Whistling Noise Above 25mph

[steinburger56]

Hello, I am new to this forum.
My 2006 Expedition 4x4 has a very difficult problem to diagnose. I am hearing a relatively loud (I'm sensitive to abnormal sounds) whistling noise coming from what I think is the engine/front area of the vehicle. The noise is only present after the vehicle has warmed up, and moving above 25mph. It continues without changing pitch or intensity until the vehicle speed drops to around 15mph. I've read about the intake manifold & idler pulley issues and their tendency to make a racket in cold weather. I just drove the SUV today in 84 degree weather. Same symptoms, wait for warm-up, above 25 noise persists, below 15, it's gone. I shift to neutral while the noise is present, and rev the engine all over. No change in pitch or intensity. I apply the brakes, parking brake too, no change. 4x4 engage, dis-engage, no change. I'm pulling out my hair now. The noise can best be described as sort of a combination of a high pitch brake squeal mixed with a wind whistle. I'm considering inducing the sound and shutting off the engine in neutral to rule out a vacuum leak of some sort, but I'm terrified of blowing a cat, or freaking out the RSC/ABS/Trac Ctrl system. Anyone have any ideas? Oh, the vehicle is bone, soccer-mom stock. Regular maintenance, 99K miles. Any help would be greatly appreciated.

Brian

P.s. A/C, HVAC on or off have no effect. Stereo on/off same thing.

 

[toms89]

I think I would rule out vacuum leak or engine if it does not occur below 25 mph or with change in throttle.

Brakes can certainly squeal. Bearings?? Possibly 4wd components or IWE's?? Windows up or down does it make a difference. Assume not but if so maybe weather stripping not sealing??

 

[king.Brad]

I'm almost 100% sure it's your idler pulley, I just had to replace mine not long ago and it did the same thing you are describing. It drove my wife nuts, she thought it was a window cracked or the bumper was cracked because it made a whistling sound every time we got passed 25mpr. I told her it was the idler pully, I replaced it and problem solved.

 

[steinburger56]

Update:

Drove the SUV today on a quiet country backroad. got it up to about 35mph on a gentle downgrade and shifted to neutral. Shut down the engine and coasted to a stop. The noise is present and behaves exactly as before. With my entire torso out the drivers side window, I can't pinpoint exactly where it's coming from, even with the engine OFF. Next I took it back home and jacked up the rear end, blocked the front wheels and wound it up to about 30mph. No sound, but definitely triggered an ABS light... (it cleared on the next ABS self test; @+12mph, all four wheels turning) Now I think I'm closing in on something with the front driveline. Everything is always moving with these vehicles, as there is no hub lock/unlock function. Maybe a CV joint? There are four of those, or perhaps a U-joint on the front driveshaft... I'll pull that out tomorrow and test drive again. I'm also not familiar with what sort of sound these "sealed for life" wheel hubs make when they fail. I'm about to take the vehicle on an 800mi trip, half of which I'll be towing a 5500lb boat. Nervous doesn't begin to describe where I'm at. Surely someone has seen this before...

 

[Mediamonkey11]

Bearings nor Ujoints will make a Whistling noise, or I've never heard them make one. I'm thinking brakes... Any chance you an make a recording?

 

[RAWPWR]

have you tried to just rev up in the driveway to see if you can hear it in the car and or hear it at the front while someone else is revving it?

 

[toms89]

I am thinking brakes are the most likely as well.

Maybe someone installed a deer whistle or similar as a joke...

You have not recently installed something that can disturb the aerodynamics or possibly interrupt the air flow have you??

 

[stamp11127]

Man all you Yankees go about things the hard way. If you were here in the red neck south you'd get Bubba to ride along side in his truck and give a listen to as yours went whistling away, that way youd have an ideear of where it is comin from.

Mispellins are deliberate

 

[steinburger56]

Outstanding replies, I especially enjoyed stamp11127's. I made two recordings, but it appears this forum only supports image & text files on it's list of accepted uploads. As I mentioned, the noise does not occur until the engine has reached full operating temperature, which I think is coincidental because the noise persisted when I shut the engine off at 35mph. I would reasonably assume that fact should eliminate aerodynamic issues, because when I leave the driveway and drive for a few miles, no noise. As far as the brakes go, they are fairly new with a few thousand miles on them. The noise is unaffected by braking, braking pressure, parking brake, no brake... doesn't seem to matter at all. I do have one concern though... When I changed the brake pads/rotors, I had to beat one of the front rotors off the hub with a block of wood and a pretty good sized mallet. No amount of heat or penetrating oil would do it. Is it possible I could have damaged the hub? They're very expensive so I'd hate to just throw some new ones on to test that theory. Oh, and hanging off the running boards at speed has certainly crossed my mind... I just think I should probably wear a helmet and that would make it hard to hear!

 

[stamp11127]

You can upload the video to youtube and post a link. Unless you can move mountains you didn't damage the hub with a mallet. Now a sledge hammer directly on the hub - different story.

If your going to hang off the running boards at speed, you need to move to
Alabama. That is genius over there....