Viscous fan test

[ab56452001]

Hi can anybody tell me how to test my clutch fan please, ive heard of a couple of different versions, 1- that the fan should be hard to turn when cold, 2- the fan should spin around freely when cold ?,cheers.

[carlosprite]

It should bind up, it should not spin freely; there should be resistance.

[rainman]

start it up, get a rolled up news paper.
stick the news paper in the fan, fan should stop, when cold.
when engine is hot and the fan working the fan will not stop, be careful with the news paper. with practice you can actually "just hear it" when the engine is hot and revved.
good luck with it.

[ab56452001]

So when cold no resistance , when hot resistance is that correct = if its hot and stops spinning when i put the paper in, its nackered ?

[rainman]

So when cold no resistance , when hot resistance is that correct = if its hot and stops spinning when i put the paper in, its nackered ?
yes.
when hot is should be locked up solid, bit more then just "resistance" - be careful with the newspaper.

[ab56452001]

ok ill give it a test tomorrow,thanks

[BLU-125]

Or do what I do and buy a new one and keep the old one as a spare! I actually have a few spares, do you want one?

[Cypher]

The biggest difference I noticed between my old completley stuffed one and a new one was noise, before there was no wind noise, just engine noise...now when it's it hot sounds like theres a hurricane under my bonnet.

[kennyboy]

Don't stick a newspaper in it, that's plain stupid. When completely cold you should be able to turn it around five turns an then it should go tight.
If it wobbles at all it's knackered, or if it looks like fluid has leaked out from where the shaft goes into the clutch.

[banky]

Can you explain 5 turns? By that logic it would go tight as soon as you turn over the motor and run constantly.

[ab56452001]

Or do what I do and buy a new one and keep the old one as a spare! I actually have a few spares, do you want one?

Thanks for the offer, but your a long way off , i was past that way just 3 weeks ago !,cheers

[ab56452001]

Hi all, i just did the newspaper test when cold, fan didnt stop just shreded the paper ?

[Cypher]

Let the car warm up till the electric aux fan kicks in, turn off engine, spin clutch fan, if it spins freely its stuffed

When the car is cold all the fluid in the fan clutch settles to the bottom of the unit partially covering the internal drive plates, so it'll seem the fan clutch is engaged when you first start it until the fluid is forced to the outside due to centrifugal force and the clutch spins freely. When the car heats up this heats a bi-metallic coil on the front of the fan clutch which opens a small valve within the clutch, forcing the fluid to pump through the centre of the clutch and thru the internal drive plates thus engaging the clutch.

edit: also sticking stuff into the running fan (stuffed clutch or not) is just a stupid idea...

[ab56452001]

Thanks for that Cypher, well the fan seems o'k' the water pump pumps and the electric fan works , cut the guts out the thermostat and put back in, no change maybe runs even hotter when warmed up !,just takes longer to get there, ill put new thermostat in and just leave it i reckon, it never boils, just that i cant get used to the gauge sitting on around 105 c

[kyphonii]

Really, at running temp there should be a good flow of hot / warm air
They don't lock up solid.
When you start cold they spin up and if you hold the rpm at a steady 2000 the fan will drop back and you will hear and feel the drop back, as the temp increases the fan hub will detect the temp and should firm up as it heats up.
If you have a good flow of air that all you need. check that a towel will be pulled in to the grill at hot idle.

[ab56452001]

Thanks for replies, tried the towel test, and seemed o'k', towel got pulled in slightly at hot idle and really pulled in at 2000rpm !, one thing though, i thought the fan supossed to lock up when hot?, when i turned of engine i could move it easily by hand, not free spin , but nowhere near locked up, i suppose that leaves radiator even though the radiator shop said its been replaced by a brass one some time ago !,cheers.

[kyphonii]

If the fan locked up the noise would be similar to a jet taking off and at 2000 rpm your forward speed is more that the fan could pull in so it's really only for idle, parked and tail winds. slow speed. Then the thermo will kick in.

[carvesdodo]

As kyphonii said ... they dont lock up solid.

Usually when the clutch is "locked up" ... its spinning at about 60-70 percent of engine revs.

For the clutch action to be "locked up" in its various stages ... the little coil spring on the front needs to be sensing an air temp of about, an average 70*c.

The spin test is only indicative ... the towel test is slightly better ... and theres a drawnout process in the factory manual using temp probes and timing lights and stuff ... to get a better indication of the clutch servicability.

FWIW ... if you are unsure of its age or quality ... throw it away and fit a new one that you will feel confident with.

Prices vary dramatically depending on the seller ... but Ive found the one Wooders stocks to be a good allrounder.

As for the radiator ... It may have been replaced "recently" ... but that doesnt mean that there isnt a bunch of junk clogging the lower section.


Whats your actual problem ... high running temp ??? ... overheating ???

[ab56452001]

I just had another look,from what i can see the radiator fins look o'k',but, the a/c condenser in front that covers a lot of the radiator seems to have heaps of bugs and dirt in it, might give it a blast with the pressure washer, hope i dont do any damage !,cheers.

[ab56452001]

As kyphonii said ... they dont lock up solid.

Usually when the clutch is "locked up" ... its spinning at about 60-70 percent of engine revs.

For the clutch action to be "locked up" in its various stages ... the little coil spring on the front needs to be sensing an air temp of about, an average 70*c.

The spin test is only indicative ... the towel test is slightly better ... and theres a drawnout process in the factory manual using temp probes and timing lights and stuff ... to get a better indication of the clutch servicability.

FWIW ... if you are unsure of its age or quality ... throw it away and fit a new one that you will feel confident with.

Prices vary dramatically depending on the seller ... but Ive found the one Wooders stocks to be a good allrounder.

As for the radiator ... It may have been replaced "recently" ... but that doesnt mean that there isnt a bunch of junk clogging the lower section.


Whats your actual problem ... high running temp ??? ... overheating ???

To me the vehicle seems to run to hot 103c to 106c on a 20c day driving in moderate traffic,i think it should be around 95c to 100c,its never cooked and ive towed and done big trips up north of 4000km plus, if it didnt have a bloody gauge i probably wouldn't bother,ta.

[kennyboy]

To me the vehicle seems to run to hot 103c to 106c on a 20c day driving in moderate traffic,i think it should be around 95c to 100c,its never cooked and ive towed and done big trips up north of 4000km plus, if it didnt have a bloody gauge i probably wouldn't bother,ta.

There are two different thermostats commonly in these jeeps, you can get one to run a little cooler but 105 isn't extreme in any case.

[kyphonii]

My system is standard except that the auto doesn't run through the radiator.
A 95 degree thermostat will work in the 95 to 107, will not spend much time below 95 as the thermostat will close. The temp sensor is the coolant temp leaving the engine, so its no biggy up to 110. the temp of the day is not that important, the efficiency of the cooling system is more dependent on the difference in the ambient temp and the radiator core temp, 20 degree air and 110 radiator gives 90 degree diff, lots of potential there, 40 degree day and 95 radiator is only 55 diff, the heat generated by the engine will be no different on a 20 or 40 degree day.
If you system can't drop the temp from 107 to 95 quickly with thermo and high idle then you have issues. On mine I can see the gauge fall as I watch it.