Function test for fan clutch

[Yennes]

Hi

I have an original 68 fan with fan clutch wich seems original as well. However these parts are 50+ years old and I am not sure if they work properly.

I was wondering if there is a way to test the fan clutch. Maybe someone did it and give me a hint.

I was thinking about to put the fan on a drilling machine and hold the fan in my hands. When the machine is spinning I would blast hot air onto the ??spring scroll?? and wait if something is changing.

Maybe some technical terms are wrong! Please correct me!

Any help appreciated and thanks fbbo!
Yannik

 

[Kern Dog]

I can only guess that there might be some test that is mentioned somewhere in a factory service manual. I have a couple here but have never looked deep enough to find out. This is an interesting topic though and timely since hot weather is coming and cars will overheat if their systems are not working properly.
I use basic logic when dealing with stuff and fans are no different. To me, if the clutch freewheels by hand, it would be worthless when in use. You’d want it to slip some but not too much. It seems like you’d want it to be effective at idle and low speeds since the vehicle won’t have adequate airflow through the radiator. Higher speeds you do have enough air passing through so it seems the fan is almost redundant above 30 mph. From there, it is like the fan could slip 50% and not adversely affect the cooling capabilities.
I’m only guessing but I wonder if modern cars have electric fans that can shut off at freeway speeds. My bonehead logic tells me that it would make sense at that point.

 

[RemCharger]

If everything is hot and running , and it's blowing a ****-ton of air.. it's good!

 

[Yennes]

If everything is hot and running , and it's blowing a ****-ton of air.. it's good!

Yes it does, but I have no fan shroud installed and it blows the air more sideways than to the engine.

I have heat problems and as @Kern Dog said already, weather is getting hotter next month. That is why I made this post.

I assume that the radiator is not clear and has all its water flow and performance. I will install a shroud anyway but maybe I will get a new mesh into the radiator. It is original as well and seems like it never got a new one.

And if the fan will run properly too, it should be all COOL for the summer…

Thanks
Yannik

 

[khryslerkid]

Yes it does, but I have no fan shroud installed and it blows the air more sideways than to the engine.

I have heat problems and as @Kern Dog said already, weather is getting hotter next month. That is why I made this post.

I assume that the radiator is not clear and has all its water flow and performance. I will install a shroud anyway but maybe I will get a new mesh into the radiator. It is original as well and seems like it never got a new one.

And if the fan will run properly too, it should be all COOL for the summer…

Thanks
Yannik

A fan shroud can make a big difference. You want 1/3 of the fan sticking out of the shroud toward the engine.

 

[Black_Sheep]

Look for oil residue where the shaft goes into the clutch, also try to spin the fan by hand. Even cold there should be some resistance. If it spins freely it is probably failing.

 

[1967coronet]

If you run the car up to operating temp and then shut it off ,open the hood and try to spin the fan after it has stopped . If it is tight it probably is good.
I second the get a shroud post, Stick a new 16lb. Cap on it.

 

[RJRENTON]

If everything is hot and running , and it's blowing a ****-ton of air.. it's good!

FYI.....air flow is measured in CFM (Cubic Feet per Minute) and at some static pressure point (S.P.) or some quantifiable value......how much air flow is a "****-ton"??......Grams or kilo-tons or pounds per year or seconds or hours......difficult to determine exactly how much is enough or too much ......??? to calculate.... Inquiring minds want to know....
BOB RENTON

 

[WileE]

You need a shroud. Period. That's why they installed them.

 

[kiwigtx]

I was thinking about to put the fan on a drilling machine and hold the fan in my hands. When the machine is spinning I would blast hot air onto the ??spring scroll?? and wait if something is changing.

 

[pedal2themetal]

HI,
A google search for fan shrouds for 68 came up with this explanation

Early 1968 big blocks used a metal fan shroud similar to the one used on small blocks with an Aluminum radiator. This lasted until approximately vin 2500, after that it was switched to a fiberglass fan shroud to help cure overheating problems that plagued the early cars.

good luck take care be safe
tim

 

[pedal2themetal]

I was thinking about to put the fan on a drilling machine and hold the fan in my hands. When the machine is spinning I would blast hot air onto the ??spring scroll?? and wait if something is changing.

Hi,
That won't work the clutch fan works off of the HEAT from the radiator to heat the spring in the clutch to make it grab and spin.

good luck take care be safe
tim

 

[kiwigtx]

good luck take care be safe
tim

...or at least know the fastest route to the nearest hospital.

 

[rickseeman]

Hi

I have an original 68 fan with fan clutch wich seems original as well. However these parts are 50+ years old and I am not sure if they work properly.

I was wondering if there is a way to test the fan clutch. Maybe someone did it and give me a hint.

I was thinking about to put the fan on a drilling machine and hold the fan in my hands. When the machine is spinning I would blast hot air onto the ??spring scroll?? and wait if something is changing.

Maybe some technical terms are wrong! Please correct me!

Any help appreciated and thanks fbbo!
Yannik

Well.....you stick your fingers down there and give the fan a spin with your hand. If it stops fairly quickly, it is like new. If it spins around and around, it's wore out. It's that simple. I went and worked on a 69 Road Runner with the original fan last week. The fan spun round and round. The clutch fan is too tired to pull enough air idling in traffic on a hot day. The owner doesn't do that so we left it alone. Don't try to over think this. Just reach down there and flip it with your fingers and it will tell you everything you want to know.

 

[Cranky]

Well.....you stick your fingers down there and give the fan a spin with your hand. If it stops fairly quickly, it is like new. If it spins around and around, it's wore out. It's that simple. I went and worked on a 69 Road Runner with the original fan last week. The fan spun round and round. The clutch fan is too tired to pull enough air idling in traffic on a hot day. The owner doesn't do that so we left it alone. Don't try to over think this. Just reach down there and flip it with your fingers and it will tell you everything you want to know.

Just make sure the engine is off when you stick your fingers down there.... you probably know that but there just might be someone here who doesn't. Over the years I've run into a few dummies that acted like they knew a lot about cars when they didn't know a dad gum thing about them!

 

[Geoff 2]

There are tests for fan clutches but they are very subjective & do not give a really definitive answer as to the clutch condition. Original 68 clutch & you have overheating???

It is a no-brainer: time for a new clutch. They are not that expensive.
They clutches come in three levels: standard, heavy duty & severe duty. Since you have 'heat problems', I would get the severe duty clutch. It has less slippage & pulls more air.
Also a shroud as others have suggested.

 

[RemCharger]

FYI.....air flow is measured in CFM (Cubic Feet per Minute) and at some static pressure point (S.P.) or some quantifiable value......how much air flow is a "****-ton"??......Grams or kilo-tons or pounds per year or seconds or hours......difficult to determine exactly how much is enough or too much ......??? to calculate.... Inquiring minds want to know....
BOB RENTON

Thank you!! Will look into what CFM means! Never too young or old to learn!

 

[Kern Dog]

There are tests for fan clutches but they are very subjective & do not give a really definitive answer as to the clutch condition. Original 68 clutch & you have overheating???

It is a no-brainer: time for a new clutch. They are not that expensive.
They clutches come in three levels: standard, heavy duty & severe duty. Since you have 'heat problems', I would get the severe duty clutch. It has less slippage & pulls more air.
Also a shroud as others have suggested.

Be ready though. A fan clutch with minimal slippage will make the fan R O A R !!
I've been through this. A LOUD fan really is annoying.

 

[kiwigtx]

Thank you!! Will look into what CFM means! Never too young or old to learn!

Quantifiable Value = QV.

 

[diesel_lv]

I've got a direct drive 19" 11 blade reverse rotation fan on my '67 Coronet w 496" stroker n serpentine belt. Can't run a fan clutch due to space limitations and direction. In 125° summers, I cruise at 180° easy and idle after 10 minutes idling w a/c on at about 210° which is normal. Have factory shroud. But it is very loud from the fan roar. Here's a diagram of proper fan/shroud placement.