Mysterious high pitched squeal from underneath under load

[DCSVT1]

I’ve been hearing a high pitched squeal coming from underneath while under hard acceleration. (2010 6.2) Typically I hear this in 2nd /3rd when the RPM gets up over 3k. I brought it to the dealer and they said it was the belt, so I changed the belt but the sound remains. Worth mentioning that I have Roush CAI and exhaust so it’s fairly loud but you can clearly hear this. Currently the truck is back at the dealer, they say they can hear it but have no idea what’s causing it and it’s hard to track down because it only happens while driving it. Suggestions??

 

[Sozzy12]

Bad tensioner?

 

[Dane]

Sounds like one of the pulleys (tensioner or one of the accessory drives).

You said it's over 3K RPM, do you hear the squeal vary with RPM? What if you just rev the motor in neutral to that RPM?

 

[DCSVT1]

Sounds like one of the pulleys (tensioner or one of the accessory drives).

You said it's over 3K RPM, do you hear the squeal vary with RPM? What if you just rev the motor in neutral to that RPM?

I had the tensioner replaced as well as the AC compressor. It did it before and after. The noise starts at about 3200 and is a constant squeal/whistle. If you gradually get it up there it's less noticeable than a jackrabbit start with hard acceleration up to/over 3500. Very noticeable when you do that. Not sure when it stops as far as the RPM. Don't think I get it up over 4k often, of if I do the Roush exhaust (basically open pipe) eventually drowns it out...or I let off because I'm going to plaid!
The rev limiter on it wont allow you to go over 2k while in park...tried. Can only get it to do it in drive.

 

[Dane]

Power steering? Anything different while turning sharply?

 

[Jr24]

Does it appear to have any noticeable loss of power or sluggishness?

 

[DCSVT1]

No loss in power and no idea if turning makes a difference. This would be under load in a straight line...light turns green, mash the gas, RPMs go up, whistle from underneath @3200. Chances are if I was going to turn I'd let off & RPMs would go down = no whistle.
I will add that every now and then it will make a clunk/thud shifting from 2nd to 3rd or 3rd to 4th and sometimes a thud/clunk halfway through a gear. Again it's more noticeable under hard acceleration or while towing. I reported all this to Ford and suggested they were related and said I thought it was the trans making the noise.

In a somewhat related issue, I'm not real pleased with my local Ford dealers and have had repeated issues with a couple of them. This time; brought it there last Wednesday for "the works" and told them about this noise. Said I was leaving it there all day so maybe they could take a look. Called at the end of the day, was told they heard the noise, couldn't figure out the source and wanted to keep it for another day. Went there @ 5 the next day and the truck is sitting outside. Went in, was told they could not figure it out and had a call into Ford corp for help. Took the truck and said I would bring it back the following week as we were headed to New England for the weekend. Got a few miles down the road and realized that not only had they NOT fixed the problem, but also had NOT changed the oil or rotated the tires. WTF!!! So I had to drive 600 miles on what was already an overdue oil change. Not to mention all the "test drives" they did. Frustrating.

 

[Buzzard2]

I have the same issue on my 2012, sure would like to be able to figure this out and fix it.

 

[Sharkus29]

I’ve been hearing a high pitched squeal coming from underneath while under hard acceleration. (2010 6.2) Typically I hear this in 2nd /3rd when the RPM gets up over 3k. I brought it to the dealer and they said it was the belt, so I changed the belt but the sound remains. Worth mentioning that I have Roush CAI and exhaust so it’s fairly loud but you can clearly hear this. Currently the truck is back at the dealer, they say they can hear it but have no idea what’s causing it and it’s hard to track down because it only happens while driving it. Suggestions??

Its not the whistle from your CAI is it? Some intakes are loud when sucking in air, especially at a certain rpm

 

[Buzzard2]

The high pitched whine happens just as the gears are shifting up if your real easy on the pedal only does it from 4 into 5th and 5th to 6th gear if your heavily accelerating happens thru most gears. Never hear it when tyranny is down shifting.