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351c fan
#1
HI, having a strange engine vibration, and checking that all the plugs were firing and good, I noticed that the fan looked like it was missing a blade. upon inspection I found it only has 5 blades and not evenly spaced. are they indexed to the engine? would/will a 6 blade fan be better?
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#2
I believe Ford made 5 blade fans, and not having the blades evenly spaced cuts down on fan noise, not un common. Perhaps your vibration isn't there. Has the outer ring of your crankshaft harmonic balancer given way and moved? Possibly a bad engine or trans mount?
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#3
thanks, will check them out.
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#4
don blanchard.

Since I believe your car is a 72, there is some additional fan info you need to be made aware of as you look for your vibration.  Ford was transitioning from five blade flex fans to seven starting with the 1972 model year. The seven blade versions were fracturing resulting in a massive recall. The recall replacement five blade fans were suffering the same fracturing problem and resulted in several fan part numbers being issued.
I'm posting of couple of links where this issue was discussed at length with a lot of information. I will say that if wanting to remain as original as possible, the  (D9AZ-8600-A) was the final fan issued and was  a "Fix" that worked. Although my 71's were not involved in the fan issue, I have changed them to a clutch style fan since the original postings. (Less noise and engine load) 
After you have read the the postings you should be able to determine which fan you have and if there is any corrective action you need to take.     Smile
  
https://www.7173mustangs.com/thread-corr...9az-8600-a

https://www.7173mustangs.com/thread-chec...k+your+fan

Steve

No Officer...I really don't know how fast I was going, my speedometer stopped at 140!
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#5
The odd spacing for the blades is to help stop any harmonic vibrations. If you have a rotating part and hit just the right harmonic vibration it will fail in minutes. I still have my killer fan on my Mach 1, lol.


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#6
Read the first link secluff listed!! Re my posts. The other post by bentworker is just plain scary to look at. That would have been the guy's neck had he been leaning over the rad. and that wasn't even a Ford (Fram) fan.
Just be very careful when dealing with high speed fans and harmonics.
Geoff.

I learn something new every day!
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#7
A quick way to diagnose a vibration cause by an engine driven accessory is to remove the drive belts and run the engine. If the vibration persists, it's not those accessories.

If you decide to swap to the clutched fan (you'll thank us, trust me) the info is below.

The clutch you need is the Hayden 2710. The fan blade is Derale 18" 17118.

https://www.rockauto.com/en/moreinfo.php...2&jsn=2293

https://www.amazon.com/Derale-17118-Clut...B004XONYK2


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#8
I did the same as Hemikiller, got rid of that killer fan and replaced it with the clutch fan. I was missing a blade and some of the other ones were starting to fail. I noticed a vibration that led me to the fan. I still don’t know how nothing got damaged from throwing one of the blades. I had no damage, got super lucky and it went down instead of up.

run_horse Run Horse Run!
John 72 Q Code
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#9
runninpony 
I've installed a 6-blade fan on mine and so far I'm happy with it.

71-73 Mustangs never die, they just go faster!
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#10
(08-19-2019, 07:12 PM)Hemikiller Wrote: A quick way to diagnose a vibration cause by an engine driven accessory is to remove the drive belts and run the engine. If the vibration persists, it's not those accessories.

If you decide to swap to the clutched fan (you'll thank us, trust me) the info is below.

The clutch you need is the Hayden 2710. The fan blade is Derale 18" 17118.

https://www.rockauto.com/en/moreinfo.php...2&jsn=2293

https://www.amazon.com/Derale-17118-Clut...B004XONYK2
yup, did the belt thing.  thanks for the info on clutch fan.
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