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  #16 (permalink)  
Old 08-14-2004, 04:36 PM
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Originally posted by Ed ke6bnl
I just installed a heavy duty thermal clutch fan in my dually 454. but after doing it I was curious why no one has come up with a magnetic cluth operated one like an a/c clutch that would engage on a temp sensor like the electric fans do.?????? Ed ke6bnl
Hey Ed, you're a wasted talent man. You should of been an inventor. He he! Peugeot used a magnetic clutch fan set up on their 70's and 80's 4cylinder models. The fans were quite small and light - my guess was to reduce the inertia in case the clutch decided to engage while the engine was being raced through the gears. Being a vehicle inspector, I've had to test these vehicles prior to the customers purchases. With the fan suspiciously freewheeling as if nobody's home, I'd set the engine speed to 2000 RPM while I'd write the test report. With full concentration on the report writing I'd literally duck for cover as I'd hear this almightly roar as the fan clutch kicked in.
I don't think using such a set up on a heavier v8 fan would be practical. Also the safety aspect must be considered, particularly for the unsuspecting hands that may be in the area. Rob

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Old 08-16-2004, 03:42 PM
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Clutch Fan

[color=yellow]Doc Here

OK, now Does anybody know if the Clutch unit is repairable when it locks up ? and If So how?

The fan clutch on my 80 Vette has locked up, I would like to repair it if possible. Standard SBC 350' clutch units won't work in that year Vette because of the proximity of the fan to the top of the radiator, and / or shroud, I've tried a few and they either hit one or the other, or they they hit the shroud on Very cold days, when it's contracted, until it heats up and expands. (Makes some Scary noises..)

I bought one off EBAY for $50 bucks, but the Chick cashed my check and never sent it, then Claimed it was lost in the mail...(I checked with her local postmaster in a very small town, who knew her, said it was never sent) BTW Anybody buying Vette parts off EBAY, DO NOT bid from Melmyra she has a track record of taking your money and not sending the item....

So Can these be repaired? New bearings maybe? Never worked on one, so I have no Idea, usually I just got new ones and bolt Them on.

Corvette parts has them, but want a small Ransom and your first born male child for one... after already losing the $50 and cost of trying other types, I'd like to see if it can be fixed Before packing the oldest's sons bags....


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Old 08-16-2004, 04:09 PM
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I once did a dodgie repair for a friend's Corolla. The coupling had lost all its viscous fluid and the engine ran hot as a result. I seperated the 2 halves and added transmission fluid to the deeper half and re-assembled it. It was only intended as a temporary repair as she needed her car right there and then (like all women)! But believe it or not, it cooled the motor and it did'nt leak. I expected her to eventually complain but the beast kept on going. My guess is that any fluid is better than no fluid. But if you can get the viscous fluid, the better. I think Toyota used to sell the stuff in small bottles as their early couplings had little fill plugs that could be unscrewed for topping up. In your case Doc, I'd say it had seized due to total fluid loss. The dry viscous discs would most likely have welded themselves together.
I'd rebuild them on the proviso that the hub shaft does'nt have excessive freeplay in the housing bushing. Sourcing a shaft seal should be straight forward as your bearing and seal seller fella should have one in stock. The 'o' for the housing mating faces should be re-usable. I should point out that when I seperated the Corolla's viscous coupling that the large 'o' ring had become enlarged, IE, the diameter had grown due to the fluid. I cut a section out of the 'o' ring to form the correct fit and then superglued the ends of the 'o' ring together. This all may seem like extreme measures to most of you, but there's times when you got to have a go, not just for cost reasons but on principle.

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Old 01-01-2005, 10:09 AM
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Re: Clutch Fan

Originally posted by malibuman66

I have a clutch fan on my 66 Chevelle , can you tell me how this operates in general? Also yesterday I went out riding my temp was up to 190 , when I went to restart it bearly turned over. I'am running headers with a heat sheild wrap on the starter. No fan shroud on the radiator. The clutch fan came from a late model Chevy van. If I added an electric fan kit to it would that help the cooling ??

Like others have said if you have a clutch fan you need a fan shroud. Most "factory" GM fan clutchs are thermal, that is to say they operate based on tempature. Once the air coming through the radiator gets so hot (sensed by th fan clutch ), the clutch engages or locks up allowing the fan to be driven 1 to 1 with the rotation of the fan pulley. When the fan clutch is disengaged the fan partically free-wheels and its not pulling that much air.

If you add electric fans you need to cover the rear of the radiator as much as possible to allow for maximum airflow across the area of the radiator. Also you most likely would need a higher output alternator, because a lot of the older model cars had relatively low amp output alternators.

You need the correct fan shroud that fits your car. Most every GM car I've seen came from the factor with some type of fan shroud.

Originally posted by Ghetto Jet
You don't have a fan shroud? There's your problem, you need one quick. One way to tell if the clutch fan is starting to go bad, touch the front center of it with your hand, if it's all greasy, it's starting to go. How it works? The clutch fan is temperature sensitive. once it detects a certain temp the clutch fan will engage and allow the fan to operate.

the way to test a thermal fan clutch is to run the engine until it gets to operating temp. Then shut the engine off and move the radiator fan by hand. The fan should have some firm resistance to movement. If its "firm" then its ok, if the fan "free-wheels" or is very easy to move then the clutch needs replacement.

I know of no-way to rebuild a GM fan clutch. Personally I only buy the GM fan clutch because I've had good service from them. I've not had good luck with some of the aftermarket fan clutches.
I normally buy the HD version of the fan clutch if available or the one referenced for cars equipped with A/C.


Originally posted by 22pRE-runner Guy
hey not to take attention away from malibu man but i was just wondering if you can take off the fan clutch/crank-driven fan with out coolant or anything like that spilling out..since its mounted on the same pulley as the water pump? i was looking at installing an electric fan kit also. by the way i picked up a 14 inch zirgo 2600 cfm fan off of ebay for about 70 dollars if anyone else was looking for a place to get one
oh yeah and is it a bad thing to just have a manual switch hooked up instead of a temp-relay switch?
thanks in advance

Yes you can remove all that stuff without leaks. As long as you don't remove a hose or the water pump you should not have any issues with leaks.

Its not a bad thing to have a manual switch but what happens if you forget to turn the fans on? Best to have a automatic switch that works through a relay. You then could also have a manual over-ride where you could turn the fans on at your choosing.


Sorry about my continious reply....I must have one of the settings wrong. I selected the quote & reply button. It looks like all my replys have been included into one response.


Last edited by Elbert; 01-01-2005 at 10:09 AM.
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