Fan Tapered Hub Damage - help with cause and repair

[Diastole]

To anyone with advice,

I changed my water pump the night before a parade d/t a leak. Installed my working, relativity new, cast aluminum two-blade fan. The taper on my backup water pump was such I needed to add a washer behind the castellated nut to seat the fan and nut correctly.
The fan and water pump worked great for the 12 mile highway driving to the parade, and all thru the parade. But on the way home, a terrible screeching, rattling, grinding noise came from what sounded like the front of the engine.
On inspection, there was aluminum powder on the back side of the fan hub, see picture. The fan had a little sideways movement, <1/8", but turned with the engine.
The engine ran well. The water pump has sealed front and rear bearings and has been lightly used. The belt was appropriately tight with 1/2"-3/4" deflection. No cooling problems.
The tear-down inspection of the fan and water pump revealed the water pump is in good condition. Both bearings solid and without significant runout or wear, see pictures. The shaft is centered without runout.
The taper on front of the water pump shaft has a GREAT DEAL of new scoring, gouging, grooves, and wear, see pictures. When I removed the fan the woodruff key was lying on the bearing, I am unsure if I knocked it out, or if it had been dislodged prior to my disassembly, see photo. It appears that the tapered shaft to fan hub is the source of the horrible sound.
Tried to replace the fan on the tapered shaft and there is too much wear, slop, and movement. It appears to this novice that the woodruff key somehow came out and the fan and shaft rotated without the key.

See pictures

The tapered hub of the fan is shot. Any ideas how to fix it, where can I get a new hub to press in? I do not want to buy a new fan - hub assembly.

Do any of the FordBarn Experts have any other explanations for the problem? Remember the water pump is perfectly normal, except no paint on front end due to the wobbling fan scratching it off.

Thanks in advance,
Diastole in the Smokies

[Gary WA]

Did you have the keyway in there? 1/2 moon and cotter key

[Diastole]

Yes the woodruff key was used, but may not have been seated correctly or was too small, or its groove was too deep.

[Benson]

See attachment of instructions to install fan from the manufacturer.


This MAY explain some other reasons why your fan was damaged.

You most likely will need to replace damaged fan and make the checks listed in sheet while installing new fan.

I would buy fan from a trusted parts house. Many times the fans you buy from ebay or the trunk of some one's car are defective and seller trying to get rid of them.

Some parts have only one source, others have more than one source, some good , some not so good.

The Ebay seller may not even know that the parts he has are defective.

As an example: Berts Model A Center knows which parts are good and sells the known good parts.

Berts uses these parts daily in their repair shop and in rebuilding original Engines and building The New Burtz Blocks and they know which ones are good.

www.Modelastore.com


Below is installation instruction sheet from manufacture of the fans.


A-8600-A TWO BLADE CAST ALUMINUM FAN
MOUNTING INSTRUCTIONS

It is very important that you test fit and rotate your fan before installing it with the castle nut. Slide the fan into position on your water pump and rotate the fan by hand to see if the ID of the fan hub is rubbing anywhere. On a new fan, this will be obvious by the scuffing of the paint. If you feel any drag or rubbing, you will need to file or sand the snout of the water pump wherever the high spot is. High spots are caused by irregularities in the casting, castings being bored off center, or castings that are slightly larger in diameter than normal.

Why do you have this problem with a new aluminum fan but not an old steel fan? A casting requires more material thickness than a stamping in the hub area. If these fans were made with the bore as large as a stamped fan, there would be little to no material left to support the edges of the belt pulley. The result would be the edges of the belt pulley braking off very easily.

Install the key in your water pump shaft and slide the fan into position. You should feel the fan bottom out on the taper of the shaft. If this does not happen, your fan shaft may not have been cut deep enough for the key to set in the proper position. If you have this problem, first check to be sure the key is seated all the way into the groove of the shaft. If it is in all the way and you still experience this problem, file the top of the key down slightly so there is no interference when the fan is slid into position.

If the water pump is off of your car, put the fan in position, hold the pump in a vertical position and lightly drop the pump on the impeller end to seat the fan tightly on the taper. It is best to drop it on a firm surface such as an anvil or a concrete floor. Now you can tighten the castle nut and insert the cotter pin.

Note: The depth of the taper does vary on shafts. If you find that you can not get the nut to go down far enough to get the cotter pin in place, dress the back of your castle nut down with a file or belt sander until the proper depth can be achieved.

[jrelliott]

The instructions I received with my aluminum fan reminded me to seat the fan blade snuggly to the water pump shaft before installing the castellated nut. If the fan hit the casting of the water pump suggested removing material from the casting. You could try one of the axle shaft bushings between the fan and the water pump shaft. It is a farmer fix and may work.

[nkaminar]

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New fan, new key, follow instructions. The key was not installed correctly. It cannot come out on its own because it is captured by the grove on the shaft.

[Dave in Petaluma]

Picture #6 shows that the woodruff key may have been installed backwards, with the curved portion engaging the slot in the fan hub.

[gdmn852]

Hello, on the new aluminum fans , as mentioned, they are thicker at inner hub area , I have found that it was necessary to remove some material from the water pump so that the fan could spin freely, as the water pump was a repro also, it was machined slightly off center of casting. Aluminum would have a tendency to expand when warm so good idea to road test and check for clearance.

[JayJay]

I've had some experience with this issue, see https://www.fordbarn.com/forum/showthread.php?t=343910 post #16. Your photos look to me like the fan was installed, bottomed out on the snout of the water pump when the nut was tightened, but this wasn't noticed. As the fan turned and wore internally it now was not a snug fit on the water pump shaft, started wobbling and this is what you ended up with.