[V8] viscous fan removal

[dsaad at icehouse.net]

First off the electric fan:

These things are EXPENSIVE! I believe it is worth your time to rebuild the
electric fan. I lost mine because the front bearing ( a $5 part) seized up and
burned up the brush holder board. The brushes and holder board match those from
a fan motor used on Chevy pickups so a good electric motor shop should be able
to replace the brushes and bearings cheap.

Once the motor is in top shape you need to verify it works on all three speeds.
The dashboard diagnostics are handy for this, as is the resistor jump out trick.
This is documented in the manual.

The viscous clutch is a little harder to diagnose. With the engine temp over
100C the clutch should be engaged. If you rev the motor you should feel and hear
that the fan is forcefully pushing lots of air. This is the primary cooling
system for the motor - I believe the electric motor is MOSTLY for increasing the
efficiency of the AC, with a side benefit of cooling the motor at idle speeds.
If you hear grinding noises or don't feel good air movement you may need a new
clutch.
Remember it is a left hand thread, and not easy to get off. I think the nut is
32mm - but would not swear to it.

I made a "pin wrench" out of a really heavy "L" shelf bracket (maybe 8" per side
or so and 3/16" thick) and two round head wood screws. Here is a little "ascii
art" to try to describe it:

\o  o/
 \  /
  \/
  /\

Just cut the bracket in half and drill a hole in each upper inside corner as
shown. The wood screws should have a smooth shank about 3/16" in diameter (this
is the part that fits into the holes on the fan pulley) between the head and the
threaded part about 3/4" long. The hole you drill needs to be just a hair
smaller than the screw shank so you have to hammer the screw into the hole for a
nice press fit. Next hacksaw off the wood screws so there is about 1/2" of shank
left. Arrange the two pieces as shown and loosly bolt together in a V. Thats it.

I got a cheapo 32mm open end wrench and I think I had to grind the head thinner
so it would fit. Also cheap and easy.

Of course you could weld or build this a million different ways, but this way is
easy and cheap and anyone can do it in their garage.
It makes a very sturdy tool that also has worked on my other cars.

Dave


Quoting Charles Wurts <cwurts12 at mindspring.com>:

> I think I need to attack the fan clutch, but am not absolutely certain.
>   May I ask how one can tell for sure?  My fan is working, but am
> suspect of the speed.  Is an educated guess grounds for replacement?  I
> know I am not getting all three speeds on the electric fan, but my
> temps are getting past 100 already in stop and go traffic on warmer
> days.  The radiator is only 2 years old, as is the Tstat.  Tis the
> season to study the cooling system....
>
>
> On May 4, 2005, at 2:28 PM, Dustin Carter wrote:
>
> > Hi all,
> >
> > What’s the trick to removing the viscous fan?  No matter how much
> > force I apply, I can’t seem to get that nut to break free.  I thought
> > maybe I was turning it the wrong way, but changing directions didn’t
> > make a bit of difference.  Any ideas?
> >
> > Thanks,
> > Dustin
> >
> > --
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