Possible belt slip, high pitch shrill at moderate to high throttle

[jdraker62]

I have a 2006 Ram 2500 with 140k miles on it. I have recently gone through a series of upgrades but have noticed one thing. If the AC is on and the fan clutch is engaged there is a high shrill or buzz at moderate to high throttle. If the fan spins down and the ac is on it doesn't exist. Now everything is new except the alternator. Two years ago my new power steering pump lost its pulley sending it through the system shearing off the tensioner and cutting some wires. This in itself is a long story that I won't go into and I will never use that shop again. Fast forward to today. I just replaced the fan clutch again (#3) along with the AC compressor last weekend. The old one was weeping oil and I thought that is what was causing the noise was a locked up compressor. All that has been cleaned up. So now is my belt tensioner bad, do I have a bad fan clutch? Any help would be appreciated.

Joel

 

[NIsaacs]

Check for a high pressure boost leak.

Nick

 

[CJ8Rockcrawler]

I had a similar issue this summer and found that my relatively new belt had glazed and would squeal under high load. I too thought the boost leak and tightened all the boots, to no avail. I switched out the belt with my spare from the boonie box and problem solved. Either issue is the likely culprit and thankfully they are easy and inexpensive fixes.

 

[cerberusiam]

Change the serpentine belt first. it is the usual culprit.

 

[thintze]

Check your exhaust manifold. If you have a stock or one piece manifold you may have broken a stud or two. The gasket acts like a harmonica when the exhaust escapes under load. Sounds crazy but I replaced my turbo thinking it was losing a bearing and it was just broken manifold studs.

 

[jdraker62]

I will change the belt again to see if it goes away. I have already tightened all the boost hoses along with the exhaust. I still have the factory exhaust manifold. That will be replaced in the spring when the twins come. It only does this with the ac on cold fan clutch engaged and accelerating moderate to heavy. It won’t do it if I turn off the ac and floor it or at any throttle setting. Also it doesn’t do it if the fan clutch disengages.

 

[WalterJ]

Had similar annoying noise, & solved it by installing an old spare. The 2yr old premium belt was too stiff and we surmise its back was slipping on the idler pulley. This premium would have lasted 100yrs., but too stiff here. Hmmm, that reminds me, I have no spare!

 

[The patriot]

Check the tensioner and the idler pulley bearing.

 

[Tuesdak]

Can you clear up if it's high throttle or high RPM? Perhaps both? IMO High RPM would be the belt where high throttle is a boost/exhaust leak as others suggested. I had a hose from the turbo to the intercooler pipe looking bad in the center , but, didn't solve my issue. You have the plastic intercooler so you may want to check it for leaks as well.

Curious as to what belt you are running? Also asked similar and may not apply to you as the fan RPM was audibly changing at a steady high engine RPM for me: https://www.turbodieselregister.com...ws-down-and-speeds-up-like-something-slipping

 

[cerberusiam]

A 2006 should not have a plastic end tank CAC, that was only early 2005 models.

 

[seafish]

Yup, even my mid yeR 2005 HAD

A 2006 should not have a plastic end tank CAC, that was only early 2005 models.

Yup....even my April 2005 had aluminum end caps on the intercooler.