Clutch Fan - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**53burb** · 04-09-2005, 11:07 PM

I changed my waterpump the other day and also changed out my flexfan the PO had in it. Anyways, the engine is running hot now. I compared the clutch that I had to a brand new one, and it seemed ok. Tomorrow I am going to put the flexfan back on to see if that takes care of the problem. When I replace the clutch, what part# or model do you guys recommend? The one I was using is off an '85 Chevy 1/2 ton 4x4 w/a 350. I wanted one that was a little shorter if possible. With it installed, the fan only comes out of the shroud about an inch or less.

CHEVIBUBBA · 04-10-2005, 12:04 AM

let me see if i understand;
the po had a flex fan on your truck
you removed it when you changed the water pump & installed a clutch fan.
now it runs hot.
correct?
there are actually two different types of clytch fans;
one slips all the time & one will lock up when it gets hot but kinda freewheels when not needed.
you want the one that will lock up when the engine gets hot.
it has a coiled spring looking thing on the front center of the clutch.
are you certain the water pump is the correct rotation for your engine?
did you change the thermostat?you need to.
please define "hot".
is it climbing out of sight or does it get to like 230 & hang there?
you should have a clutchfan or electric if possible.flexfans kill power/fuel mileage.

**53burb** · 04-10-2005, 12:35 AM

It does have the spring on the front of it. I didn't c/o the thermostat. It seems to be able to freewheel all the time. A friend gave me this clutch about 5 years ago from his truck when he switched to a TPI. I compared it to a new one, and it seemed ok. As for temp, I am using the stock gauge, and it is in the red after only about 3-5 miles. Previously, the temp sender was on the w/p. I moved it to the water outlet. I couldn't get the fitting off of the drivers side head to use that port.

86k10 · 04-10-2005, 12:49 AM

There is a way to check the clutch with the spring. You'll see the end of it is in a slot, take it out of the slot and back it up oh a quarter turn or so and after you start it and rev it up for a bit it should lock up and stay that way until you put the spring back in it's slot. If it doesn't then the clutch has lost it's fluid and is no good.

**53burb** · 04-10-2005, 01:22 AM

Thanks, I will try that tomorrow....

**53burb** · 04-10-2005, 01:23 AM

Forgot to ask, it should be locked up after I shut the engine down right???

**Stocker** · 04-10-2005, 09:59 AM

When cold, it should feel gooey, kinda like it's running in molasses. It should not spin freely. I've never checked to see if it actually feels "locked up" when hot. If yours has the 2-piece sandwich design (front & rears halves bolt together), you can take it apart and add silicon fluid and it's good to go. I did that with mine many years back and it's still good. Only place I found the fluid was at a Toyota dealer. Hope you get it fixed (or replaced) - a good clutch fan is far better than a flex fan.

tmcgrawlookalike · 04-10-2005, 10:41 AM

why not go to the parts store and get a new one/ask for a heavy duty one,and say it is with a/c.i wouldn`t take a chance on one that#1-is used#2-been sitting for 5 years.

tmcgrawlookalike · 04-10-2005, 10:46 AM

what i have been told is the correct location of fan in shroud is no further than 1/2-3/4 into shroud,and vice-versa on outside.anyone else on this?

**Stocker** · 04-10-2005, 11:58 AM

Quote:

Originally Posted by tmcgrawlookalike

what i have been told is the correct location of fan in shroud is no further than 1/2-3/4 into shroud,and vice-versa on outside.anyone else on this?

Sounds about right, been discussed here before. My stock fan sits roughly half in & half out of the shroud.

flip66 · 04-11-2005, 02:46 PM

Probably not it but make sure the pump is turning the right way. There is a pump for the 350s that turns in the reveres direction not sure what years it was for.

**53burb** · 04-11-2005, 03:28 PM

I put the flexfan back on. I compared it to another brand new clutch and the new clutch was alot tighter. The overheating problem was from the thermostat. It looked fine when I replaced the water outlet the other day, plus it is less than a year old and worked before all this happened. I blew the head gasket with it constantly heating up and me driving it like that, but I had no choice. The engine was on its way out anyways. It runs fine, but how long will it last llike this???

04-10-2005, 12:49 AM	#4
86k10 Registered User Join Date: Feb 2003 Location: Bertrand, Nebraska Posts: 355	There is a way to check the clutch with the spring. You'll see the end of it is in a slot, take it out of the slot and back it up oh a quarter turn or so and after you start it and rev it up for a bit it should lock up and stay that way until you put the spring back in it's slot. If it doesn't then the clutch has lost it's fluid and is no good. __________________ 98 Neon 97 Grand Prix GT 02 Grand Prix 40th Anniv. 86 GMC 5.0 77 Olds 98 6.6 REAL AMERICANS, DRIVE AMERICAN

04-10-2005, 09:59 AM	#7
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,728	When cold, it should feel gooey, kinda like it's running in molasses. It should not spin freely. I've never checked to see if it actually feels "locked up" when hot. If yours has the 2-piece sandwich design (front & rears halves bolt together), you can take it apart and add silicon fluid and it's good to go. I did that with mine many years back and it's still good. Only place I found the fluid was at a Toyota dealer. Hope you get it fixed (or replaced) - a good clutch fan is far better than a flex fan. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

04-11-2005, 02:46 PM	#11
flip66 Registered User Join Date: Jan 2004 Location: Garland TX Dallas area Posts: 658	Probably not it but make sure the pump is turning the right way. There is a pump for the 350s that turns in the reveres direction not sure what years it was for. __________________ 1998 Pontiac Grad Prix GTP 1969 C10 396 TH400 3.08 posi

04-09-2005, 11:07 PM	#1
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,010	Clutch Fan I changed my waterpump the other day and also changed out my flexfan the PO had in it. Anyways, the engine is running hot now. I compared the clutch that I had to a brand new one, and it seemed ok. Tomorrow I am going to put the flexfan back on to see if that takes care of the problem. When I replace the clutch, what part# or model do you guys recommend? The one I was using is off an '85 Chevy 1/2 ton 4x4 w/a 350. I wanted one that was a little shorter if possible. With it installed, the fan only comes out of the shroud about an inch or less.

04-10-2005, 12:04 AM	#2
CHEVIBUBBA got boost? Join Date: Mar 2005 Posts: 123	let me see if i understand; the po had a flex fan on your truck you removed it when you changed the water pump & installed a clutch fan. now it runs hot. correct? there are actually two different types of clytch fans; one slips all the time & one will lock up when it gets hot but kinda freewheels when not needed. you want the one that will lock up when the engine gets hot. it has a coiled spring looking thing on the front center of the clutch. are you certain the water pump is the correct rotation for your engine? did you change the thermostat?you need to. please define "hot". is it climbing out of sight or does it get to like 230 & hang there? you should have a clutchfan or electric if possible.flexfans kill power/fuel mileage. __________________ '70 chevy lwb w/'67 hood. 357 s.b.c. built, 4l60 w/vigilante lockup high stall converter, edelbrock pro-flo,brodix heads,comp cams rollerized w/ belt drive, one piece d-shaft, yada, yada, yada..... '82 honda v45 sabre"the black"

04-10-2005, 12:35 AM	#3
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,010	It does have the spring on the front of it. I didn't c/o the thermostat. It seems to be able to freewheel all the time. A friend gave me this clutch about 5 years ago from his truck when he switched to a TPI. I compared it to a new one, and it seemed ok. As for temp, I am using the stock gauge, and it is in the red after only about 3-5 miles. Previously, the temp sender was on the w/p. I moved it to the water outlet. I couldn't get the fitting off of the drivers side head to use that port.

04-10-2005, 01:22 AM	#5
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,010	Thanks, I will try that tomorrow....

04-10-2005, 01:23 AM	#6
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,010	Forgot to ask, it should be locked up after I shut the engine down right???

04-10-2005, 10:41 AM	#8
tmcgrawlookalike Registered User Join Date: Jun 2004 Location: warr acres,oklahoma Posts: 650	why not go to the parts store and get a new one/ask for a heavy duty one,and say it is with a/c.i wouldn`t take a chance on one that#1-is used#2-been sitting for 5 years.

04-10-2005, 10:46 AM	#9
tmcgrawlookalike Registered User Join Date: Jun 2004 Location: warr acres,oklahoma Posts: 650	what i have been told is the correct location of fan in shroud is no further than 1/2-3/4 into shroud,and vice-versa on outside.anyone else on this?

04-11-2005, 03:28 PM	#12
53burb Senior Member Join Date: May 2004 Location: Queen Creek, AZ Posts: 1,010	I put the flexfan back on. I compared it to another brand new clutch and the new clutch was alot tighter. The overheating problem was from the thermostat. It looked fine when I replaced the water outlet the other day, plus it is less than a year old and worked before all this happened. I blew the head gasket with it constantly heating up and me driving it like that, but I had no choice. The engine was on its way out anyways. It runs fine, but how long will it last llike this???



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