Another Original 2-Blade Fan Takes Its Toll

[BRENT in 10-uh-C]

I wish Marco would chime in here and give his opinion.


One thing that I can say with regard to "after all the points" is this, ...plans are at this moment that there will be 5 cars in fine-point judging at French Lick this summer that have been restored at my shop. In each case, ALL of their owners have made conscience decisions where they feel they are satisfied with losing points for the sake of financial prudence. I would imagine other folks have navigated through the same 'waters' with regard to this and made like decisions. Knowing what I know about it from their perspective, all of them have different goals for which direction they went and each of those decisions have a vast amount of merit.

To me, the issue that needs to be resolved first is "why" they break. I recently heard a story about a mechanic who instructed his apprentice to repair something on a car. After a few hours, the apprentice returned to the instructor and stated "It's all fixed now!" The instructor asked the young man did you determine what caused the item to break? The apprentice shook his head and said No. At that point, the instructor explain to the apprentice, then you really didn't fix the problem did you. THAT is kinda my attitude. Making a new fan that looks authentic is awesome but if there is still concern about the new one breaking too, then maybe they problem has not been determined & solved.

[MikeK]

Originally Posted by BRENT in 10-uh-C

Well, in all true honestly, I ain't a metalurgist nor do I profess to know anything regarding what you say about the cyclic work hardening so I will yield to your knowledge in that regard, however one or two thoughts do come to mind.
Since we mentioned mufflers earlier in this thread, we'll bring that analogy up again. We can buy the cheapie muffler for less than a $100, --or we can buy a steel Aries for about double the price of the cheapie. One could make an argument that both are made of steel and are 'expendible items' so why bother with paying twice as much for the Aries?

To me, the same mindset could be applied to discussions about shocks, or tires, or piston rings, or patch panels, ...or many other things. I guess it really boils down to perceived value.

I realize that $200-$300 for a fan seems like a lot of money, but in today's society of manufacturing, I don't think less than $100 will be enough to cover Design, Tooling, R&D, and all the R.O.I. Would you not agree that probably 1000 units is a realistic market for these for the life of the tooling?

.

Yes Brent, perceived value. I have no issue no mater what the new fan costs- $1 or $1,000. I simply won't use it at any price point because it doesn't provide the one thing that would be a plus for me- increased reliability vs. a stock fan.

To me, in a fine point car an original fan is 100% reliable and I would see no benefit from any replacement fan. Why? Realistically, a car in fine-point is a low hour, slow speed car and will not see accumulated hours of fast highway touring. Has anybody ever had an excellent original fan break in fine point during judging or on the mandatory tour? Despite all the broken fan horror stories, there are still plenty of excellent originals, I have a few of both the early and late design. Sure, a pitted, cracked, welded, ground, bondo filled fan painted to look new is a bomb, but does anybody laying out the bucks for fine-point really do that? Then maybe the new fan fits their perception of value.

If you do intend to regularly tour with a car, then I see either an excellent original or the new steel fan as equally suspect in long term reliability, and both unacceptable to me. Same basic design and materials = same failure mode. For touring you need a different fan, IMHO.

Perceived value. To my eye, those lousy aluminum repops stick out like a sore thumb with their thick edges, and are not the answer either, at any price point. One can spot it a mile away. It REALLY gets me when I see one of those aluminum trying-to-fool-you fans, and then follow the fan belt around to an alternator! Whats the point? In my mind, you get more respect just running a plastic fan rather than trying to fool almost nobody with the aluminum propeller. If you replace the original fan for increased reliability, I just don't see a new steel propeller fan as any better for someone who will do a lot of driving.

Cyclic work hardening - C'mon Brent, you do know what that is. Flex a fender at the bead a gazillion times on bumpy roads and it cracks. Or flex a fan blade by varying the load on it every time engine speed changes. Eventually, Crack!

[Terry, NJ]

I've never been clear on this. My Town sedan has a four blade steel fan. Is it OK?
Regards, Terry

[Mitch//pa]

how are the aftermarket 4 blade bolt together fans as far as reliability

[Richard/Ca]

I would buy one if the price was right. I just like the looks of a two blade fan. Even though I also had one come apart on me.Luckly it just put a hole in the hood.

[MikeK]

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Originally Posted by peters180a/170b

The guy i am talking about with a "NEW STEEL" authentic fan did test one out. And yes its 10X stronger and runs at a higher rpm's. He even flew down to Texas to speak to Miller welding company about the welds.

"And yes its 10X stronger..." Great! Show me the independent engineering test reports that prove a sampling of several of the new fans are 10x stronger than an equal sampling of NOS fans. An unsubstantiated claim like that is a BIG RED FLAG to avoid this product. Because some experts say so is meaningless.

"...did test one out" ONE??? Statistically, a sampling of n=1 is invalid. Tested for how many thousand running hours, and at what varing speeds approximating engine speed and temperature cycles? The fact that it can do a very high sustained speed imposes no cyclic loading, no matter how many hours you run it. Useless data to me.

[JoeWay]

Originally Posted by MikeK

...Despite all the broken fan horror stories, there are still plenty of excellent originals...

Mike, how do you propose the restorer identify an "excellent original" fan?

The guy whose fan started this thread has been restoring Model As, and collecting parts, for over 45 years. He is very selective and conservative. I have seen him cut defective parts in two, or otherwise render them unusable, to make sure they would never end up in use on a car.

He picked an apparently good fan. He cleaned it to bare metal, found no visible flaws, then had it wet-Magnafluxed by a qualified shop. It was certified crack-free...yet it failed in about 1400 miles of medium-speed touring. No pits, no cracks, no welds, no grinding, no bondo--yet it failed.

What else should he have done? What else would you do? My feeling is that one CANNOT be positive that an original welded fan is good. They are all subject to catastrophic failure at a moment's notice. Failure is certainly more likely on a motor that is operated at higher rpm, but can happen at any time on any motor.

Joe

[MikeK]

Joe, I agree with you 100%. There is nothing you can do beyond inspection that shows a part to be sound, either used or new.

Mean time between failure is just an average on any part. It applied to the original fans, and it applies to replacements. I'm not convinced that a brand new one will fare any better. The first new one could last a hundred years and a million miles, the second new one a year and 1000 miles. Both may have x-rayed perfect. MTBF would then be 50 years and 500,500 miles. That doesn't help the guy who bought the second one. If it is identical to the original part, it will have an identical failure profile.

It took Henry 3 years on the first design to realize there was a problem, if that's what the new fan is like there will be some % of failures fairly soon. After 4 years, Ford gave up on the design, including the later '31 fan design. B's had no welds.

Would I buy one, even if they are $300? Yea, before I'd buy a $50 aluminum one, if convenience was the issue and I didn't want a visible replacement. I may buy one anyway, just because it will fit into my repop collection.

[skip]

OK where do I sign up for a stamped steel fan?
Too good to be true. We should have some confidence that a new stamped steel fan is 'a stout fellow'. How about a test till failure? Spin it till it don't come home.

Oh reminds me the space shuttle. A turbine bladed fuel pump needed a scatter shield around it 'just in case'. So the engineers spun her up with a blanket around it till it came apart. Not only did it go through the blanket, the lab, the wall but out into the parking lot.
The turbine flys tomarrow with no blanket around it. An acceptable risk since the pump runs far below failure data.

skip.

[skip]

Hartzell Fan inc Piqua Ohio. Hummmmm
They make aeroplane propellers and industrial fans.
They have the engineering.
And test lab
And know how
They just need to assess the need
That would be all of us
Can they make a buck on it

skip.

[Midwest Tin]

Hi, What are your thoughts on the Late 31 fan blade. Has anyone had any trouble with running a late 31 fan blade? Jim

[skip]

"blade tip speed is slower and out of the harmonics area"
Brent may have something here.
Let me preface my remarks...I have no knowledge as to why the cast [not stamped?] two blade fans fracture at the hub.
Bare in mind the the fan and water pump impeller spin 1-1/2 times the engine rpm.
The engine is good for 2600 rpm so the fan spins 3900 rpm at times.
Good point blades don't fracture at the tip. I doubt if it's harmonics but more like stress.

What causes stress? I can't hear anything 'whining', snapping like a bull whip [that's hyper sonic compression of air], or whomping air like a propeller and no thumping. Hummmmm says the boy.
~Vibration? Out of balance and shaking. Should feel the vibes by touching the water pump shaft. Or listening to the whirl with a long handled screwdriver to the ear.

~Bending? More like...

~Flexing toward radiator while pulling air? Straightening out when slowed. Back and forth till she breaks. So rpm's climbing and backing back down kill engines...why not fans? Could cause the root of the blade to flex and start to fracture.
You know...I wonder what a guy could see with a variable flash zeon strobe light.
Freeze the moving blade.
Might be able to detect flex.
The fan works hard at moving air.
Resistance through air squares as speed doubles.
Your hand out the window at 25 mph vs at 60 mph. Speed flips the hand right up.

Air has weight. 1.087 lb per one cubic foot at 70 deg F. Less weight when hot, but the same one cubic foot volume.
One cubic foot is two cubic foot at 600 deg F. But weighs the same as one cubic foot at 70 deg F. [standard air]
Engine hp used to turn the fan moving hot air decreases.
If the fan was driven by an electric motor the cold start motor amp would drop as the air through the fan heated. New York Blower manual on the four standard Fan laws explain this.
I think I read that the fan moves 220 cubic foot a minute at X? rpm.
That's about 240 lb of air a minute.
If anyone wants to play with the 'draft-through-the-radiator' divide the 220 cuft by the sq foot opening of the radiator. Just for poops and grins. That air heated to about 160 deg F gives the approximate btu cooling so 220 cfm x 1.087 weight of air x [160 deg F -70 deg F air; rise in deg F] = 21,522 btu per hour. [btu's are always in hours] Fun?

~Pulling like centrifugal forces. I don't see it. The blade will fling but that's after it fractures. That's the result. Not the cause.

~After 80 years, I think the hub/blade root just get worn out. The problem is the new replacement fans are sometimes of bad metallurgy, materials/process, and craftsmanship.

~I have heard that a cast fan that has been cleaned and vapor blasted with glass beads then degassed at a high temperature, then cooled and powder coated gloss black and cured at a lower temperature will show the crack developing. HIGH GLOSS thermo-set epoxy polyester cured powder paint is brittle and will show cracks if the blade flex's at the hub. An early warning? I don't know. Speed kills. A four blade fan doesn't move more air 'cause the blades have less pitch I hear but they make noise as Bruce says. Weigh more too.

When I wash my BMW 320iS and it's ideling away, the electric cooling fan kick's on and the car moves foward about 1/3 of an inch. Is that cool or what?

That's my 2 cents.

skip.

[JoeWay]

Originally Posted by skip;6769...[COLOR=blue

why the cast [not stamped?] two blade fans fracture at the hub...[/COLOR]

Skip, just so we're clear, the fans in question are weldments made up of several steel stampings. No castings involved.

Most or all of your points likely apply to the situation.

Joe

[Marco Tahtaras]

Originally Posted by Midwest Tin

Hi, What are your thoughts on the Late 31 fan blade. Has anyone had any trouble with running a late 31 fan blade? Jim

This type of fan was simply an alternate design (supplied by Holley I believe). It was used concurrently with the Ford design and was not chronological replacement.

I haven't studied that later fan closely but it appears to be essentially the same design in the hub area. The biggest advantage to the Holley design is there is no place for internal corrosion in the main blade area as it's a single thickness. This DOES provide one major benefit. The Ford design fans typically (probably 95%+) have substantial internal corrosion between the layers. If you look closely at one you will see the outer 2-3" of one or both blades bulged and distorted. This causes imbalance among other problems.

That single issue seems to provide the later type fan with a significantly reduced failure rate. However some still fail. The other issue that contributes to failure is bent/distorted fan blades. This is NOT obvious with a purely visible inspection. The problem with these unique looking propeller fans is that the neatly shaped fan blade make a very comfortable HANDLE! Over the years (or decades) most fans have been used to turn (or attempt to turn) the engine over when trying to zero in on the timing mark with the pin. I can't believe the number of times I've seen this done! How much can these fan blades take before the blades become distorted? Of course it will not occur with the two blades evenly. Besides the undesired stress placed on the blades at the hub, this creates a functional imbalance between the blades. Yep, MORE problems!

All these problems can be identified with proper inspections but I only know of 3-4 people that have ever done so. A decent machinist will measure crankshaft journals to see if they are round and/or tapered, or measure ring gaps before assembly. However they will likely look over a fan closely, say "gee, that looks good" and assume it is! Magnafluxing wont mean a thing except to tell you if you need to have your eyeglass prescription updated!

One thing I find very interesting is the number of folks that claim "there was no crack there this morning but but the blade just went!" I've seen MANY (abused) fans on swap meet tables over the years with a crack measuring 1/8"-1/4" long. Funny, the fan blade is still attached. How can that be if they fly right off when the crack begins? Hmmm, I'll have to figure that one out.

With all that said I won't recommend anyone else run an original fan. I don't want to be called to task for the decisions of others and the resulting success or failure. It also won't hurt my feelings to have more fans to choose from on the swap meet tables!

As a final note, I had a friend that I helped complete the restoration on his '30 Deluxe Roadster in 1975. He put the original fan back on the car at that time. Before he died he had put about 90k miles on top of the 70k miles already on the car. Yep, about 160k miles on the fan! He drove the car across the USA as well as many "short" trips of 1500+/- miles each way and he DID NOT have an overdrive! Yes, I'm sure that fan will eventually fail but when? 200k miles? 250k? I have no idea.

[Deluxe Delivery Don]

i need to purchase a fan in the few weeks so what would any of you guys buy that is on the market right now? It is an all stock sept 30 deluxe delivery. I don't want to have any of the same problems as of the above post . Thanks for any help.

[Tom Wesenberg]

I would buy any GOOD original fan. I have a few for my own cars. I check the pitch, check the plane they run in, and check to be sure the leading edge of each blade is parallel to each other. When this criteria is met, then I balance the fan and use it on my car. I feel safe with it, but still check it for cracks when I think of it.

I think the 2 blade aluminum is a good second choice if I can buy it in person to be sure the leading edge of the blades is parallel. If I could buy one with good parallel blades I would then refinish it to the smoothness it should have, then I'd make sure the tapper was correct to fit the shaft snuggly, then I'd balance it and use it. I know the aluminum fans are advertised to be balanced, but I haven't found any to be as close as I like them to be balanced.

[Mikeinnj]

Let me understand this.....the original Model A Ford fans are known for cracking and turning into shrapnel and now someone want's to duplicate, manufacture and sell the same fan ??? How would the pricy new repro fan not end up cracking and failing like the original ones did ?

[JoeWay]

I don't think either (any?) of the potential manufacturers plan to duplicate the original fan.

They plan to make a fan that is visually identical. That leaves lots of room for modern technology and materials.

Joe

[JoeWay]

Originally Posted by Marco Tahtaras

...Magnafluxing wont mean a thing except to tell you if you need to have your eyeglass prescription updated!

...As a final note, I had a friend that I helped complete the restoration on his '30 Deluxe Roadster in 1975. He put the original fan back on the car at that time. Before he died he had put about 90k miles on top of the 70k miles already on the car.

I usually hang on your every word, Marco, but I don't understand your eyeglass prescription analogy--nor your apparent disdain for Magnaflux, which is a proven method of detecting cracks that are otherwise invisible.

And as MikeK mentions above, a sample size of one is worthless. I would add that anecdotal evidence is also pretty much without value. I'm not willing to put my radiator, my hood, and perhap even my physical well-being on the line on the off chance that I might have a fan that won't break.

These fans are a proven hazard. I've destroyed two that already had cracks, and given away one that had been carefully and thoroughly cleaned, inspected and Magnafluxed. If I still had any, you'd be welcome to them. In fact, I can probably get that one back if you want it. I'll pay shipping.

Joe

[Mike V. Florida]

Originally Posted by Mitch//pa

mike was it the replacement bolt together 4 blade fan

Yes, It was on the car since the '80's. Many thousands of miles but the problem was still mine. I failed to check the fan for a few months and it bit me in the butt. I could see the old break and the new.