Radiator fan mounting

[calebpalmer86]

I recently had to put a new alternator and belt on my ‘50 Cub. When I put it all back together and cranked the tractor, I was getting sparks from the front of the tractor, but only at high RPMs. I think that the fan is hitting the shroud, which tells me that it is wobbling. What is the best way to ensure that I have the fan/bolt nice and straight when I mount it? Or could this be caused by something else that I’m missing? I’m learning as I go, with the help of this awesome forum.

Thanks in advance
Caleb from Alabama

[Clemsonfor]

Your not Paradoxz are you? With the 86 I assume your born in 86 which I think makes you to old to be him.

[Glen]

Hi,
It sounds like the fan is too high, or too low, and hitting the shroud, if the Cub has a shroud, it is supposed to have a shroud.
Don't run the engine until it is repaired so the fan doesn't hit anything.
Look in with a light, and turn the engine slowly with the fan, and see where it is hitting.
Be sure the ignition switch is Off when turning the engine.
Or use a hand crank, if you have one.

The fan belt on a Cub should be the right length, so the alignment of the generator belt up and down works right also.
The new fan belts I buy at Case IH make the fan shaft a little less than half way up the slot that holds the fan hub.
They don't use the bottom part of the slot except to slide the fan hub down, to loosen or remove the belt.
Don't put on too short a fan belt, I have seen on here that it creates alignment problems with the generator belt, or alternator belt, when the fan is too low.
Or, don't put on a fan belt that is too long either.

When you are there at the fan is a good time to oil the fan hub, if you didn't.
Be sure to fill the fan hub to the right level. The hub has a lubrication system in it.
Below is a page from the 1949 Cub operator's manual with fan hub lubing info.
The hub uses light motor oil.

http://farmallcub.com/rudi_cub/www.clea ... age-28.jpg

The oil screw has a rubber seal on it, be careful to not lose it. Sometimes it comes out with the screw, and sometimes it is stuck on the hub.
Just thread the screw through the rubber if the rubber is stuck on the hub.
I use a pump oil can to pump oil into the fan hub.
You can give the hub a partial oil change, when you fill the hub like the manual says, before draining the excess oil out, put in the screw, and turn the engine over 10 or 20 times, then drain the excess oil out. That will probably mix the new oil and the old oil some.

Look as the engine is slowly turning over, and see if the front of the fan blades are all running straight.
One or more could be bent ahead, or back, and could be hitting something.

The fan shaft has a thick washer that goes in front of the mounting slot. It is needed to align the fan belt with the drive pulley.
Only the nut goes behind, or in the slot.

Below is a pic from TM Tractor, showing the washer.

[Gary Dotson]

Grab one blade, of the fan, and see if you can wobble it on it's shaft, there should be minimal movement. If you get significant movement, you'll have to replace the fan assembly.

[calebpalmer86]

Clemsonfor, I am not Paradoxz. The fan does have a shroud, which is what I suspect that it is hitting. The problem is that it only hits at high RPMs, so I cannot turn it slowly to look for what it is hitting. I just replaced the alternator belt when I put my new alternator on, but I did not replace the fan belt. I will loosen it up and ensure that the thick washer is pressed all the way against the slot that the shaft mounts inside, then try tightening and running at higher RPMs to see if it clears. I will also check for play in the fan while mounted that could indicate that the whole unit needs to be replaced.

Thanks so much
Caleb

[Jim Becker]

. . . The problem is that it only hits at high RPMs, so I cannot turn it slowly to look for what it is hitting. . . .

Look at all the places where the fan comes very close to the shroud. There should be a shiny spot, or at least a roughed up edge wherever it has been hitting.

[John *.?-!.* cub owner]

As the fan speeds up the blades tend to get just a fraction onger form stretching, and bend forward just a little. Both movements are very small, so as Jim said, you will need to look for places where paint, or rust depending on cosmetics has been disturbed. It will be a very small spot that is already close to fan. Since I believe you said you saw sparks, it will be the shroud or a bolt, since the radiator and it's fins are softer material such as copper and aluminum, so very unlikely to make sparks. Does your fan have the spacer (thick washer) that goes between the fan and mounting bracket?

[Crimson Tim]

You don’t mention noise of something hitting, which I think I would be as noticeable as sparks. Certainly a point of physical interference should become clear pretty quickly. But you do say that this is a new alternator.

Just to throw an alternate idea out there: could the alternator either be bad or wired in wrong in a way to produce sparks when it is up to speed?

What alternator did you install?
What happens when you spin an alternator the wrong direction?

[Nelson 634]

If nothing else works use a timing light to stop the motion of the fan or at least slow it down so you can visually inspect it. Timing light is a strobe light although not variable it may turnout to be close enough to let you see.

Hook it up as you would to time tractor but point it towards the fan blade. It may stop the motion visually or at least slow it down. Safety Note: KEEP YOUR HANDS AWAY FROM THE FAN AND THE SHROUD.

[John *.?-!.* cub owner]

As Crimson Tim mentioned, are you sure the sparks are from the fan? Maybe from the alternator?

[Jim Becker]

If there are sparks, you should be able to follow them back to the source.

An alternator doesn't care which way it turns. The fans on an alternator come in right and left rotation.