Fan shroud install Q

[GMCjunkie]

I have not had a fan shroud in years. I had electric fans, and went back stock. What is the process for installing the shroud? Do I need to remove the radiator? The shroud is too thick to just set down in place. Are there any tricks or tips I should know about??

Thanks so much!!!
junk

[WIDESIDE72]

1. Get rid of the flex fan before it explodes and ruins the radiator, hood and possibly you. The aluminum work hardens over time from flexing and will fail eventually. Before that it will shred your hands and arms if you try to install a shroud.

2. The shroud can then be installed

3. Then you can install a factory style clutch fan. You can come across them on the parts board or some places like LMC sell new ones.

[Dunenutt]

^^^^^^^^^ What he said!

[OregonNed]

Thanks for that tip. I have one of those fans too

[Stocker]

Yes, definitely toss the flex fan. If your truck is like mine, there are clips (two, I think) at the bottom of the radiator for the shroud to slip down into. Two bolts attach it at the top. Bolt up a good thermal clutch fan and you're set. The fan should be centered about halfway in the shroud opening. An 18" fan seems to be a common size, and more blades (7 is good) will provide all the cooling you need.

[leftybass209]

To install the fan shroud I removed the fan, then held the fan and shroud as I lowered them into position. You can let the shroud dangle as you reinstall the fan, then mount the shroud. 2 people makes it easier.

[GMCjunkie]

http://www.lmctruck.com/icatalog/cb/full.aspx?Page=63

Not sure how to post a link, hope this will come up. Is this what yall are talking about?

And thank you for your help!

[GMCjunkie]

What exactly is the function of the "fan clutch" anyways?

[WIDESIDE72]

The lmc link is in fact correct. The clutch is thermally activated. When it is hot it locks up to pull air through the radiator. When it is cool it freewheels, freeing up horsepower and fuel.

[GMCjunkie]

So it has to be wired in?

[kcsa75]

Originally Posted by GMCjunkie

So it has to be wired in?

No wiring. It's a centrifugal clutch. The faster the motor runs, the freer the fans spins. The idea being if you're sitting at idle the fans needs to pull more air. As you drive, the faster you go, the more air you're going to get through the radiator and over the engine so the fan doesn't have to work as hard. At highway speeds, the fan pretty much just along for the ride.

[Stocker]

They also contain thermally sensitive silicone fluid. Hot enough and the fluid thickens to engage the fan so it pulls more air. Here's a cutaway pic and a link to more info.



http://www.aa1car.com/library/cooling_fan_clutch.htm

[GMCjunkie]

OMG you guys are amazing, what would I do without you?? Thanks so much for the information!!!!! Comparing prices now.....

[71swb4x4]

Shrouds are different too, 6 cyl, V8 2wd and V8 4wd I think. Not sure if there was a difference in big block shrouds.
The 4wd shroud is deeper since the engine sits back a little to clear the front differential. Sounds like you have the 4wd shroud since you mentioned how thick it is.

[GMCjunkie]

[QUOTE Sounds like you have the 4wd shroud since you mentioned how thick it is.[/QUOTE]

I do, and where the heck have YOU been? :p

[GMCjunkie]

Ok, heres another question, the ad in LMC does not show a fan blade for a sb 350, is it the same as for the other engine sizes?
Also, do I need the spacer thingie that my flex fan is attached to to install the stock blade and clutch? Do I need anything else besides the fan and the clutch to install?

Thanks so much!!
JUNK

[71swb4x4]

I apologize if you already know this, but you should be able to get the fan and the clutch at a local parts store. Maybe you are just using the LMC catalog for the diagram.

[Stocker]

Originally Posted by GMCjunkie

Also, do I need the spacer thingie that my flex fan is attached to to install the stock blade and clutch?

Nope.

Do I need anything else besides the fan and the clutch to install?

Just 4 bolts (maybe lockwashers, I can't recall).

[GMCjunkie]

I tried through our local store, they could get the clutch but not the blade. I may call Napa, they also offer a military discount.

Thank you Stocker!!

[kev2809]

i just installed mine last week. i too had the flex fan and read the horror stories so i pulled it and bought a clutch fan off the board.

pull the fan, drop the shroud in, then hang the shroud up towards the water neck area and you can put the fan on from there. will be hard to maneuver by yourself and get the bolts in, but i did it by myself. i went and got water pump studs instead of using the regular bolts, the studs made it so much easier to get in.

after you get the fan on, you can drop the shroud all the way in and start bolting it down. 1 thing to check though is to make sure your top radiator hose and outlet on the radiator clear the shroud hole. i got mine from LMC and it fit good, except i had to enlarge the hose cutout on the shroud to fit.

[WIDESIDE72]

I have never found the fan blade part in parts stores. However, they aill have the clutch and a hardware kit that consists of four studs that are fine thread on one end and coarse on the other as well as four nuts and lock washers. I believe i have found them in the "HELP" section.

[WIDESIDE72]

Im not sure why LMC doesnt lost a fan for the 350. I thought only a/c trucks had a different fan. Do all 350's have a different fan?

Imo, i would post a wtb on the parts forum. You might luck out like i did and get a good clean functional fan and clutch for $50 shipped.

[Stocker]

If all else fails, check local junkyards for an OEM fan. As long as the diameter & bolt patterns match (and it's not from a serpentine setup) you'll be good to go.

[kev2809]

Originally Posted by WIDESIDE72

You might luck out like i did and get a good clean functional fan and clutch for $50 shipped.

id check that first, i got mine for 45 shipped

[seattle gmc]

Originally Posted by Stocker

If all else fails, check local junkyards for an OEM fan. As long as the diameter & bolt patterns match (and it's not from a serpentine setup) you'll be good to go.

I see alot of clutch fans on the 70's square bodys. Do you think that they will fit?? If so is the clutch sill good??? I have passed many in the junk yards and allways have thought about picking one up, but haven't yet. I have the regular four blade fan in my truck, and im thinking about upgrading.