MILO

How can I tell if a clutch fan is not working properly? I have a vague understanding of how it works. Last night I took the fan and clutch out of the car, applied heat to the round spring and visually saw the valve open. I also removed the spring and the valve moves freely. The issue is when I applied heat to the spring and the valve moved there was absolutely no difference in the amount of effort to spin the fan. Whether it was cold or hot there was some resistance but no lock up as I was to believe.

So is there a way to test these things out of the car or must it be spinning on the car and listen for the fan to kick on? BTW way the car is a 79 with a low mileage new clutch fan from Ecklers part #23047.

Comments are welcome ....

rihwoods

http://www.haydenauto.com/fce3.htm

Don't think you can bench test it that way....

MILO

I didn't think I could, but I had to ask. Thanks for the link. I guess the best indicator is that since I don't here the increase in fan speed when the car is hot, the bet is on that it's shot. I would think at 230+ degrees the fan would be engaging and I could hear more air being moved.

rihwoods

Some are quieter than others..I have a thermal type that comes on based on underhood temps and if I'm driving with windows down,sometimes I barely hear it...
here is how I check them....engine off...I rotate fan by hand and if I feel a combination of resistance and it turning free in that rotation,I assume it is toast...also,check for any play or wobble... I learned this when a bad fan clutch took out my water pump and radiator once...remember,they operate on the same shaft....
Hope this helps..
Rich`

MILO

"Stop the engine and, using a glove or a cloth to protect the hand, immediately check the effort required to turn the fan. If considerable effort is required, it can be assumed that the coupling is operating satisfactorily. If very little effort is required to turn the fan, it is an indication that the coupling is not operating properly and should be replaced.

If the clutch fan is the coiled bi-metal spring type, it may be tested while the vehicle is being driven. To check, disconnect the bi-metal spring, and rotate it 90 degrees counterclockwise. This disables the temperature-controlled free-wheeling feature and the clutch performs like a conventional fan. If this cures the overheating condition, replace the clutch fan.

Another way to check it is to listen to it. Let the engine idle and when the clutch fan heats up enough to engage, you'll hear a change in sound. It will sound like a roar which indicates that it is actually pulling air."

I'll be testing this tomorrow and post the results.

ruby76

So does that basically make it a direct-drive fan then?

rihwoods

Interesting about the spring disconnect method...this checks the vicosity of the fluid in the clutch,I think....and makes it function like a non-thermal clutch it appears....

ruby76

Im not sure how that would help, if you think it isn't working, then taking the spring out and following those directions would/could allow the car to get hotter? Hmmm.. I see, I guess if it did get hotter, then you would know that it WAS locking up thermally, if it remained same symptoms, then it wasn't locking up to begin with. okay, I've talked myself into it

rihwoods

I was puzzeled at first myself,but I think the idea is to by-pass the thermal couple thing to test it...after I had one of these clutches fail and take out my water pump and radiator,I don't mess around,which is why I check them by hand...I'm not convinced standing there watching the turkey spin tells you much...especially if the viscosity of the fluid is just starting to break down....I check mine every 600 or so miles....gun shy...

MILO

The one I have on my car now is the second one since I've owned the car. The original one scraped the fan shroud each time a hard right or left turn was made. I finally figured it out when I accidently moved the fan blade by hand and clutch wobbled. Since then I've been battling an overheating problem that has been slowly getting worse. I pulled the jets out of my Holley 650 spread bore from the primary side and they were #59. Seem kinda of low since I no it doesn't have a stock cam in it. Plugs look kinda "dry" too. I put in #64 to see what it does with the heat.

The past few weeks I've eliminated everything except the clutch fan, Carb jetting and timing. According to LARS I have an advance limiting dist. So I'll have to try to get more advance by placing with the intial timing and porting the vacuum advance to a manifold source. Pure process of elimination here.

Back to the clutch fan, if the clutch is not engaging at high temps (like on the Hwy is where I overheat) the fan could be blocking the flow of air instead of moving it along. Locking the valve on the clutch 1. I should here it roaring or 2. No over heat. I hate spending money without over analyzing the situation. (ask my wife )

Thanks for hearing me out.

rihwoods

Keep us posted..believe you are the first I've heard here to try this.....

MILO

Well the above mentioned test worked. I disconnected the spring and manually locked the clutch valve to the engaged position. Went for a ride and heard the very distinctive roar of the fan. Temp was about 185. I pulled over and reconnected the spring. Within 10 minutes I was over 220 degrees while driving over 50 mph. I pulled over again and disconnected the clutch spring and manually locked the clutch valve. Drove again and with minutes I was at 185 degrees again. A new fan clutch is $60 at Napa or $79 at Ecklers and the like. So I've decided to go the electric fan route, single 16 inch and gain some efficiency. I'm amazed that this was the source of my overheating problem for at least a year.

rihwoods

HMMMM>I have a thermal clutch fan..I have heard it engage at 65 mph...mine is activated by underhood temps...think this needs some research...

ruby76

It would be interesting if you found a local C3 guy that did not have overheating problem and "borrowed" the fan clutch off of that one for a test. Might as well be "certain".