Thermo-viscous Fan operation - Carlton - BobbyDazzler
Hi everyone

When I bought my Vauxhall Carlton 2L CDX (private) a few weeks ago I noticed during the inspection that one of the blades on the thermo-viscous fan was missing (probably caused by the previous owners attempts to remove the very large and awkward shroud that projects from the rear of the radiator).

However, when checking the condition of the spare wheel I noticed a second hand replacement fan nestled in there with it.

I replaced the fan at my first opportunity (i.e. when I had located two large enough spanners in the skip that purports to be my garage) but kicked myself for not inspecting the replacement more closely. There were two rods welded across the large rotating nut and onto the backing plate. The effect of this means that the fan will not ‘free wheel’, but will spin at a rate exactly that of the shaft.

I went ahead and fitted it reasoning that more efficient cooling was better than less efficient cooling. Especially in this weather.

I think I have the rudimentary understanding of thermo-viscous fans in that they operate on a kind of silicon (?) clutch effect i.e. when enough heat is present the silicon stiffens or solidifies so that the ‘take up’ of the fan corresponds more closely to that of the engine speed and when less heat is present they ‘free wheel’ thereby creating less of a cooling effect.

When running the car the gauge returns a temperature reading that hovers just above the first quarter mark. It rises to about the halfway mark on steep hills (and there are lots of those around here!). This is just a little cooler than what I had previously observed. There are no ‘Normal’, ‘Hot’ or other indicators on the gauge.

Is the correct operation of this fan vitally important?

Thanks for any advice.

Regards to all
Thermo-viscous Fan operation - Carlton - SpamCan61 {P}
First quarter to half way sounds like normal operating temperature range for a Carlton to me; I'd only start to worry about it if it doesn't get to first quarter in very cold weather.
Thermo-viscous Fan operation - Carlton - Peter D
Has the car got a tow bar. I ask this because some caravaners modify the fan to run continuously to account for the extray towing load. The permanently coupled fan is noisier and increase the cold weather warm up time thus the cold wear and the mpg I would change the fan for a normal one.

Regards Peter
Thermo-viscous Fan operation - Carlton - Dave N
Not sure how warm up time is affected, as no water runs through the radiator until the thermostat open anyway, so it should be irrelevant.

However, be careful, as the fans aren't rated at full engine speed, so can blow apart at maximim revs.
Thermo-viscous Fan operation - Carlton - sean
Believe it, or not, running your fan constantly will waste 2 to 3mpg.

That's why the expensive viscous coupling is fitted.
Thermo-viscous Fan operation - Carlton - BobbyDazzler
Hmmm....thanks very much everyone.

Anyone have any idea how much a new fan is? (don't think a breaker would be a good bet)

many regards
Thermo-viscous Fan operation - Carlton - rileyrm
I bought a new fan 3 years ago for about £120 at main dealer,my fan was seized and ran at same rate as pulley. The blade noise was very loud,worse than the diff noise. I may be wrong but I believe the main allen bolt may be reverse theaded.
Thermo-viscous Fan operation - Carlton - BobbyDazzler
Phew....breaker starting to look like a good bet!

The fan's not at all noisy btw

Thermo-viscous Fan operation - Carlton - Dynamic Dave
Try either Dixon\'s or Autovaux to see what sort of price you\'re looking at to replace it.
Thermo-viscous Fan operation - Carlton - none
A seized viscous coupled fan is likely to disintegrate at high engine revs. The bigger the fan, the more likely it is to fly apart. Extra load is placed on bearings and drive belts. The fan flexes more than it's designed to, and is likely to touch parts that it shouldn't. Relace it.
Thermo-viscous Fan operation - Carlton - Cliff Pope
If you need a new coupling anyway, why not get an electric fan?
(Breakers, Kenlowe, etc)
Saves mpg, quieter, fan belts last much longer.
Thermo-viscous Fan operation - Carlton - BobbyDazzler
Hi all

Thought i'd update.

Managed to grind off the welded pins on the complete fan (no broken blade), took out the viscous coupling of the damaged fan and checked operation....warmed with hairdryer and it stiffens nicely....put the two together and hey presto! complete fan with no broken blades and working viscous coupling :)

Thnaks to all for your help and advice

Best regards
Thermo-viscous Fan operation - Carlton - Peter D
Hi Dave N, the increased warm up time is caused by the fan inducing unnecessary cold air and blowing it over the engine. In addition, even with the stat closed water stil circulates arounfd the block and some through the radiator this is to avoid the stat opening and stone cold water being pumped into a cold block and cracking it. Hope that clarifies your thinking. Regards Peter

Value my car