Fan Hub Getting Hot

[Otterby]

Does anyone know if the hub on the engine cooling fan should get hot? It isn't red hot but is definitely hot to the touch. I have filled it with 80W-90, turned it 180 degrees and let the excess drain out of the fill hole. After doing this some still leaked out where the shaft enters the hub. I worry about the hub going out and letting the fan get into my new radiator.

[rotorwrench]

The fan hubs, starting in 1942, have a metal to metal fit inside for bearing surfaces so they like to be filled with lube as required. If the bearing surfaces get badly worn or scored, they will run hotter than normal, even with lube in there. You can usually feel the play in them to some degree. It may be time to take it down and inspect the parts inside. New replacement parts are available from some of the vendors out there.

[Graeme / New Zealand]

I had one years ago make start to make a hell of a noise. The bushing was flogged out and end float was excessive and there was even "side float". I was bloody lucky it never let go into the radiator. Luckily I had a replacement. Lesson learnt, check the lubing regularly and the end float and side play. You will usually find there is a little end float and play but it should not be excessive and it should not be hot like you describe. I would say if the fan is leaking around the shaft the bushing is worn and is not holding any oil, hence the heat generated. If i remember correctly when I disassembled the "stuffed" one all those years ago the shaft had a "corkscrew" knurl in it to move the oil around.

GB

[RalphM]

I had one that I cleaned up and put new gasket in only to have the pully split while running it. The welded on one half the pulley just “ let go”. The hub was fine.
Don’t know what caused it, but I rebuilt another using new internal parts.

[Ian NZ]

I had a fan hub seize up on a my 47 when I was on a trip I wondered what the noise was so I removed it on the side of the road and continued on home. I now keep a spare one for myself.

[1948F-1Pickup]

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Sorry, but those things (stock) are a joke. Only piece I knew I was automatically upgrading when I got my truck.....

[RalphM]

I have a friend just bought one of those, definitely an improvement.

[38bill]

Originally Posted by 1948F-1Pickup

Sorry, but those things (stock) are a joke. Only piece I knew I was automatically upgrading when I got my truck.....

Nice, Who makes it?

[Kurt in NJ]

It's been a long time, perhaps you should look at the lube chart, I think it uses motor oil, perhaps 90 wt is too thick and making heat

[Kube]

Originally Posted by Kurt in NJ

It's been a long time, perhaps you should look at the lube chart, I think it uses motor oil, perhaps 90 wt is too thick and making heat

If I recall correctly, it specifies 20w.

[Kube]

Originally Posted by Otterby

Does anyone know if the hub on the engine cooling fan should get hot? It isn't red hot but is definitely hot to the touch. I have filled it with 80W-90, turned it 180 degrees and let the excess drain out of the fill hole. After doing this some still leaked out where the shaft enters the hub. I worry about the hub going out and letting the fan get into my new radiator.

80w/90 is way too thick. It should have 20w.

If the belt is not slipping, causing excessive friction and heat transfer, then I'd suggest the bearings are on their way out.

[Drbrown]

This is what Vanpelt says about it:

FORD OIL FILLED FAN ASSEMBLY
The 21A Cooling Fan
Downloaded from Vanpelt Sales LLC web site 11/2013 by Drb

Service and How-To Tips for the Oil Filled Fan Assembly

When Ford decided to change the flathead V8 engine fan design for 1942, they developed a design that moved the fan to a mid level location on the motor. It was felt that this provided the maximum air flow through the heart of the radiator, and over the engine itself. The fan design was simple enough, a steel shaft running through a machined casting on a film of oil. The shaft had a slinger-impeller on its forward end, which tossed the lubricant back over the bearing structure where holes in the casting of the spindle bearing allowed the oil to reach the rotating shaft. The fan design worked well enough that Ford used it for a number of years.

The following V8 vehicles used this fan: 1942 to 48 Ford and Mercury Passenger Cars.

If there is one flaw in the fan, it is this. Over many years of service, plus the lack of service knowledge on them, future owners of such vehicles are not aware of the need of lubrication of this component. Owner's manuals are often lost, and the maintenance tips were never passed on to the next owner. This happens whether the engine remained in a stock vehicle or if the motor was removed and installed in a hot rod. So, what happens if the fan is not lubricated ?

Eventually, one of two things will occur. Either the fan shaft runs dry and seizes in its spindle bearing, thus stopping the fan from rotating and burning up the fan belt. Or, in a worst case scenario, the shaft overheats and breaks while the engine is running. This allows the fan and its hub to separate from the
mount, and causing untold damage to the radiator or other engine accessory components.

First make sure that you have this type fan on your flathead V8. They are easily identified by the eight bolts that attach the fan itself to the hub/carrier assembly. The hub is larger in diameter than any other Ford fan mounts, and the mounting bracket attaches to the front side of the generator mounting bracket. The pictures below will easily show what this unit looks like.

Your next step (assuming your fan still spins freely) is to lubricate the hub. With a clean rag, wipe the hub in the area just behind the fan blade. You will see a small straight slotted screw. This is the filler AND the drain plug! Rotate your fan and hub until the filler plug is up (at the 12 o'clock position) and remove the screw. The actual oil capacity of the hub cavity is about 2 ounces. Ford originally recommended regular motor oil, but changed that later to 85-90 weight gear oil....the same stuff used in your transmission. Use a squirt bottle to add the gear oil into the small opening in the hub. Try to measure out at least 2 ounces and add this to the hub. Now, with a rag under the hub, rotate it until the filler opening is down (at the 6 o'clock position). Due to the internal design of the filler plug opening, the correct amount of oil will remain in the hub. The excess oil will drain out into the rag. If no oil comes out, try adding an additional ounce and repeat the procedure. After the filling is completed, rotate the hub back up and replace the filler plug screw. The original screw has a small rubber-like ring under the screw head. You can use a small washer or O ring from a carb kit if you need to replace this sealing ring. The follow up to all this is just as important. Repeat the fill procedure with each engine oil change. You will probably only have to add perhaps an ounce of gear oil at the oil change intervals, but the idea is to slightly overfill the hub and allow the excess to drain out. This will help assure many years of trouble-free operation of the fan assembly. Don't forget to pass this on to the next owner of the vehicle should you sell it in the future.

[estout81]

I'm like Kube, I think 80w/90 is too thick. I took mine apart and cleaned everything and reassembled with 30w nondet. motor oil. It turned so smooth I was stunned! Been working fine for almost 12,000 miles.

[Mac VP]

20w motor oil was the original specification. Somewhere I found a Ford service bulletin that changed the spec to the gear oil......can’t recall if it was 85 or 90 but that’s not a concern. I’m going to try to find the bulletin on that. Of course, it’s always possible that Ford changed their mind about this, or that the individual who typed up the service bulletin got it wrong.