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Old 02-27-2017, 06:45 PM   #1
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Fan Clutch

hey all,

i broke it.

i was re-assembling everything and i thought i had it all together right, so i tried starting the engine.

as quick as i turned the key, i broke the fan clutch connection. i thought the rubber piece bolted to the clutch on one side and the bracket on the other. but when i tried, it ripped the rubber out and the wire connections.

I'm not finding a picture of how it connects in the service manual, if anyone would describe it or take a picture of theirs.....
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Old 02-28-2017, 08:12 AM   #2
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That rubber piece holds an electro magnetic coil that will activate or deactivate the clutch in a similar fashion as an modern ac compressor clutch. There's bearings in there as well that will seize up and cause what you just had occur. Not sure if that's what you did or if you damaged it in some way causing it to drag. But, that need to come off and be replaced. I usually remove the radiator/intercooler and get at it from the front, same way I do the belts. But you can try your hand at it from the back.
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Old 02-28-2017, 10:40 AM   #3
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does that piece have a name - block-o-rubber?

thanks for your help! i haven't seen the piece of rubber in any fan clutches pictures. or on quickserve.

idk now if i had those wires hooked up when i tried to start the motor or not, if they were, then the clutch should have been activated when i tried to start it.

the clutch was working fine before i changed the belt. i was concerned that little piece of rubber wouldn't hold, but it failed immediately making me think i lost an insert or something in the rubber piece.


thanks again for your help!!!!!!
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Old 02-28-2017, 11:00 AM   #4
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You might not find it on quickserve. I'll have to try and remember the brand (just replaced one a few months ago, seized bearings) You'll have to go through bluebird or find a part number off of it. The Rubber serves as an isolator/vibration absorberer for the magnet coil.

The clutch shouldn't have been activated upon startup unless you have a toggle switch to do so manually.

Either way, that still shouldn't have spun even with it activated, That coil free floats on the shaft, so either the bearing seized, or the thing was damaged causing it to grab the coil and tear the rubber/mount.
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Old 02-28-2017, 11:08 AM   #5
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if its an electric clutch its likely a Horton, the factory used hortons on alot of these.. the EC450 was a common one that does not use hydraulic fluid and does not use air..

sometimes they were retro-fitted onto Busses after the fact for better performance typically over what a viscous clutch could do..
-Christopher
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Old 02-28-2017, 11:17 AM   #6
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That's it Chris. I kept thinking hayden but knew that wasnt correct. As far as numbers I couldn't tell you. I call the dealer and they usually send me what I need.

Btw turf, your fan looks goofy in the picture to me for some reason. Like it's not seated on the hub right. Maybe it's just the angle of the camera but it's something I would check.
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Old 02-28-2017, 12:27 PM   #7
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thanks, i will check the fan too. the picture rotated when i uploaded it, so its upside down. it does look odd.

i called Arkansas Valley Diesel, and got the part ordered in just a few minutes. its a good shop!
they sent the picture from bluebird. its part #9. ordered and on the way.

when i said "isolation absorber" i sounded smart. thanks. better than block o rubber.

this one rotated too....sorry
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Old 03-05-2017, 09:23 AM   #8
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1 more question about fan clutches.

do the wires matter? is there a polarity to it? in the damage i did, i stripped off the connectors. one wire heads to a nearby temperature sensor and then the other one disappears into a harness. the wires appear as 4 different colors. i am color blind and this kind of problem gives me trouble.

i hooked it up yesterday and got the truck up to operating temp. not hot enough for the fan clutch to kick on. no smoke yet!


here is a pic of the wires coming out of the fan clutch. idk what color they are.


tia
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Old 03-05-2017, 09:33 AM   #9
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Chances are there is a plus and minus, im not sure in your case.. if its simply an electromagnetic clutch then as long as neither of the terminals have continuity to ground you shoiuld be Ok.. if its hydraulic and a solenoid is involed then polarity is important..

my *GUESS* is that the wire going into the harness will measure +12 volts any time the key is on..

and that the temperature switch likely has either 1 wire, or its second wire goes to a ground someplace...

the theory being that when the sensor gets hot, its internal switch grounds the connected wire, giving you +12 at the clutch.. im not up on those clutches enough to know if they are polarity sensitive.. if they are then id expect it to be marked someplace..
-Christopher
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Old 03-06-2017, 09:20 AM   #10
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The polarity is most likely speced(like most engineered things) but it's not important because of it being a simple magnetic coil. Like chris said, the wire from the harness is 12v with key on and the other goes to a switch which grounds internally at 205*F or there abouts.

That's only if this is a mechanical engine.

Electronic will have the fan controlled by the computer.
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