New aluminum fan blade problem

[rivcokid]

Hi all - I waited at least 6 months for the new aluminum fan blades to appear. I got mine and we just went out this morning to put on in my 31 roadster. Guess what? It doesn't fit. We put the new blade on the water pump housing (sealed bearings so a leakless one) and couldn't get it on far enough. Took out the calipers and the ID on the original steel fan blade is 1.79 inches, whereas the new aluminum one measures 1.68. There's also about the same difference depth wise too. In short, the castle nut will go on but barely, we can't get a cotter pin in, and when we do tighten the castle nut, the entire pump and fan blade will not move. Naturally, this happened Saturday morning of a 3-day weekend, so calling Snyders is out until Tuesday.

Has anyone else run into this? I'm wondering if the fan blade housing has to be thicker due to the nature of aluminum. BTW - I have no way of machining this thing myself.

Thanks for any ideas as usual!

[Neil Mylar LakewoodCA]

I had the same problem, but managed to get part of a carter pin to work.

[Hitman]

Check to make sure the woodruff key is seated into the shaft and fits the groove in the fan hub. Do you have another pump or shaft to double check the fit?

[rivcokid]

@Hitman - we made sure. All appeared to be ok. Unfortunately I don't have another pump/shaft.

[Joe K]

There has been a lot of "variety" (being generous here) with the taper that pump shafts have been made with.

Vince Falter on his Fordgarage site describes a fan shaft taper with TWO intersecting tapers - the quality assurance is that bad.

And fans have suffered from a similar issue. Many earlier aluminum fans and even perhaps some modern aluminum production have a taper "cast" in place - and no assurance that the taper is Ford design or even uniform. On some of these you can see the "flash marks" of the segment mold piece used to form the taper.

As in NOT MACHINED. Just sent out in an "as cast" condition.

Hence the advice from many to mount your fan, torque it up to the torque limit for the size/thread of the pump nose nut. Then run it for 500 miles. Then DO IT AGAIN.

What you're doing is "stretching" the taper female over the taper male by deforming the fan hub.

Check your new fan for evidence the taper has not been machined. It is reason to reject this as a replacement part.

Also check Vince's page. https://www.fordgarage.com/pages/waterpumpshafts.htm There are several page links there worth seeing, including a page which shows the 1-1/2 inch per foot taper design drawing for the pump shaft.

Joe K

[SwampLedge]

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Did you get the installation instructions? https://www.snydersantiqueauto.com/c...INUM%20FAN.pdf

[Joe K]

1-1/2 inch per foot taper reamers exist and are commonly used with ball joint (front end) installation. It creates a nearly "self-locking" taper. I say nearly as unlike a morse taper (5/8" per foot) 1-1/2 inch/foot is "more removable."




Holding your fan perpendicular to the axis of cut will be the challenge. My 20" Flather lathe (1873) comes to mind.


Joe K

[philosofriend]

A few weeks ago our club was helping a member put his engine back together. We, like you, found that the brand new fan blade would not fit over the water pump housing. We tried it on another known good water pump and found the same thing. It wasn't the taper making the problem. It was the cylindrical big hole at the rear of the fan that was too small to go over the water pump nose.

[Richard Knight]

As written by the O.P. the I.D. of the pump hub is binding on the cast iron nose of the pump. As pointed out by swamp ledge there are clear instructions. It is not just the fan I.D.,the O.D.of the pump nose is often larger than the original pumps. The solution is simple, grind away the offending cast iron. After that I think you will find the fan will go on the taper just fine.

[gdmn852]

Hello, being a casting as opposed to the original stamping, the Id is smaller than originally made. It’s common to have to grind down the water pump casting for clearance between the pump and pulley area .

[JayJay]

I have run into this problem on the last four water pumps I’ve handled. Oversized nose, and often the shaft is not centered in the nose of the casting. I created a jig that I mount the water pump to in my small lathe. I turn the nose of the water pump down to 1.640” and everything fits fine. Richard Knight nailed it - remove material from the nose of the pump housing.

[Bob C]

After you get the fan to fit on the pump without the key I lap the fan to the shaft with valve grinding compound and check the fit with prussian blue.

[Y-Blockhead]

It states in the first paragraph instructions from Snyder's to check for clearance and remove material from the water pump as needed. This is due to the aluminum fan/pulley being thicker than the sheet metal original shaft.

I have not had an issue with the taper.

https://www.snydersantiqueauto.com/c...INUM%20FAN.pdf

[bobbader]

YES to grinding the nose of the water pump housing. That's the problem.

NO, NO, NO to the reamer. With all respect to Joe K ............... yes such a reamer IS available. But, any tapered reamer can cause worse problems if they cut past the point of making a "perfect fit" between the tapered hole and the tapered shaft. In my opinion, in this case, using a tapered reamer in an already cut tapered hole most likely will make matters worse.

[rivcokid]

Thanks everyone. I'll work on trying to remove a bit from the water pump housing.

[1crosscut]

Use a paint pen, chalk or similar to paint the inside of the fan, mount it and turn the fan to transfer the paint to the body of the water pump to better show where the interference is.

[wrndln]

I had the same problem with the inside of the aluminum pulley being too small some time back. You shouldn't need to ground down the original waterpump housing (like GDMN852 mentioned above) if the company that made the fan made it right. Why oh why can't suppliers make parts correctly.

[CT Jack]

Do what Richard Knight recommends. Based on your measurement you need to remove a minimum of 1/16'" of the pump surface material within the nose area of the casting. I had to do this several times in the past. The first time it happened I took material off the ID of the fan casting. That was a bad idea, it destroyed the fan. Ford used many vendors to produce pump castings. It appears the external dimensions around the pump nose were not closely specified.
Remove the pump and grind or belt sand the nose area. Without the shaft key installed test fit the fan on the shaft for clearance. A clearance >1/16" should be achieved.

[Keith True]

Years ago when people were complaining about this a couple of us sat down with my pile of pumps.At that time I had 20-25 of them.NO TWO measured the same at that interference point.Most of them still had shafts in them,and most of them had enough clearance for the fan.Some didn't,but it wasn't by much.The few we did determine to be true originals were OK.But,after 90 years of replacement parts it would take a fine points guy to decide on most of them.The correctness of the water pumps has never been an issue for me.It is for others,and a couple of guys have pawed through my pile of them to find the correct one for their application.

[Richard Knight]

A further comment. The modern leakless pumps often have a larger diameter to the cast nose of the pump due to the ball bearing installed in that location. As mentioned by Kieth often the casting is not concentric with the shaft. Some folks fail to see the big picture. With 5 million As produced and at one time countless producers of spare parts I can imagine maybe 20 million pumps being produced or more. Anyone who thinks they are all the same is not being realistic. Grinding the cast iron nose has been going on since the cast aluminum fans became available. It is a small price to pay versus having to buy a new radiator, hood, or having an unexpected lobotomy.