ATTN F-Wag (another book )
My fan clutch was leaking air. So adding the A/C compressor Y
was the right time to swap in a new fan clutch. You can get parts to rebuild
it for $300.00, then do the deed, new they are like $1200 if you can
find it or a reman. So I found some fan clutches on GL and
picked up the lot. They are made by Bendix. The "More Info"
link on the GL lot clearly said they were for the 14-20 ton
M915 Series of trucks. It is the whole shootin' match, clutch
and mounting bracket. You swap over the 1/8" x 5" long
nipple and 1/4" air feed adaptor and bolt it up. I think I have
4 left for sale btw.
Doing the job alone was a challenge but after contemplating
the situation I found an easy way to do it alone. First remove
the turn signal that keeps trying to give you a prostate exam.
Now simply grab a board, I used a spare M925 Rear cover stanchion.
Now grab a 10" bungie cord. Lay the board over the top
of the "X" bracing up high w/ one end DS and the other end PS.
Lay the 10" bungie perpendicular centered over the FC. Grab
one existing fan belt and put it in the inner groove of the FC.
Connect the 10" bungie to the belt. VIOLA! You just made SOLDIER B
and he will not talk back either! After that you still need to man-handle
a 42 pound chuck of metal in and out but this method makes install and
removal wayyyyy easier.
Ok so I get it all together less the fan shroud and knowing Murphy is out there
I started it to make sure things were ok. I start it and the fan instantly
was locked up and turning. Hmmmm, well, were all smarter then the
instructions for such mundane tasks right? NOT. I pick up the instructions
and it clearly says ;
SYSTEM CHECK OUT
After completing the installation, the fan can be
tested for function by starting the engine with no air
in the system. The fan should operate immediately
after the engine is started and should stop as the air
pressure builds to 80 PSI........
OK so I wait for 80 PSI and the dang thing is still in lock up
100% of the time.
I start to question my fan actuator but I KNOW it worked prior.
Shortening the story
after talking to the awesome owner at KIT MASTERS
and a great email from Larry at fanclutch.com I found out that
The Bendix operates opposite of what the OE Horton does.
(PS, KitMasters now owns the Bendix design!)
The Horton is air to engage, normally closed switch.
The Bendix is air to dis-engage normally open switch.
UGH!!! I am PO'd, I would prefer the truck to be stock and I go inside
and pout. It is now too hot to work, I am done. I called a friend, he does
not answer, he was at the Littlefield Collection auction. He calls me back
several hours later and he knew exactly what was going on and he added
that the Bendix is a better design IE this;
"If you loose your air compressor you loose your fan clutch w/ the OE system.
NO DRIVE HOME (Of course caging brakes) but w/ the BENDIX if you loose
your compressor the fan comes on and you are still OK! " (So if your OK
driving a 28 thousand pound behemoth w/o brakes carry on! ) but still,
something to think about.
I think it makes good sense, I am sticking w/ the Bendix but I do have to
swap out my Thermo-Pneumatic Control Valve. The instruction sheet for the BENDIX has part
numbers right there for the part you need based on a 10 degree closing
over the engines thermostat. I found a 190 degree actuator
cheap on Ebay NOS.
BUTSOMEHOWEVER. I was told that with some Thermo-Pneumatic Control Valves
you can simply swap the air plumbing and it works backwards and I "think" I
was told that if you have a Thermo-Pneumatic Control Valve that works by wires
that you can reverse polarity and it runs backwards too! So it all depends
on what you have as to weather or not you need to change your
Thermo-Pneumatic Control Valve.
Or you may have the BENDIX stock!
...and I just realized I didn't change the innermost serpentine belt and now I will
take it all apart and do it all over again so I will tell you how the method
I suggested prior about leaving the fan attached and just pulling the
FC to replace belts works... sigh, more practice.
DAYCO 5060436 (serpentine belt)
EDIT: The Bendix FC says your Thermo-Pneumatic Control Valve should be 10 degrees higher
than the thermostat. The OE thermostat is supposed to open at 185 degrees I just read, ,
I had assumed 180, bad on me, so to do this perfect per Bendix instructions you want
to buy the Thermo-Pneumatic Control Valve that is set at 195 degrees. I grabbed a
190 degree Thermo-Pneumatic Control Valve, I think I will be A-Ok.