5 Blade Fan Help Please !

[Rick B.]

Unfortunately today I managed to badly mangle the cooling fan on my 1972 LS5 (non AC).
It is bent way beyond any conceivable method of repair......
Given that this car is completely original, can anyone advise of the likelihood ( however remote ) that I might find a close-to-exact replacement for it?
I have spent the night searching various part #'s online tonite and to no avail.
In fact I'm not even sure anymore what the correct part # would have been for this fan ( possibly a #3991420?).
The center opening to accept the clutch hub is 2 5/8" dia. but it seems there are alot of "one size fits all" reproductions out there with claims of them fitting almost everything....
I hope someone can enlighten me please, it would be very much appreciated.
Thank you !
Rick

[Joe L.]

Re: 5 Blade Fan Help Please !

Unfortunately today I managed to badly mangle the cooling fan on my 1972 LS5 (non AC).
It is bent way beyond any conceivable method of repair......
Given that this car is completely original, can anyone advise of the likelihood ( however remote ) that I might find a close-to-exact replacement for it?
I have spent the night searching various part #'s online tonite and to no avail.
In fact I'm not even sure anymore what the correct part # would have been for this fan ( possibly a #3991420?).
The center opening to accept the clutch hub is 2 5/8" dia. but it seems there are alot of "one size fits all" reproductions out there with claims of them fitting almost everything....
I hope someone can enlighten me please, it would be very much appreciated.
Thank you !
Rick

Rick------


GM #3991420 is what you need. This fan blade assembly usually does not have a part number on it. It's long-since GM discontinued and I don't know if it's reproduced.

A better performing fan blade assembly that will work perfectly for your application but which is configurationally incorrect is GM #342715. However, it's also long-since discontinued.

[Rick B.]

Re: 5 Blade Fan Help Please !

Joe, I knew you'd come to the rescue !
Thank you as always for doing so.
While obviously I would hate to stray from original parts I realize sometime it is not feasible to find them.
However would there not be another 5 blade alternative that you are aware of?
I would also assume if I went to a 7 blade fan like this replacement is I would no longer be able to use my original Schwitzer fan clutch.
Am I correct in this? Finding something that could/would work with the same bolt spacing could be a challenge .

[Frank D.]

Re: 5 Blade Fan Help Please !

There are repros around (but pricey), I know nothing of the quality but have dealt with this vendor previously with good results...however the ad says this part number is only used through 1970. From the ad I can't tell if its ready to ship or out of stock, prob a phone call needed.

[Jimmy P.]

Re: 5 Blade Fan Help Please !

Rick,
Just sent you a PM.

[Rick B.]

Re: 5 Blade Fan Help Please !

Frank - thank you !
I saw that one as well and am thinking it is "mislabelled" on their site since it appears to be the same one Paragon has on their site but which is listed as having a different P/N and clutch fan bolt spacing.
I will call them and see but am not holding out much hope !

Jimmy, I replied to your PM. Thanks as well!

[Ralph S.]

Re: 5 Blade Fan Help Please !

I have a 3955182 7 Blade What is the application for it.

[Rick B.]

Re: 5 Blade Fan Help Please !

It is for a 1972 big block car and no A/C.
It is a fairly high horsepower engine now that I rebuilt it and I learned the hard way that under severe torque the engine most certainly DOES move up !!!!

[Leif A.]

Re: 5 Blade Fan Help Please !

[QUOTE=Rick Bandura (30672);815528]It is for a 1972 big block car and no A/C.
It is a fairly high horsepower engine now that I rebuilt it and I learned the hard way that under severe torque the engine most certainly DOES move up !!!!
Rick,
Sorry for your mishap. May want to check those motor mounts.

[Rick B.]

Re: 5 Blade Fan Help Please !

That was my first instinct however they, as well as the tranny mount, seem perfect.
There was never much clearance between the top of the radiator ( canted back ) and the fan blade at the 12 o'clock position ( maybe 1/2 inch at most ) - so given the hard launch that I did yesterday it is probable that the worst confluence of factors resulted in disaster. In hindsight it could have been much worse.
Thx !

[Joe L.]

Re: 5 Blade Fan Help Please !

Joe, I knew you'd come to the rescue !
Thank you as always for doing so.
While obviously I would hate to stray from original parts I realize sometime it is not feasible to find them.
However would there not be another 5 blade alternative that you are aware of?
I would also assume if I went to a 7 blade fan like this replacement is I would no longer be able to use my original Schwitzer fan clutch.
Am I correct in this? Finding something that could/would work with the same bolt spacing could be a challenge .

Rick------


There is no other Corvette 5 blade fan that will work for your application, at least none that will work without modifying/changing the waterpump and changing the fan clutch.

There was a significant change for Corvette fan blade assemblies for the 1971 and later period compared to the 1970 and earlier period. 1970 and earlier fan blades use a 3" bolt circle for fan blade-to-fan clutch and a 2-3/8" center hole. 1971+ fan blades use a 3-1/4" fan blade-to-fan clutch bolt circle and a 2-5/8" center hole. While there are several pre-71 5 blade fans, none can be used on a 1971+ without also changing the fan clutch and waterpump (hub and pilot shaft). Changing these also requires changing the waterpump pulleys.

The only 1971+ Corvette 5 blade fans were the GM #3991420 and the 1980-82 GM #14023200. The 14023200 is a completely different configuration and I believe it has to be used with the GM #14047080 fan clutch. Neither of those are currently available.

It is possible that there exist some non-Corvette application fan blade assemblies of 5 blade configuration and 3-1/4" bolt circle that will work but I have no information on that.

The GM #342715 blade assembly that I mentioned has the requisite 3-1/4" bolt circle and 2-5/8" center hole. However, this is a 7 blade fan with different blade configuration. It will work just fine with your existing fan clutch (or any other 1971-79 Corvette fan clutch). While the 342715 is GM-discontinued, I have found that it is available in reproduction. As far as I can tell, the 3991420 is not currently reproduced.

You should be able to find a good, serviceable used 3991420 on eBay. Make sure, though, that the seller guarantees that it's not bent or damaged. You don't want ANY bent or damaged piece. Any "as-is" piece is a "crap shoot".

[Joe L.]

Re: 5 Blade Fan Help Please !

There are repros around (but pricey), I know nothing of the quality but have dealt with this vendor previously with good results...however the ad says this part number is only used through 1970. From the ad I can't tell if its ready to ship or out of stock, prob a phone call needed.

Frank------

The seller has his years of application and part number mixed up. A 66-70 fan clutch will not work on a 1971+ application without other modifications/parts changes.

The GM #3991420 is a 1971-79 Corvette fan clutch. It will not work on a 1966-70 Corvette without other modifications/parts changes.

To determine what it is, one would need to know the bolt circle size and the center hole diameter. I suspect it's the 3" bolt circle and 2-3/8" center hole. If so, it's likely a GM #3888366, a very-much-in-demand 1966-70 Corvette fan clutch.

[Joe L.]

Re: 5 Blade Fan Help Please !

I have a 3955182 7 Blade What is the application for it.

Ralph-----


The GM #3955182 was used for some 1969 applications with C-60 and 1970 with L-46 and C-60. Later, it became SERVICE for all 1966-70 applications originally using the GM #3888366 fan blade assembly. It will not work for any 1971+ Corvette application without changing/modifying the waterpump, changing the fan clutch, and changing all waterpump pulleys.

[Joe L.]

Re: 5 Blade Fan Help Please !

That was my first instinct however they, as well as the tranny mount, seem perfect.
There was never much clearance between the top of the radiator ( canted back ) and the fan blade at the 12 o'clock position ( maybe 1/2 inch at most ) - so given the hard launch that I did yesterday it is probable that the worst confluence of factors resulted in disaster. In hindsight it could have been much worse.
Thx !

Rick------


If you have the correct locking style motor mounts, the engine should not be able to rotate more than about 3/8".

[Bob W.]

Re: 5 Blade Fan Help Please !

Rick, Call David Sokolowski (310)329-5334 I was told that he has a lot of parts for all years.He has a lot of ads in the Driveline.

Bob