and wondered how it flows through the rad, ie what percentage of the rad cools the fluid. This must have an effect on the overall rad temp & could I use my disconnected air con rad to cool the fluid, if so can it be too cool ?

[Hazzo]

The oil passes through the rad to regulate the temperature as tranny oil works better at certain temps, under load though it increases the rad temps=not good so its best imo to have an extra inline cooler too, mine came from a scrappy, 20 quid, no problems since and just takes a little longer in winter to get to temperature. Fit a real temperature guage while your there too, the onboard is completely useless.

Lots of opinions on what makes them go too, I dont go with the mileage opinions, I do think this fan is a major contributor due to lack of servicing, my truck was/is serviced every 4 grand, coolant changed every two years. Stat failed on mine, it fails closed, not well thought out but if the fan was operating correctly it should still cool the rad, however the fan just goes round whether it is working properly or not and not being a viscous expert you have no idea as to whether its doing its job (onboard guage), I do now though, it is, and temps never alter by more than 5 degrees with the extra cooler in place.

I'm spending no more time or money on the truck though apart from regular servicing, basically its getting run to ground now and I'll replace the car as and when it regurgitates another big bill, its handy in the winter but thats about it, I don't mess offroad its not my bag but I did need it for towing, I sold the van too so its really surplus to requirements now but I'm suffering no further losses on my outlay. H

[hellmett]

re

Apparently, the 'newer' style rads from Roughtrax/Milners etc. are supposed to be better at cooling the transmission oil as well as the coolant.

Don't know if this is actually the case but the rad sure looks better!

http://www.roughtrax4x4.com/?doc=16&cid=149&vid=528

This radiator is a high quality unit with thick top and bottom tanks that commonly leak with inferior radiators, also features a new high performance 3 row fast flow core to help water circulation.

Once I get me a spare 150 quid I'll order one up and sling it in!

Gary