# Fan Clutch



## olde-goat (Feb 1, 2009)

I am in the process of going through all my parts for my 65 GTO tri power auto convertible restoration; cleaning, painting,repairing etc. When I bought my car it came in three truckloads. Car is not together but would like to know if fan clutch is OK. What do I look for to determine its condition, or do I have to have it on a running car?


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## Too Many Projects (Nov 15, 2008)

Any signs of oil seepage at the shaft is not good and it should turn with some resistance. If it turns easily, the oil is probably gone. Also, if the shaft has ANY play at the hub, the bearing is bad.


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## olde-goat (Feb 1, 2009)

Actually this clutch looks like it came out of the box. No play between shaft and hub, and slight resistance when turned. I am not sure of how these work. I was assuming that once the unit is warmed up (heat gun) it should lock up.


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## Too Many Projects (Nov 15, 2008)

There are 2 types of clutches. Thermostatic and viscous. A thermostatic clutch will lock up or turn harder when heated, a viscous doesn't. If you don't see a thermo plate on the front of the clutch it is viscous. A viscous turns all the time but turns slower at higher rpm to drain less hp. The fluid lets the blades "slip" in the air to slow down and then holds them to pulley speed as the rpm drops, drawing in more air at low vehicle speed. The only way to test the actual operation of this clutch is on the engine. By your description, it is probably OK.


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## khinton (Jun 22, 2008)

What works best the orginal type fan clutch or a flex fan--opinions wanted.


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## Too Many Projects (Nov 15, 2008)

khinton said:


> What works best the orginal type fan clutch or a flex fan--opinions wanted.


A flex fan is usually a direct bolt onto the water pump and can howl loudly at road rpm. I would opt for a THERMOSTATIC clutch and factory 7 blade fan.


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## Rukee (Feb 8, 2007)

:agree use the clutch fan.


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## khinton (Jun 22, 2008)

Thanks--Do you know where to get the factory 7 blade fan?--mine is a 68


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## Too Many Projects (Nov 15, 2008)

khinton said:


> Thanks--Do you know where to get the factory 7 blade fan?--mine is a 68


The fans come up on ebay quite often or there is a reproduction available.

Also, local swap meets are a good source but know what you need for size, bolt pattern and desirable pitch before buying one there.


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## khinton (Jun 22, 2008)

Thanks--will look for one--want to change from the flex fan that came on my car:cheers


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## khinton (Jun 22, 2008)

Found one on ebay--suppose to be from an orginal a/c 68 GTO--no leaks show and seems to have some resistance--Can any one tell me from the enclosed picture what type it is-- viscous or thermostatic. Now to clean it up.


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## Too Many Projects (Nov 15, 2008)

khinton said:


> Found one on ebay--suppose to be from an orginal a/c 68 GTO--no leaks show and seems to have some resistance--Can any one tell me from the enclosed picture what type it is-- viscous or thermostatic. Now to clean it up.


That is viscous. Try it, if the engine wants to overheat in slow traffic, you can change the hub to thermo for about $65 at NAPA.


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## khinton (Jun 22, 2008)

Thanks--I sort of thought that was ths case--but I also thought pontiacs used thermostatics:confused--so what are the odds that this year 68 clutch fan operates as it should and if it does is the viscous as good as the thermo for cooling--In other words should I just go to napa and have it changed --and is this like a rebuilt (will they also make sure the blade are in alingment too):cheers


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## Too Many Projects (Nov 15, 2008)

By the application charts I find, Pontiac used thermo clutch's mostly on A/C cars. The viscous was also used on them in certain years and HD cooling systems, such as the performance models. I would give it a try and see if it works for you. If not, change it. The thermo hubs I saw on NAPA are all new construction and they don't do anything with the blades. You remove the hub and install the new one.


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## khinton (Jun 22, 2008)

I have one blade that sticks up higher than the others ( about a 1/2inch)when it sits on the mounting hub when placed on horizontal--will this cause viberation: if so how can tis be staightend professionaly--trying to keep the car original--see photos--one with the pink square sits higher than the rest of the blades


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## Rukee (Feb 8, 2007)

I don't think that will cause a problem.


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## Too Many Projects (Nov 15, 2008)

Rukee said:


> I don't think that will cause a problem.


:agree Once you mount it, you might be able to tweak it back by hand too.


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## khinton (Jun 22, 2008)

Found another that came off a 68 GTO air condition car but it looks like when it is installed it wont protrude into the fan shroud (be even) opening at all. The flex fan that I have installed protrudes by almost 1/2 of the width of the fan blade with it's spacer--what is correct --any sugestion?

(Was not able to bend the hub on the old one)


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## Too Many Projects (Nov 15, 2008)

khinton said:


> Found another that came off a 68 GTO air condition car but it looks like when it is installed it wont protrude into the fan shroud (be even) opening at all. The flex fan that I have installed protrudes by almost 1/2 of the width of the fan blade with it's spacer--what is correct --any sugestion?
> 
> (Was not able to bend the hub on the old one)


Half way into the shroud is perfect.....behind it is a no-go. It will pull air from around the shroud. Can you use the spacer with the clutch fan ?


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## khinton (Jun 22, 2008)

Some where I read that using a spacer with a clutch fan will hurt the water pump? I think I read that in a year one catalog--but maybe I need to just keep the flex fan with the spacer--I'm now seeing the clutch fan blsde will prboably not clear the nut that holds the power steering pump pulley (the fan would need to be foward to clear) these parts , as far as I know are all stock parts--I can't figure what is wrong unless it is because ths fan unit is for an air conditioned car--mine is not--??:confused


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## geeteeohguy (Feb 2, 2008)

I've had mixed results with fans....i don't like the weight of a clutch fan but I do like the quiet. I installed a GM flex fan from a '69 Caddy onto my '67 GTO about 15 years ago and solved my overheating in traffic problem. It's quiet, and pulls a ton of air. I've had a performance stainless steel flex fan on my '65 for the past 25 years, and it does work, but man, is it LOUD. Just last week, I was driving the car, and thougt "man, I just have to get rid of this fan". So, I'm thinking of a quieter option!!! I don't know why the GM flex fan is quiet and the performance fan is so noisy....stiffer blades, I guess...


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