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jwhitton

Viscous coupling - is it "bleeding"?

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Posted (edited)

Defender 90 300Tdi

While performing some other work, I removed the fan and viscous coupling assembly.

I put the assembly on a box with the bolt threads facing downwards. A few days later when I re-attached the fan and coupling, there was what looks like thin silicone grease / vaseline on the box, and appears to have "bled" from the viscous coupling. The thick fluid is clear and has no smell.

Just wanting confirmation this is so, and probably assume I need a new viscous coupling?

Edited by jwhitton

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Never heard of one leaking, but have been told to store upright to prevent the viscous fluid moving to one side.

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Thanks, yes don't store on the thread side horizontally. I don't think its making much noise, so will run it longer to see how it gets on.

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My experience of fan viscous couplings is that if they leak in service the blades get a film of dirt, which wipes off easily by finger pressure, so is easily checked.
As the leak becomes more extreme a line of dirt appears on the underside of the bonnet, above the fan; unless the fan is inside a cowl, when it's the inside of the cowl that becomes covered in greasy dirt.

I now regard all fan VCs as service items. The service interval may be 'long', but it's an item that falls into the catagory of  'check and replace if required'.
I now feel that If it gets to the stage of being mechanically noisey the the check interval has been much, much, too large.
My first did that, and started my learning process. Subsequent examples, on different vehicles, taught me about 'greasy dirt clues', as well as lack of cooling becoming noticable.

Regards

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Thanks David, it now appears the leak has stopped once the fan is installed and back in the vertical position.

I will continue to monitor as suggested.

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