Switching from flex fan to OEM steel fan.

[Mullins72Custom]

Over the past several months I've had an issue with truck over-heating while ideling over 10 mn ect. I HAD a flex-fan without a shroud so I decided to install a shroud. It didn't help as wished, so I swapped my flex fan out for my friends OEM steel fan/clutch. Instillation went fine, and my over heating problem was solved! BUTTT as I drive around 40 mph or > it squels like a lost pig. Belts are tight, fan is attached tight. I used some dove soap to coat the belt, but the squelling continues! Any advice? Is the new fan throwing something off?

[MagmaJct]

When the engine is not running, can you turn the fan by hand? You should be able to. If you can't, the clutch is seized causing the fan to be spun too fast. Faster than the belt can handle.

Is it a thermo clutch or RPM clutch?

[Mullins72Custom]

Yes, I can spin the fan by hand with the engine is off. I'm not positive if it is thermo or RPM clutch. Although when I start off it will squel when shifting gears, then settle down till 40 mph.

[Stocker]

My fan clutch contains a thermal silicon fluid (maybe they all do?). If some of it has leaked out, the unit may be dry enough inside to squeal. If your front & rear halves bolt together (like mine), you can take it apart and add more fluid. Only place I found fluid was at a Toyota dealer. Can't remember if it took one small vial or two, also can't remember if mine was squealing or just locked up. This happened many years ago, and it's been good ever since.

[Coley]

My take on this:
.......having the belt(s) tight, does not always 'forgive' an old 'polished' belt or a possibly the wrong belt (width/depth) on there.
If you can, find another used belt, mount it up and try it. If you see an improvement from what you have now...then go for a new, correct belt.
Also, as mentioned above, if the belt that is on there is not exactly the right width/type fan belt and you can't vouch for the history of where it came from and how long its been on (substituted at some point in time?)....that could be (partially or completely?) causing this.
Good Luck, keep us posted.
Coley

[screamin_c10]

Believe it or not a standard rotation fan on a reverse rotation water pump (or viceversa) will do the same thing. It'll cool fine when idling as the fan is pushing air through the radiator out the grille, but when you get the vehicle movin the air coming in through the grille will fight the fan and cause it to overcome the belt and squeal... Saw a guy do this on a serpentine swap. Took forever for him to figure it out... Moral of the story, make sure your fan is the correct one for the pumps rotation (serpentine / non serpentine)

[Mullins72Custom]

Appreciate the advice. I'll look to adjust the belt or maybe replace, to see how it responds. I'll keep my eyes out for another fan to pop on, and see if that is the victim. I failed to say in the opening post, but it DIDN"T squeal any with my old flex fan installed.

[Stocker]

Originally Posted by Mullins72Custom

it DIDN"T squeal any with my old flex fan installed.

A fully engaged clutch fan will be a lot harder to spin at speed than a flex fan (because the blades pull so much more air), so the extra effort *might* cause a belt to squeal even though it didn't with a flex fan.