Hello. I have questions about the fan clutch on my 69 sb. Over the winter I replaced the Schwitzer style clutch on the car as it was leaking/ a seepage of the liquid inside and did turn by hand quite easily although there were no over heating problems but thought it was on it's way out.
I replaced with the same Schwitzer style from a vendor, fit fine, no cooling problems. Now however the noise from the engine compartment, I'm quite certain the (roar) is the sound of the fan and air movement is much noisier at RPM's over 2,500 than with the old fan clutch, with cold or hot motor. I don't understand why. Doesn't the fan clutch "engage" on higher revs. or highway speeds and reduce the speed of the fan and thus the noise of the fan and air movement at higher RPMs.
The new fan takes the same effort to turn by hand weather hot or cold engine and certainly doesn't free wheel . I say this because according to the C.C. vendor "with engine cold the fan should be free to turn and once the engine is warmed up the fan should be much more difficult to turn" Is this correct about easy to turn on a cold engine as mine is the same whatever the engine temperature is. So my question is why is my new fan clutch so much noisier, not at idle RPM but at higher revs. than the old one. I hope this makes sense and thanks for your help.

 

The fan clutch engages when the engine reaches operating temperature. There's a thermal spring on the front of the clutch that responds to temperature changes. On a cold engine, the fan sort of free-wheels though it's turning due to the belt and fluid friction inside the clutch. Not that I'd try it, but you should be able to easily hold or stop the fan from rotating when running a cold engine. The fan should "lock up" when the engine is hot - very similar mechanics to an automatic transmission's torque converter. This fluid drive "lock up" ensures the fan is effective at operating temps. When just shutting down a hot engine, the fan should only rotate one or two revolutions. This is a commonly advised check to make sure the clutch is engaging.

I believe the roar you hear is the fan "locking up" and moving substantial amounts of air that it wasn't doing before.

 

You tested it correctly but with the car cold start the car and shut it off after 2 minutes and turn the fan and note the resistance, then get the car to operating temps and check the resistance again, it should be harder to turn when hot.
If both tests are the same the clutch is not working correctly.

 

When I got a new fan clutch it was the same way. It got better after about 10,000 miles.

 

i agree.
op what did you buy? There are hd and regular clutches.. it should spin easy cold
here is my education..
note also as you increase severe duty it does spin a % when not engaged
https://www.corvetteforum.com/forums...re-79-l82.html

 

Thanks for the answers. I'm beginning to think the new clutch is working correctly. As to your question Interpon, it the Schwitzer sold by Cor. Central. It doesn't mention any duty rating so perhaps not severe as they would probably include that in the description.
The fact that there appears to be no difference as to being able to move by hand on a cold or hot engine and that noise wise "lock up" seems to be at about 2,500 rpm and nothing to do with temperatures as I thought it should. Maybe, as with bruiser it will take some time.
Still trying to get one of the kids to try and stop the fan at idle. JUST KIDDING. Take care and thanks.

 

Mine did the same but I had installed a heavy duty replacement clutch. Not that Im trying to argue the drawbacks but the fact that they all still apply drag and spin when not needed is one of the reasons they are known for costing 12hp or so vs an electric fan which on turns on when needed.

 

I had exactly the same issue when I replaced my fan clutch last year. Sounds like a jet on takeoff. I have a friend who works in parts and he tells me the problem is that over the years manufacturers consolidate their inventory of parts. They just don't sell enough fan clutches for forty year old cars to justify making ten different clutches. Therefore they default to making just a few, and all tend toward the heavy duty end of the spectrum, since these will cause the fewest problems in terms of cooling. I was told this was going to be a problem, so I put on the base regular duty clutch. Still noisy as hell.

 

I have new clutch fan on my old 93 chevy truck and one my 65 Gto. Both sound like a C130 taking off! My mechanic friends say the same thing about fans they are putting on customer vehicles. They also think they are just making them all the same or about the same due to poor market demand.

 

On the bright side - a C130 is a cool airplane!

 

I'm not saying this is the only solution, but electric fans are silent when you are driving. Noisy when you are idling at a stop light, sure, but if my car is moving at all, the fans stay off.

Something to consider if clutch fan noise, and power loss, is a problem.

 

It was when my original fan clutch failed that I installed electric fans.
Yes it turned into a bigger deal than I originally thought.
But none the less for several reasons I am glad I changed over.
And now with EFI and the required extra electrical demands.
Not at all unhappy.

 

Normal T/O or with the JATO bottles going?