Viscous Fan diagnosis?

["steve.weighell" <steve.weighell@xxxxxxxxxxxx>]

How do you check the viscous fan coupling (on a 87 520i).  It is the
ordinary, mechanical type.  I had read somewhere that you need to get the
engine hotter than normal, stop the engine and see if you can spin the fan
by hand.  If you can, then the coupling is no good.  Is this right?

I thought I had found the reason for my overheating engine (see earlier post
a few days ago), but I have changed the viscous fan with one I found in a
scrap yard, and this doesn't seem to have worked.   When hot, this fan also
spins freely.  Are they both u/s?  Or is this not a valid way of checking
the coupling?

Steve,
Darlington, UK

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