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Old 08-07-2004, 07:37 AM
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Unhappy Clutch Fan

Morning

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 ??

Thanks....John

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Old 08-07-2004, 08:25 AM
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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.
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Old 08-07-2004, 08:31 AM
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Ghetto has it right, you need a shroud, otherwise it`s defeating the purpose. There are 2 types of clutch units, thermal and non thermal, a thermal unit freewheels and operates when a certain tempature is reached. A non thermal operates mostly all the time except at freeway speeds. The thermal is the way to go for a street machine, since it freewheels a majority of the time it`s not costing you much power compared to a solid or flex fan.
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Old 08-07-2004, 08:35 AM
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Quote:
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.
You say the fan will engage and allow the fan to operate. When the car is running at idle is the fan blade supposed to be spinning with the engine ? I just checked the center of it and it feels dry

John
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Old 08-07-2004, 10:50 AM
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Another vote for "got to have a fan shroud!"

The fan clutch should be spinning the fan some at idle. It should continue to spin as you bring up the engine speed. Once the air temp coming across the fan clutch gets to a certain point, the coil on the front of the clutch moves and allows the oil inside the clutch to further lock up the clutch.

My experience with fan clutches has been all over the place over the past few years.

I bought a good thermostatic fan clutch for my truck and it works ok, but it seems to always be "on" and spinning the fan hard all the time, but gives up at too low rpm.
I then tried the HD version and it sounds like a Cessna on takeoff but does keep my truck cool all summer, but takes quite a bit of power to run as its "on" all the time. ( It finally unloads after about 3000rpm.)

So now I have a third one. An old half worn out clutch off a Suburban that I run in the winter, then when the heat hits, I put on the HD one and run it 'till fall comes.

Sometimes its a balancing act between good cooling and not sucking 20 horsepower off the engine trying to keep the heat down.

Mark
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Old 08-07-2004, 01:45 PM
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He got it kind of right, clutch fans will ALWAYS be turning with the engine. It's just that when the temp gets high, the clutch tighens a bit and it spins closer to the water pumps RPM. Even a bad clutch fan will spin. And yes you need a shroud.
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Old 08-07-2004, 07:47 PM
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Just to add to what's already been correctly said about clutch fans. One good way of knowing if a thermal clutch fan is in correct operating order is to listen to it on initial start up. It should be engaged after the start up causing the fan to roar until it realizes it's not hot and then allows the fan to quietly freewheel. I've found that when a fan passes this initial test you can be confidently assured that it will engage when the radiator temperature creeps up. It shows that the internal viscous mechanisms are complete and in correct operating order. Rob
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Old 08-08-2004, 09:07 AM
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Clutch Fan

Quote:
Originally posted by 87442lover
He got it kind of right, clutch fans will ALWAYS be turning with the engine. It's just that when the temp gets high, the clutch tighens a bit and it spins closer to the water pumps RPM. Even a bad clutch fan will spin. And yes you need a shroud.
Someone told me there are 2 types of clutch fans, thermal and centrifical. By looking at mine how can I tell which one I have ?

Thanks.......John
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Old 08-08-2004, 01:51 PM
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Clutch Fan

Well guys thanks for all your input on the clutch fan. I got to thinking maybe I should just go with an electic fan kit. I figured by the time I buy a fan shroud , new flex fan , spacer and maybe try to analize whats wrong with my clutch fan since I got it from a salvage yard I would be better off. So any recommendations on what is the best and least expensive fan out there. I have been looking at Be Cool and Hayden fans. I haven't decided wheter to go with the standard fan kit or the kit thats you can set your temp on. But I do have one question how difficult is to install one of these fans ?? Thanks again guys !!

John
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Old 08-08-2004, 04:36 PM
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Re: Clutch Fan

Quote:
Originally posted by malibuman66
Someone told me there are 2 types of clutch fans, thermal and centrifical. By looking at mine how can I tell which one I have ?

Thanks.......John
John, I'm pretty sure that most thermal clutch fans have a by-metallic coil spring on the front face which, I gather, controls the clutch effect according to the radiator temperature.
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Old 08-13-2004, 02:45 AM
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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
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Old 08-13-2004, 11:01 AM
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Electric fans are pretty easy to install. I picked up mine from Summit for about $70. It's a 16", PermaCool (I think). I chose the 16" instead of the 18" b/c it seemed to move more air by looking at the #s. I also picked up the thermostatic Painless wiring kit for around $50 and an on/off/on switch from RadioShack (wired: thermostatic trigger on/off/manuel on). It keeps my 502 cool (around 190 deg.) in stop and go traffic when its 95 deg + outside. I also have a big, two core Griffin aluminum radiator which helps a lot. I didn't notice any difference in temp switching from clutched fan to electric.


On mounting, I don't suggest using the cable/straps/ties through the radiator approach. Over time it will wear holes in the radiator. I ran some 1"x1/8" flat bar through my shroud and bolted the fan to that. I'll put some pictures in the project journal. There are also brackets that mount the fan to the top and bottom of the radiator but that was more $$.

Last edited by 70bird; 08-13-2004 at 11:09 AM.
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Old 08-13-2004, 03:19 PM
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Quote:
Originally posted by 70bird
Electric fans are pretty easy to install. I picked up mine from Summit for about $70. It's a 16", PermaCool (I think). I chose the 16" instead of the 18" b/c it seemed to move more air by looking at the #s. I also picked up the thermostatic Painless wiring kit for around $50 and an on/off/on switch from RadioShack (wired: thermostatic trigger on/off/manuel on). It keeps my 502 cool (around 190 deg.) in stop and go traffic when its 95 deg + outside. I also have a big, two core Griffin aluminum radiator which helps a lot. I didn't notice any difference in temp switching from clutched fan to electric.


On mounting, I don't suggest using the cable/straps/ties through the radiator approach. Over time it will wear holes in the radiator. I ran some 1"x1/8" flat bar through my shroud and bolted the fan to that. I'll put some pictures in the project journal. There are also brackets that mount the fan to the top and bottom of the radiator but that was more $$.
I did a similiar install with my 49 F1 street rod with the same results, never runs more then the set temp of 195 and the dual spall fans never run more the one minute to cool the Griffin Rad down. The stat was not adjustable but is preset at on 195 off about 185*. It did run up to 210* last week going up a 16 percent grade at near 100* outside air up mountains to Big Bear Calif. But cooled right down when the air temp drop some at higher alt. I have encluded a picture of the set up b4 the install in the vehicle. Ed ke6bnl
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Old 08-13-2004, 03:33 PM
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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
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Old 08-13-2004, 04:04 PM
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Quote:
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
If I understand you correctly, you can take the fan and clutch assembly off without any problem, if the center alignment pin is sticking through the pulley snout. What I would do is to remove one stud at a time after removing the clutch and fan and replace it with a suitable bolt and lock tite them then move on to the next. I was able to remove the fan and clutch assembly and replace the clutch and fan with out loosening the belts. Used the tight belts to help hold the pulley while loosening and tightening the nuts on the studs. Ed ke6bnl
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