4 blade fan

[mrwarm]

anyone running one?. pro and cons.

[BRENT in 10-uh-C]

Pros & Cons, ...it used to be that 2-blade fans were dangerous before reproduction fans came on the market. 4-blade fans were introduced by Ford for AA applications where air was needed to cool the radiator at slow mph speeds. Tests have shown that a 4-blade will set up a wall of air in a passenger car that actually slows down the frontal flow of air when driving over about 30 mph. Use a 4-blade if you don't have a repro 2-blade fan, --or if you are only driving at slow speeds with a marginal radiator.

[WHN]

My recommendation, use a new two blade fan with engine side pans. If you have a good radiator and grease less water pump, your good to go. There is a reason Ford did things.

[Growley bear]

I have seen some repro two blade fans with as much as 7/32 run out in the blade tips. Before installing one check the run out and balance.
A four blade fan also causes much more work if the water pump needs to be removed.

[BILL WILLIAMSON]

If your fan is tight, NO cracks, has done a good job, Then RUN IT!
Bill Simple

[Growley bear]

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Fans need to be inspected on a regular basis. If your fan has no sign of stress cracks and is tracking properly then if it is not asked to spin faster than Ford intended there should be no reason to worry.

[WHN]

About thirty years ago we had a fan blade break off at 45 mph. The damage it did would cover the cost of many new, high quality, correct reproduction blades. Prior to breaking, it showed no signs of having a problem. Like cracked tires, an 88 year old plus two blade fan is an accident waiting to happen. I treat our Model A like our daily drivers. Safety first or don't take it out.

[Patrick L.]

I've been running a 4 blade for a long time. I installed it because I had it hanging around and noticed a crack in the original 2 blade. Purchased a new 2 blade a while back but haven't gotten around to install it yet. The 4 blade works just fine for me and as far as I know they don't have a history of breakage. Maybe this year it'll get changed, maybe.

[Charlie Stephens]

The four blade fan was introduced in 1933 and carried part number 46-8600. It was continued into 1934. It was the dealers replacement fan for 1928-1934 four cylinder cars (see the Green Bible and/or http://www.fordgarage.com/pages/model46fans.htm) and that is the reason there are so many around. They too have been known to throw a blade. I think this was problem because people used the fan blades to turn the engine over when working on it. Once they were bent and straightened there would frequently be a stress riser and it would eventually grow until the fan blade failed. It is the fan that I always use but if starting from scratch I would buy one of the 2 blade, cast, aluminum fans. I would not buy one second hand (unless I knew the seller) since a lot of them had problems. I would buy from a company with a good reputation and if it had a problem return it.

Charlie Stephens

[duke36]

The repro 2 blades are lightweight and nicely balanced though some may have better finishes than others.

[BILL WILLIAMSON]

An EXPERINCED mechanic knows how to turn an engine a FEW degrees, with the fan blade, without DAMAGING it! SOME just don't ADMIT IT--LOL
Bill Trick

[Patrick L.]

My old worn 1961 engine [ that doesn't leak or burn anything] with 45# compression can be turned [ with sparklers removed] with just a tug on the belt.

I do have to admit that I certainly have turned engines by grabbing the fan. But as Bill points out, there is a way to do it and a few ways not to do it. [ smiley face]

[CWPASADENA]

I run Ford 4 blade fans on my cars.

I inspect them every so often.

DO NOT use a fan that has rust pits or has been damaged or straightened.

I WOULD NOT run a repo 4 Blade fan. Most are poorly designed and made and the blades will flex and fatigue.

The repo 2 blade fans seem to work well but some of our club members have had trouble with them becoming loose on the shaft. Either they were not tightened properly or the taper in the fan was not correctly machined.

As stated before, I would NOT buy a used aluminum fan. Some of the early ones were not machined correctly.

The original Ford 2 blade fans are for display only. They will rust between the 2 layers and crack and brake.

Again, JUST MY OPINION.

Chris W.

[28Ca8149]

I wasn't aware that they gave trouble .My AR still has it's two blade fan 174958 miles later

[daveymc29]

When a four blade becomes a three blade, bad things will occur. A friend had the errant blade go through the hood, Straight up, well almost. It got only one panel. I was lucky with my two blade when it flew apart, it just ate up the radiator core and grabbed the light wiring.Many of our members have horror stories with both two and four blade fans. The new two blade from the reputable dealers is the best. At road speeds they don't interfere with the air flow and at slow speeds they are adequate for the cars, perhaps not so much for a truck hauling grain out in the field, but not many doing that these days,

[CarlG]

After my 4 blade fan's rivets let loose and took out my perfectly good radiator, I opted to go with a plastic fan.

[KenCoupe]

I have been using a 4 blade fan since I bought the car about 13 years ago. I have not had any problems with it (yet). I have recently heard more and more stories about them losing blades similar to the original 2 blade fans. I don't want to take a chance with that, so I have bought a new repro 2 blade aluminum fan. I just need to install it.

[Growley bear]

The aftermarket 2 blade fans that I have HAD experience with were out of track at the tips, poorly balanced, powder coated inside the tapered hole, and would work loose in a short amount of time. Were they balanced? If so how with blades out of track, poor fit on the shaft, and gobs of powder coat that ran down the length of the blade before curing?
My experience with these has not been good and even though they may now be better, my past experience tells me to leave them on the parts shelf.
Things that spin need frequent and close inspection. I check the oil in my Model A at least once daily before I start the engine. While I'm at it I employ my 2 foot rule. Everything within 2 feet of the dip stick is given an inspection. Ask anyone who has had experience maintaining helicopters. Centrifugal force even on small automotive fans exerts a tremendous load on the blade especially at the root area. I have turned engines over with the fan for al least 55 years without an issue.
It is also hard for me to believe that a fan with absolutely no issues all of a sudden exploded.
Just my opinion backed with experience.

[Barry B./ Ma.]

I had a late 31 design fan start to crack at the inner junction where the 2 layers come together to 1 layer. I replaced it with an aftermarket balanced cast aluminum and it ran true and gave no problems.

[TinCup]

One need only see an 80+ year old fan go through the top or the side of a hood once to have a better understanding of metal fatigue. 80 dollars is pretty cheap these days for a cast aluminum 2 bladed fan.

[BirchRidge]

My 4 blade fan decided to give up this morning.. I revved the car at the carb when it happened, I'm glad it took the radiator and not my head

[BirchRidge]

[IMG][/IMG]

[Fred K-OR]

I installed 4 blade fans on both of my rigs. This was before I saw all the discussion on the Barn about them. So far so good but do check them once in awhile like it looks like you should do on any fan.

[denniskliesen]

My original 2 blade fan wasn't consistent in shape on the blades. One blade had a hole in it near the end. One blade looked puffy from what is inside that might have been rust swelling. I didn't feel comfortable with it so I bought a new 2 blade from a local vendor. Installed it and measured blade tip distance from the radiator for each blade. good fit and finish. A little over $50 for peace of mind.

[Tom Wesenberg]

Originally Posted by BirchRidge

My 4 blade fan decided to give up this morning.. I revved the car at the carb when it happened, I'm glad it took the radiator and not my head

Using a 4L fan belt instead of the correct 5L allows the belt to ride low in the groove, which will speed up the fan speed. Also the unbroken blade looks misshapen, so I wouldn't trust it. Buy a new aluminum fan and the correct belt.

[Tom Endy]

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I would never run an original Ford two blade on a Model A. They are 85 plus years old. Moisture has likely gotten into the hollow area and has rusted from the inside. They are prone to cracking from fatigue and if they come apart they are likely to lodge in the hood, the radiator, or your forehead.

Most of the new aluminum two-blade fans on the market are of good quality. The ones I have purchased from Bratton's worked well. I have a static balancer I check them on. They can easily be balanced by taking metal off one blade.

A while back there were some on the market that were not machined properly. Most vendors have discarded these by now. Best not to buy a used one. There are also repo water pump castings around that are oversize and will bind in the fan.

When installing one make sure that it seats on the taper properly and it rotates without obstruction. Make sure you install a steel flat washer under the nut to prevent galling into the aluminum and offering a false torque.

Tom Endy

[George Miller]

I agree with Tom. That blade is bent up not worth the chance. A fan is always bending as it speeds up and slows down. If you ever bent metal back and forth it will break from fatigue. Get a new fan they are good quality now days.

[Chris Haynes]

My A has the Ford 4 blade fan on it. Yesterday I idled for miles in the Santa Clarita 4th of July parade. It was a hot day in the mid 90's. The engine temperature never rose out of the operating range. I do have an aftermarket fan shroud on it.

[BirchRidge]

Originally Posted by Tom Wesenberg

Using a 4L fan belt instead of the correct 5L allows the belt to ride low in the groove, which will speed up the fan speed. Also the unbroken blade looks misshapen, so I wouldn't trust it. Buy a new aluminum fan and the correct belt.

the blades was not misshaped until one decided to go south, it must have happened att the same time I put the engine in three days ago and ispected the fan when I mounted the water pump and didn't see any cracks or dents.
I will change the belt and fan but first i have to find a new radiator

[Synchro909]

Chris raises a good question. He has an aftermarket shroud on his car. I have nothing on any of my As, shroud or splash pans and have little or no overheating problems. The only time any of mine will get too hot is when pulling the camper at 50mph in O/D in ambient temperatures in the mid 90s F. I don't think a shroud or pans would help at cruising speed but I can see that they might help at sustained LOW speed (I can't remember the last time I did that anyway). I have only ever seen one Model A with a shroud and never any pans and cars were like that for decades.
So here's the ? How important are shrouds and pans for every day use?

[Lona]

A year or so ago, I discovered a cracked two blade fan on my roadster. I searched several vendors at the time for two blade aluminum fans but all were back ordered. So, I ordered a plastic four blade fan to use until the two blade alum fans were back in stock. After reading all the nightmare stories about broken fans of all types, I decided to leave the plastic one on. I can deal with flying plastic but not metal, thank you.

Glen

[ursus]

I have to wonder why nobody has come up with a plastic two-blade fan attached to a metal pulley that has the appearance of the original fan? The plastic blades could pull sufficient air at lower speeds but flex for lessened drag at high speed and, being plastic, will be less likely to cause injury or damage if one takes flight. Is this a crazy idea, or what?

[steve s]

THis happened to a friend.

[Charlie Stephens]

Originally Posted by steve s

THis happened to a friend.

I would like to point out that the fan shown is an aftermarket reproduction fan and not the one most people are referring to (Ford part 46-8600).

Charlie Stephens

[denniskliesen]

Charlie, So the fan in your picture is a Ford fan? And the fan in steve s is a aftermarket fan?

[Charlie Stephens]

Originally Posted by denniskliesen

Charlie, So the fan in your picture is a Ford fan? And the fan in steve s is a aftermarket fan?

Yes. My fan is the one that came out in 1933 for the Ford 4 cylinder engines and it was the dealer replacement fan for 1928-34 for many years (the is why there are so many of them).

Charlie Stephens

[Big hammer]

What is it with fords and fans ? I had a 1978 Mercury that lost a blade, could not find any trace of where it came off. Because it wasn't a ford it wasn't on the recall, and had to wait several weeks for ford to make one. 8 months later ford did send me a check for the purchase price. I haven't heard of other makes having fan problems?

[Mike V. Florida]

Originally Posted by Patrick L.

I've been running a 4 blade for a long time. I installed it because I had it hanging around and noticed a crack in the original 2 blade. Purchased a new 2 blade a while back but haven't gotten around to install it yet. The 4 blade works just fine for me and as far as I know they don't have a history of breakage. Maybe this year it'll get changed, maybe.

I did the same thing and the 4 blade shed a blade destroyed the radiator and the vibration from 3 blades took out the water pump. Your car your choice.

[daveymc29]

Two blade aluminum. No vibration and no cracks. Have also used plastic five blade, never saw plastic four blade.

[denniskliesen]

I noticed a plastic fan is much smaller in diameter. Are they all like that?

[al's28/33]

Here's my question.....

Since the FORD replacement fan 46-8600 was also issued for the '33-34 Model "C" four cylinder cars and there are soooooo may of them around using their original fans, why are "A"s so susceptible to blades breaking off ?????

Is it because Model "A" drivers push their cars to current speed limits and treat 86 year old vehicles like modern cars ?????

[Mike V. Florida]

Originally Posted by al's28/33

Here's my question.....

Since the FORD replacement fan 46-8600 was also issued for the '33-34 Model "C" four cylinder cars and there are soooooo may of them around using their original fans, why are "A"s so susceptible to blades breaking off ?????

Is it because Model "A" drivers push their cars to current speed limits and treat 86 year old vehicles like modern cars ?????

No, it's because of how they were made and the fact they are almost 90 years old.

[Mike V. Florida]

Originally Posted by denniskliesen

I noticed a plastic fan is much smaller in diameter. Are they all like that?

The six blade? Yes.

[Tom Wesenberg]

Originally Posted by al's28/33

Here's my question.....

Since the FORD replacement fan 46-8600 was also issued for the '33-34 Model "C" four cylinder cars and there are soooooo may of them around using their original fans, why are "A"s so susceptible to blades breaking off ?????

Is it because Model "A" drivers push their cars to current speed limits and treat 86 year old vehicles like modern cars ?????

I am thinking the same thing. With a speed doubled, the forces are squared, not by doubled. So, driving at 60 is 4 times the forces as 30 MPH.

[steve s]

Originally Posted by Tom Wesenberg

I am thinking the same thing. With a speed doubled, the forces are squared, not by doubled. So, driving at 60 is 4 times the forces as 30 MPH.

Actually, it is kinetic energy that goes as the square of speed; force (and momentum) is linear.

The problem with the old fans, in addition to poor design of Model A originals, is that with repeated flexing metal "work hardens," becomes brittle, and finally breaks upon further flexing. Bajillions of Model A vibrations eventually do the deed.

I ran an "original" four blade for several years on my A, but when it came time to restore the car I got to remembering all the times when I had reefed on one of the fan's blades to fine tune the position of the timing pin. Sometimes I could feel the blade bend when I was doing this, so, when I was done with the tuneup, I would bend it back so it looked about right--a recipe for accelerating the natural vibrational work hardening. It occurred to me that I was probably not the first one to have done that to my old fan, and opted for more modern replacements. I don't believe that the original propeller fans would bend under this abuse, but I had heard too many scary stories about them.

[ModAfan]

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"My recommendation, use a new two blade fan with engine side pans."

What is it that the side pans add to the equation? Do they funnel the air around the engine?

[denniskliesen]

I think the side pans help blow more hot air in around the brake and clutch pedals.

[WHN]

Ideally the side pans allow the air to flow evenly around the engine.

Something like a wind tunel. The air flow goes out the sides of the hood and around and down the back of engine. Without disruption from air coming up from under the car.

Helps with cooling the oil return pipe and carborator.

If it wasn't needed, Henry would not have used them.

[d.]

engine side pans...exactly...they create a path for the cooling air to flow over the engine and exit through the hood louvers, as intended. Otherwise you have no flow and air comes up off the road and mixes with everything under the hood...the side pans are there for a very good reason.

[steve s]

Originally Posted by WHN

Ideally the side pans allow the air to flow evenly around the engine.

Something like a wind tunel. The air flow goes out the sides of the hood and around and down the back of engine. Without disruption from air coming up from under the car.

Helps with cooling the oil return pipe and carborator.

If it wasn't needed, Henry would not have used them.

Originally Posted by d.

engine side pans...exactly...they create a path for the cooling air to flow over the engine and exit through the hood louvers, as intended. Otherwise you have no flow and air comes up off the road and mixes with everything under the hood...the side pans are there for a very good reason.

Have you guys seen any actual air flow data to support these claims? I'm not disputing them, just questioning them. For example, I don't understand why air swirling up from below wouldn't be cooler and more effective than air that's been heated by passing through the hot radiator which would then be carrying the motor's heat back to the motor. Might the pans be intended to reduce road dust in the engine compartment?

[WHN]

There is a reason that the pans were put on these cars.

Dust could be one. However, I think air flow is the most important reason.

Unobstructed air will move more directly and much faster allowing for better cooling.

I have never had overheating problems in any of our Model A's. All have had engine pans.

Think of airplane wings, or even air ducts. Direct the air over surfaces you need cooled.

The great think about Model A's is we all have a view but there is no one left to tell the truth.