Viscous fans

[Dman2]

Is there any way to test a viscous fans
Tractor running hot

 

[Vernon]

Unplug it so it runs all the time and see if tractor cools down.

 

[Dman2]

Unplug it so it runs all the time and see if tractor cools down.

Unplug what

 

[wuddy]

Not very scientific but fan should be much harder to turn by hand when tractor is hot so see if there is much difference between hot and cold

 

[sparkey]

When tractor is cold spin fan by hand
heat area , fan housing with a hot air gun
then try and spin fan again when hot, should be harder to turn when hot

 

[Pheasant Surprise]

Rolled up newspaper test; with engine properly warmed up and running at tick over if you can stop the fan with a few sheets of rolled up newspaper then the viscous clutch on the fan has gone.

 

[milkloss]

Why does a viscous fan run hard at startup? I would run for a couple of minutes first for the cold comparison.

 

[Mursal]

You should have a good draw through the radiators when hot.
Some can be locked with a bolt, but you should notice a change in noise from the fan with engine ticking over.

Engine hot, ignition switched on, should be hard to turn fan, as mentioned above.

 

[TripleSix]

Why does a viscous fan run hard at startup? I would run for a couple of minutes first for the cold comparison.

It's to do with the silicone fluid being redistributed around the unit.

Sinks to the bottom when stopped.


The fact it locks at startup isn't an indication it'll lock when hot.

The valving unit may be stuck.


My old Hilux had a viscous fan problem, it wasn't locking when hot, but the valve wasn't seized so I opened it and dumped in a little pot of RC car silicone shock oil.

Sorted....

 

[Cowabunga]

Unplug what

An increasing number of applications over the last 15 years have been using engine ECU controlled Vistronic units. These are controlled electronically and can have varying degrees of engagement, rather than a simple bi-mettalic strip at the front which senses the heat removed from coolant and is either on or off.

 

[TripleSix]

I'm pretty sure NH TM's had an electronically controlled fan...

I used to drive a JD8345 and that had a really fancy fan connected to the hydraulic system.

Shame it started leaking.

 

[Pheasant Surprise]

My old Hilux had a viscous fan problem, it wasn't locking when hot, but the valve wasn't seized so I opened it and dumped in a little pot of RC car silicone shock oil.

Sorted....

Like this?

 

[f0ster]

with viscous fans there is a bi-metal strip right at the centre or it might be a bi-metal coil that curls up more when heated, both types operate a pin right at the centre, this pin can go stiff or seize, see if it can be moved or turned slightly, spray lube on it. but be careful it is set to open a port at the correct temp coming through the rad, when they are working correctly they draw when started from cold, after a few mins they turn freely, then above the preset temp that draw again,

 

[Dman2]

Have bolted them up before
Ran one for years with 4 bolts in, never a problem
Think this is the issue here, gradually gets warmer, although does cool down rapidly when load taken off

 

[Mursal]

Well if it'll take a bolt, you can then test and work from there

 

[f0ster]

If you are in a hard water area the rad might be blocked inside with lime scale

 

[f0ster]

it will use a bit more fuel with the fan locked in,

 

[Lincsman]

I'm pretty sure NH TM's had an electronically controlled fan...

.

They do, i thought they might be less reliable, but has turned out not to be the case.

 

[roscoe erf]

Is there any way to test a viscous fans
Tractor running hot

hot air gun

 

[Flat 10]

Tie it up (carefully) to see if that cures the problem.