[TR] more on fans

[Jim Muller]

Two more thoughts on fans.  When I bought my Spitfire it had been 
through some curious times.  A PO had found it susceptible to 
overheating so her favorite LBC shop had cleaned out the radiator, 
replaced it, flushed the block, added a manual fan switch, maybe even 
dropped the car off a cliff for all I know, and finally swapped the 
engine.  It still overhet repeatedly.  Finally they discovered that 
the Lucas fan just wasn't spinning very well.  It appeared to turn on 
and no one had noticed that it spun more slowly than it should've.  A 
new motor solved the problem.  But by then she had sold the car to 
the guy I bought it from.

The second point is that my first Fiat, a '69 124 Spider, had a fan 
coupled by an electromagnetic clutch.  WHen the temp sensor read high 
enough it would engage the clutch by feeding current to the fan 
through a brush similar to the brushes in a generator.  I had trouble 
with it only once.  The cause, I discovered, was the brush dangling 
by its spring from its holder.  Never figured out how it came out, 
maybe from a bonehead mechanic's error.  Once I re-mounted the brush 
the temp went back to being well-behaved.  I've never sesen another 
fan clutch like that, but it certainly worked.  I suppose a plain 
electric motor is simpler.

Jim Muller
jimmuller at rcn.com



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