Is this Wiki section correct? Cooling Issues

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DanTheDoc
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Post Fri Mar 02, 2012 10:12 am

Hi,

I have a question about the Wiki, it states the following:

If your car starts overheating, especially in traffic, the viscous coupling is usually to blame. For that, we have a basic test:

To test the viscous coupling, you need a cold engine. Start the engine, and then gently try to stop the fan blades turning with a loosely rolled up newspaper. When the engine is cold you should be able to easily stop the fan. If it shreds the newspaper when run from cold your viscous coupling is broken, and needs replacing.

This may be a question with a really simple answer but surely the test above shows that the fan is constantly engaged which would result in over-cooling not overheating as the first sentance states?

Thanks

:?
Last edited by DanTheDoc on Fri Mar 02, 2012 12:43 pm, edited 1 time in total.
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mr_dink
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Post Fri Mar 02, 2012 10:33 am

Quite right!

The way they normally fail is that they don't lock up at all, i.e. you can stop the fan easily with a newspaper when hot.

Never heard of one being locked all the time but I'm sure someone has!
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DanTheDoc
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Post Fri Mar 02, 2012 11:36 am

So am I right in thinking that the best way to test this would be to try stopping the fan when cold (using the newspaper) and then try again with the engine very hot. If the fan stops with the same resistance (i.e. little) when hot, then the coupling is more than likely buggered?
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daimlerman
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Post Fri Mar 02, 2012 11:51 am

DanTheDoc wrote:So am I right in thinking that the best way to test this would be to try stopping the fan when cold (using the newspaper) and then try again with the engine very hot. If the fan stops with the same resistance (i.e. little) when hot, then the coupling is more than likely buggered?
Absolutely correct!

When the fan engages,usually when the gauge is between the upper white mark and the red sector,a distinctive change in sound will be noticed.The cooling fan has little,if any,effect at road speeds above 30ish mph,so if the engine is running consistantly hot whilst being driven,start looking suspisiously at the radiator,the tiny tubes clog over time and reduce it's ability to transfer heat.
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Grrrmachine
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Post Fri Mar 02, 2012 12:19 pm

:o: Nothing to see here, move along...
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DanTheDoc
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Post Fri Mar 02, 2012 12:42 pm

mr_dink wrote:Never heard of one being locked all the time but I'm sure someone has!
HI!!! I've just tested mine with some paper (luckily not fingers) with the engine stone cold and the fan kept spinning producing a sound something similar to a garden strimmer!! New coupling for me.

I think my overheating issue was possibly lack of water :o:

Put a litre in yesterday then opened up today after a drive and it gurgled at me, empty. So in went another litre, sits ok now even after running. I've got a slight leak at one of my transmission connections which I can live with for now but I really should check the water level more often!!

One more question, how can I tell if my radiator cap is the old style one that had the recall by BMW?
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