Fan belt squealing

[Roysbigtoys]

I have a '09 Pete 386 with an ISX 485. With the engine rpm over 1400, the fan belt squeals. It really does it with the AC on. So far I have replaced the belt tensioner and a new fan belt......they helped a little.
Once I put those parts on I started the engine and ran it over 1400 rpm for a minute, killed the engine and felt the pulleys. The crankshaft pulley is the one slipping as it was the warmest or should I say the hottest.
Do I replace the crank pulley next? Is there anything else that could be causing the belt to slip?
The truck has 519000 miles and 19000 hrs. The harmonic balancer has not been changed. I think I remembered in the old forum some talk about if the balancer was bad it would sometimes cause belt problems.
Thanks in advance.

[Mr Hagg]

What kind of belt did you put on? I had a truck in here a few months back that did that. I cleaned ALL pulleys changed tensioner still same issue. Then I got a gaterback belt and problem gone. But make sure all pulleys are clean.

[Nilao]

If it were me I would take the belts off the pulleys and spin all the components by hand. I'd be feeling and listening for grinding or resistance in the bearings. Watched a roadside service guy try to start a truck in the truck stop for over an hour. Walked over and asked the driver what was wrong. Long story short, it would not turn over. Mechanic was thinking hydro lock. I looked it over for 3 minutes and noticed the a/c clutch pulley was overheated as the plastic insulation has sagging off the bottom. Once the wanna be tech removed the a/c belt it fired right up.

[Roysbigtoys]

Well here is an update. I cleaned all the pulleys and checked to see that they all turned freely. Taking Mr Hagg's advise, I ordered a Gatorback belt. After waiting several days for " over night shipping" from Summit Racing, I canceled my order. I then found the belt on Amazon for a better price and free shipping....."thanks" to my wife for being such a frequent shopper. In the mean time I changed the harmonic balancer and the bottom pulley, put the slightly used oem belt on ( at this point I did not have the new Gatorback belt ) and the squealing stopped.
The pulley did not look worn, but apparently it was enough to slip. I haven't put the new belt on yet, but it looks like a beast and had really good reviews. I will probably run the oem for a while then put the new one on.
Thank you Rawze for this site and for everyone who contributes to it.

[Brock]

When I changed my belt and tensioners I called international and they wanted $120 fir my serpentine belt and 250 for tensioner. I said screw that and called my local part source (kinda like a pep boys) and got myself the continental version of the gatorback for 35 bucks and the tensioner for 160.

Continental bought out good year for everything not tire so now gatorbacks are contitech...I went to continentals website but they list too many part numbers for how many belts and pulleys there are. It's like navigating a maze drink and blindfolded.

Damn stealerships love over charging!!

[Brock]

Sorry, I shouldn't say "everything not tire" cause I know stemco bought their airbags. conti has belts and pulleys and such.