Topic: Aux Fan
in Forum: C3 Cooling and Heating Systems
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The prior owner put an aux tranny cooler and an aux electric fan on my 72.
I saw a radiator guy yesterday who has been in the business since '71. I have some cooling issues, the car runs rough, at about 200 degrees. He told me to let him service the radiator and remove that electric fan. He says they block airflow and create turbulence.
He also told me to lose the flex fan and go back to original steel. He thinks that a refurbished radiator and steel fan will be better than my current setup.
What do you guys think?

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Considering the factory gauges aren't all that accurate a reading of 200 degrees isn't bad for these cars to begin with. I would use a laser thermometer to get a reading from the upper radiator hose when it's up to temperature and when the thermostat opens and compare the two readings.
I agree with losing the flex fan. They aren't very good at low cruising speed and higher rpm's since the blades flatten out as the rpm's increase. I would go back with the OEM fan. I think those had the fan clutch setup. As far as the electric fan I don't believe it blocks or disturbs air flow (unless the fan is blowing in the wrong direction) since some '78-'80 w/HD cooling and all '81-'82 vettes came with a factory electric aux fan. Those fans didn't come on until approx. 239 degrees which is pointless imo.
It would probably be a good idea to have the radiator boiled out or even recored if need be. They do get plugged up inside over time. I had mine recored many years ago. The core was about 1/3rd plugged solid. My old engine ran at 195-200 degrees all day long with a clutch fan and aux fan in place.
The same radiator with twin electric fans keeps my new "LS1" running at 200 degress all day long in 90 degree weather.
I would wait for Joel to comment here on the auxiliary tranny cooler. Thats definitely his area of expertise.
TKO500 5 spd.
Borgeson Steering Box
Born 8/1981
Sequence #3975

Click here to see more pics of my Vette on CarDomain.
Lifetime Member #26

Moderator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
I agree with having the rad cleaned, and going back to the original style fan/fan clutch over the flex fan. Flex fans are pretty useless, imho...but that's just me.
Having the aux trans cooler shouldn't cause any overheating issues if the rest of the system is clean, and working properly. If you do pull the rad for service, and you have A/C, be sure to blow thru the A/C condenser from behind, and clean it really well. You might be surprised at what might blow out of there....
Having the aux trans cooler shouldn't cause any overheating issues if the rest of the system is clean, and working properly. If you do pull the rad for service, and you have A/C, be sure to blow thru the A/C condenser from behind, and clean it really well. You might be surprised at what might blow out of there....

Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
I agree with both Joel and Sarge on the radiator cleaning. If Im reading correctly you have a 72? If so is the original shroud still on the car. These shrouds are critical for the correct air to be pulled thru to create proper cooling. They also need to have the seals in place around the shroud. As for the flex fan take it off as soon as possible (IMO) and go back to an original clutch fan type. I have seen flex fans loose a blade and go thru hoods. Also horror stories of people being hit by pieces when they come apart. As for the electric fan I would think he meant since its an auxillary it blocks air flow from your flex fan. I run electric fans only on my 72 and I am very happy with them. But any fan needs to be properly shrouded to allow them to draw as designed.
P.S. if you decide to go back to an original style fan and cant find one let me know. I have the one from my 72 that I am not using.
Best of luck,
Rodney

P.S. if you decide to go back to an original style fan and cant find one let me know. I have the one from my 72 that I am not using.
Best of luck,
Rodney

Yes... He doesn't like an aux elextric fan. I turn it on and off manually. If it's off I could see it blocking airflow since it's about 1/2 the size of the radiator. The blades would just sit still and cause problems I suppose.
He also said the nylon mounts that pass thru the radiator to attach the aux fan can wear thru the cooling tubes in time. Does that make sense?
Here's what my setup looks like:

|UPDATED|12/15/2014 4:39:03 PM (AZT)|/UPDATED|

|UPDATED|12/15/2014 4:39:03 PM (AZT)|/UPDATED|


Moderator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
That set-up doesn't look very efficient to me, either. The lectric fan is blocking some airflow for the flex fan. With a normal fan clutch set-up, if you want more, or an auxiliary fan, you should mount it on the other side of the radiator, and set it up to PUSH air. Then you'll have the best of both worlds for your '72 vehicle.
I'm inclined to agree with the plastic thru-pin holding the cooler to the rad/condenser. If they are not installed properly, they can poke holes in the core, or wear thru them. The operative word here is "properly".
I'm inclined to agree with the plastic thru-pin holding the cooler to the rad/condenser. If they are not installed properly, they can poke holes in the core, or wear thru them. The operative word here is "properly".

Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Does the shroud look right to you?
The PO is Bubba on steroids. He builds dragsters and races them at the local strip. He started on the Vette but decided a 'Cuda was a better dragster so he sat the Vette in a barn for 10 years. I prolly paid too much for her ($16,000) but it's been a good project and learning experience.
What Bubba did well:
-engine work (rebuild with chrome valve guides, more aggressive compression 10:1, bored to 360). It's one fast 350😏
-edelbrock chrome intake manifold
What Bubba didn't do well:
- yanked the AC and threw away the compressor
- rebuilt the tranny and pulled the shifter rod with a chisel (cost me $1,000)
- sealed the windshield with silicone on the inside causing windshield frame rust (cost me $1,500)
- tranny pan with cooling tubes but he saved the original
- used the interior to store lawn chairs...lots of gouges but I needed to replace everything anyway
- virtually no original screws...anywhere
- somehow bent the right trailing arm, cost me $500 for a used one
I asked for a project and I got one!
But...the restoration got me an invitation to the Boise Roadster Show! And that's with a drivers paint job!
|UPDATED|12/16/2014 8:07:44 AM (AZT)|/UPDATED|
The PO is Bubba on steroids. He builds dragsters and races them at the local strip. He started on the Vette but decided a 'Cuda was a better dragster so he sat the Vette in a barn for 10 years. I prolly paid too much for her ($16,000) but it's been a good project and learning experience.
What Bubba did well:
-engine work (rebuild with chrome valve guides, more aggressive compression 10:1, bored to 360). It's one fast 350😏
-edelbrock chrome intake manifold
What Bubba didn't do well:
- yanked the AC and threw away the compressor
- rebuilt the tranny and pulled the shifter rod with a chisel (cost me $1,000)
- sealed the windshield with silicone on the inside causing windshield frame rust (cost me $1,500)
- tranny pan with cooling tubes but he saved the original
- used the interior to store lawn chairs...lots of gouges but I needed to replace everything anyway
- virtually no original screws...anywhere
- somehow bent the right trailing arm, cost me $500 for a used one
I asked for a project and I got one!
But...the restoration got me an invitation to the Boise Roadster Show! And that's with a drivers paint job!
|UPDATED|12/16/2014 8:07:44 AM (AZT)|/UPDATED|

The shroud looks stock to me. These cars need the foam seals between the shroud and the radiator and the hood.
If this is not an NCRS type car, and you want a/c, I'd go back with a Vintage Air unit. Cools better and less intrusive
to the engine compartment.
If this is not an NCRS type car, and you want a/c, I'd go back with a Vintage Air unit. Cools better and less intrusive
to the engine compartment.
As good as it looks now...I don't have the patience to take it all the way to NCRS level. So Vintage Air might be my next move if I can get it to run cooler. AC + hot engine = bad news!


Ash Fork, AZ - USA
Joined: 4/18/2007
Posts: 1058
Vette(s): 1981 Red Interior White exterior
OK, here is what I have and it is definitely wrong. I have an aftermarket flex fan, like your's but mine is a pretty blue, and the electric fan that will only come on around 240 degrees. I also have the original radiator which I had re-cored about 5,000 miles ago. The front bumper extension is not attached properly. The PO broke part of the bracket so now instead forcing nice cool air in toward the radiator it blocks air coming from under the car. On the original, probably inaccurate, temperature gauge I was reading about 210. I had a significant drop in temp once I installed new roller rockers, down to 190. I have not come close to overheating. Consider I was driving in 95 degree heat and stuck in traffic on an interstate for over an hour during the NCM Caravan this past summer I feel pretty good about the cooling properties of my car. That being said I'll switch to a steel fan this summer.
Dave C..........My mantra: I can not be bought!! Long and short term leases available.
In the words of Zora Arkus-Duntov "Is your seat belt fastened? Alright, Let's go"
Yeah, I know, Shut up Dave.
Yeah, I know, Shut up Dave.
Lifetime Member #192


in Forum: C3 Cooling and Heating Systems
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