had the car inspected in march the mechanic  said the fan clutch was running all the time taking away HP. He said it should be replaced. So I venture out on my own to replace it and started it up and its still runnig. THe engine is cold and ran from the get go.  I took it for a drive and sitting idle in gear or not in driveway it ran when ever I popped the hood.  So read the instructions and ot state the fan would run all the time but when cold it would run slower. but alwasys spins???. So did I need to put a new fan clutch on or not who is right?????? Would appreciate any info... in the books it states if yo have ac or not but in ordering the clutch it did not ask for that specific??? just v-8 350 4bbl..... no ac input I ahve ac... any answers ??? Thnaks Mark 1978 automatic

I believe the fan will always spin because it is attached to a fan belt. The fan clutch mechanism will activate due to temperature and therefore allow for more cooling action from the fan when this occurs.

Kevin is correct, the fan will always spin while the motor is turning, however, the fan clutch will allow the fan to "slip" spin while the motor is cooler, and as it warms up, the clutch kinda tightens onto the fan allowing it to spin faster(approx the speed of the pulley its attached)... rule of thumb is that when you run the engine up to tempurature, and park it, turn it off, and see how hard it is to spin the fan by hand... it should be considerably harder to move than it is when the engine is cold... however, so long as it is cooling sufficiently, i wouldn't be overly concerned with the amount of horsepower you might be loosing... it would be somewhat moot.. :)

Thanks for the info I agree with all of yo not sure why the garage said it is always runing it should be just  more at times of cooling and not sure about his comment  of robbing horsepower either, just changed mine anyway and painted the fan so it looks far better then before even is no more cooling is had...Thanks again now onto the washer bottle pump inop??? and removal???

Yes as far as I know the fan will always spin with a clutch just slower when cold and faster when the engine gets hot. I removed my original fan and clutch and installed a Flex Fan with a spacer, it really works well.

Funny this thread should come up. I am considering replacing mine with a solid mount. I am not concerned with HP, only cooling.  Mine is not good. When I shut-er down it spins for quite a time after it heats up to normal temp.  I think the clutch is shot.       I will be replacing the water pump tonite as it went on the blink on the way to work this morning.  Not leaking, hope I can get it home.   Mark

One thing I like about the clutch fan is the lack off noise. Most will see an increase in the noise level when they switch to a direct fan. I can hear my fan when the clutch locks it up. I run a 160 degree thermostat and a high flow water pump and I have replaced all my foam seals around the radiator and hood so I'm getting all my air through the radiator and not losing any air flow going around it. My fan only engages when my temp gauge gets to about 210 degrees. That only happens once in a while on a hot day in traffic. usually runs about 170 to 180 degrees.

Fan clutches will rob some HP, but not enough on a street car to worry about....I'm more concerned with it not overheating than I am about loosing  few measly HP. As long as the fan doesn't spin for more than a second or two after shutting the engine down(as Mark's is), and it's not wobbling, or leaking any fluid, or stuck solid, you're good. Any of the above symptoms require replacing the clutch.
Sounds like the shop you're using might have been trying to up-sell ya...

Me thinks Joel is rite bout yer shop..... I would be a smidgen more worried bout them fellers than yer fan.

I changed mine out fer a flex fan some time ago an I cain't hear it out thar. I hear me headers a rumblin an that makes me face light up wit a nice big smile.

I replaced mine only because the mechanic led me to believe the clutch or fan should not run al the time and it robs HP.... I di dnot kow how it could not run all the time but slower when cooler...anyway maybe its mental but did put in a new clutch spruced up the fan and looks great and spins all the time but I believe there is a little more pep in acceleration mybe I'm dreaming but it looks nice and new. Thanks BB78