Viscouse fan replacement question?????

[gillsl500]

Right guys after speaking to Rav on here i carried out a simple check to see if my viscouse fan was working properly.

Where by I folded a news paper and held it to the fan while it was turning, I was expecting the paper to be ripped to shredds however instead the fan just stopped under the pressure of the paper. The car was at temperature but was wondering if the car had been cold, would the fan have been operating at it's normal functional speed?

Ok so my main question???

1) what part of the viscouse fan do I need to replace? I mean the fan it's self appears to be solid so I'm guessing the mechanism that drives it should be replaced? Or does it all come in one complete kit where you replace that mechanism and fan it's self?

Any ideas of how difficult this particular job might be?

Many thanks [/list]

[Rav335uk]

No, fan is not part of the viscous when bought new.
There are a number of bolts holding the fan on the viscous.
You need a 32mm slim spanner, and undo the large nut the opposite way as it has a reverse thread.

[BenHar]

The fan will only shred the paper if the temperature is starting to get high.

At normal temperature the viscous clutch will not "engage".

Ben

[aimlessrock]

Replacement is a doodle, invest in a viscous spanner from your local motor factors..crank the bolt ( note Rav's remarks. As to the thread).. Buy a replacement unit, bolt the fan to the coupling and re-attach..easy does it

[gillsl500]

Cheers for the help guys

Benhar might just have a pOint?? So if the fan only kicks in when the car is over heating? Because if that's the case my car had only been running for about 8mins or so, at this point would the fan have kicked in, the temp guage was half way?

Actually come to think of it at the same time I was attempting to bleed the coolant system? So that being said would the car have even over heated correctly with the coolant being released through the bleed nipple?

So how long should I leave my car in order to bring the car to optimum temperature?

Also guys can you please list for me all the reasons why a car would over heat? Or is it just the viscouse fan that would cause this?

Just so we're clear on when and how the car over heated, on a couple of occasions the car was stationary with the engine started the temp guage went upto 75% full, then when I ran the car at speed the temp guage normalised, how ever I must state that there was no coolant in the car when this happened, so would this combined have caused the car to over heat or will it just be a viscouse fan problem?

Cheers

[Rtaylor2208]

After you refilled and bled the coolant system are you still losing coolant? Also have you checked for mayo in the oil under the filler cap.

The main reasons for overheating are:

1. An Air Lock
2. Failed or failing viscous fan
3. Stuck closed thermostat
4. Failed or failing head gasket (i.e. mayo in the oil)
5. Blocked Radiator
6. failed or failing water pump.

[BenHar]

Just so we're clear on when and how the car over heated, on a couple of occasions the car was stationary with the engine started the temp guage went upto 75% full, then when I ran the car at speed the temp guage normalised,

This does point to the viscous fan failing.

If the temperature goes back to normal when moving it implies that the cooling system is working when air flows over the radiator.

Ben

[gillsl500]

RTaylor, cheers mate. I've checked the filler cap and luckily no Mayo mate? I still need to check the thermostat though?

Cheers Ben, but I have one more question? What triggers the viscouse fan to go on in the first place? Is it a sensor?

How shall I get the viscouse fan to kick in properly, as it would to normalise the temp?

Cheers

[gillsl500]

RTaylor and also after checking the coolant level there been no coolant lost, but i haven't driven her since re filling the coolant! Cheers

[Morat]

The clutch mechanism in the fan responds to temperature. It gets thicker as it heats up and forces the fan to spin. Because there is still some friction when the clutch is cold, the fan tends to spin a bit anyway, but this isn't enough to cause proper cooling airflow through the rad - just enough to mask the fact that the fan isn't spinning properly when the engine is hot! Hence the newspaper test to see if the clutch has locked up fully.

The system is quite simple and elegant, also it is very reliable as long as you change the viscous clutch every 15 years or so

[BenHar]

Cheers Ben, but I have one more question? What triggers the viscouse fan to go on in the first place? Is it a sensor?

It is filled with a liquid that gets thicker as the temperature rises.

Something like that. There is no switch/sensor.

Ben

[Rav335uk]

Have you managed to get the heaters blowing hot air yet?

[Morat]

^^ Very good question!

[gillsl500]

No heat yet guys, but I haven't been able to check the thermostat yet? Will try and do that tmrw?

[Brianmoooore]

Cheers Ben, but I have one more question? What triggers the viscouse fan to go on in the first place? Is it a sensor?

It is filled with a liquid that gets thicker as the temperature rises.

Something like that. There is no switch/sensor.

Ben

The 'sensor' is a bimetallic strip that you can see across the centre of the hub. It pushes a pin right in the middle of the hub.

[BenHar]

The 'sensor' is a bimetallic strip that you can see across the centre of the hub. It pushes a pin right in the middle of the hub.

Thanks, Brian. What does the pin do? Is there fluid involved? Or did I imagine that too?

Ben

[Brianmoooore]

http://www.daviescraig.com.au/Fan_Clutc ... ntent.aspx

[BenHar]

http://www.daviescraig.com.au/Fan_Clutc ... ntent.aspx

From that: "As your engine heats up, the thermal spring on the front of the clutch expands, which opens a valve allowing the silicon fluid to drive your clutch at an increased RPM"

I can understand that maybe centripetal force pushes the fluid out when the valve opens but what makes it go back as the engine cools?

Ben

[BenHar]

Found a better explanation here: http://neuralfibre.com/paul/4wd/tuning- ... fan-clutch

Ben

[Jetl3on]

Hallo Gills,

Sorry to hijack your thread, how did you get on, I have the exact same problem, except trouble arrived in threes.
First the battery went dead, so I jump started, then whilst idling it overheated within 20mins and coolant spilled out.
Switched off the engine quickly, let it cool then started again, this time the lights on the dash came on, ABS, Battery and a circle with an exclamation mark.

Bleed air from system
refilled coolant
manually checked fan
checked battery terminals and earth
No Mayo in coolant or rocker cover.
The FAN did not kick in when it got hot, which it normally does.

Now its idling nicely, temp just under 50% with no sign of overheating, plus the warning lights are out.
But im worried, symptoms from what others have said it Sounds like the FAN, but initially it got hot very quickly. Is there a way to eliminate the Thermostat or Water Pump, how do you check?

cheers