Really strange new issue... Help?

[Jeff532003]

UPDATED WITH VIDEO! SEE BELOW FOR LINK!

Okay so I promise I'm not going insane lol. This morning on my way home from work I started the truck and noticed the typical ford power steering whine was a little more noticeable. Chalked it up to having gotten down to 20 degrees last night as it normally does this when the fluid is really cold. Well I'm pulling out of the driveway and I make the slightest correction with the wheel and it sounds like someone took a megaphone and hit a tuning fork against while pointed right at me. Only lasted a second maybe two. Freaked me out so I shut the radio off to listen closer. Pull out on the road and it does it again also making a slight correction. Now I'm thinking its power steering issue but I've never heard a noise like this. I try turning the wheel more aggressively as I go down the road and can't get it to replicate. About 2 min later it does it again when I slightly correct with the wheel but less noticeably this time. A min after that and the truck is up to operating temp and it doesn't happen again for the rest of my ride home. Get up this afternoon and drive down to pick up my kids at the end of the driveway (over 1/4 mile) and nothing. Leave for work around 630 and it seems fine. I get about a mile away and it does it again as I slightly correct the wheel. Does it one more time about 40 seconds later and then that's it. The rest of the drive to work is fine. Called and asked my father who's been an ASE master tech for 40 years and he's never heard of anything like it and says he'll have to try and hear it when I come down on Saturday. So in the mean time I'm going out on a limb and seeing if any of you have any idea what it might be?
There's no metal on metal sound, no squeal or whining noise. Just this really loud odd harmonic sound. I'm thinking it has something to do with the power steering but honestly I have no clue. Thanks in advance for any ideas.

 

[stamp11127]

Check pwr steering fluid level.

 

[Jeff532003]

Check pwr steering fluid level.

Perfectly at the full line. Doesn't smell burnt.

 

[Jeff532003]

So I went out on break at work and went for a ride with my video camera on to see if I could get to happen while filming. I noticed it was pulling to the right so I got out and looked and the drivers side tire was half flat. Stopped at the gas station and it was below 10 psi. Filled it back up to 37 and it's driving straight as an arrow. Hopefully the one low tire was causing a vibration that caused something in the front end to ring like that and there all it was.

 

[ArtGamer60]

maybe something loose ? caliper , rotor , etc ...

 

[Jeff532003]

maybe something loose ? caliper , rotor , etc ...

Just did the brakes a little over a week ago. Snugged and lubed everything up good but if it keeps up I'll double check. Pedal feels perfect though. Nice and smooth and no vibrations when I apply the brake.
I'm really hoping it was just that tire being really low on air. I'll have to inspect it for a nail when it's light out.

 

[Jeff532003]

Odd harmonic noise 98 ford expedition 4.6 - YouTube

Sooooo it was worse than ever this morning. Managed to capture the sound on video. Any ideas at all? If you don't want to watch the whole thing it is at it's worst at around 2 minutes in. I could almost faintly make out a noise from the passenger side when I popped the hood but its hard to tell over the fan. I'm beginning to think it might have something to do with the new belt tensioner I installed 2 weeks ago. Did not notice the noise until yesterday morning though.

 

[Lightnig]

That is a wierd one.

At first, I just thought the background noise I was hearing was a bad idler pulley. I had one go bad on me a few years ago and that's what it sounded like.

But that wasn't the sound you were talking about, (for those that are looking, the best example of it is at 2:02 in the video). That one I have no idea. Definately some type of sympathetic vibration.

But to me, that almost sounded like it was in cabin. I would think that if it was belt related that it would be more muffled than that.

 

[Jeff532003]

It does sound like its being projected right into the cabin but if I roll the window down I can hear it coming from under the hood. I suppose I'm going to have to try and replicate it while I'm under the hood listening. So far I've only got it to happen under load.

 

[Stoned06]

Do you have an aftermarket CAI? Sometimes you can get a whistle from them, especially the K&N ones. Other than that, you got me.

 

[1997SCEBFEX]

i'm sure you checked all your pulleys and serpentine belt routing? it doesn't seem like a belt squeal, but hard to tell from where I sit. is your belt excessively tight with the new tensioner?
it seems to occur from your video in the 2500-3000 rpm range?
any other rarities?

PanHandler.

late minute thought: when one of my supercharger idler pulleys was starting to 'puke' its bearing, it gave off a similar noise. Perhaps alternator or p.s. pump?

 

[Jeff532003]

Props to Panhandler and Lightning for calling it. I was fairly certain it was a something in the belt drive but I've never heard anything fail so spectacularly. That harmonic noise so was loud when it hit you could feel it resonate through you.
So anyway I'm 99.9% certain it's fixed. Tomorrow morning on cold start will fully confirm. I finally have a night off from work so I got up this afternoon and went to work on it. This morning I was fairly certain I'd pinned it down to passenger side front which left tensioner idler pully and AC compressor but any noise I heard was so faint I wasn't certain. Fired it up this afternoon and definitely heard a faint intermittent little squeak randomly as it idled. I'd already spun the idler and it felt fine attached but I knew it wasn't AC compressor as no change when I turned it on and engaged the clutch. Figured it had to be idler so I pulled it up and sure enough spinning it in my hand, the bearings felt like someone dumped sand in there. Trip to auto zone, changed it in their parking lot and it seems all good now. Nice and quiet and no noise detectable. I'll update when I'm certain it's fixed but I'm fairly sure now. Thanks so much for all your replies.

 

[Lightnig]

Good to hear.

Let us know after you've lived with it a few days and are certain it's fixed

 

[1997SCEBFEX]

Good news for sure & hope you both diagnosed/fixed it up.
Nice feeling inside when you can accomplish things on your own & glad we were able to virtually help.

PanHandler.

 

[Jeff532003]

Just wanted to update this in case anyone else has this issue. This was one of those things were fixing one issue created another. Replacing the broken belt tensioner allowed my belt to actually run tight instead of half slipping like it was when I got it. Replacing that started the squeal. I noticed a squeak coming from the idler pully so I thought there was a good chance that was what was causing the noise. I replaced it and for reasons unknown to me it didn't squeal for about a week but then started up again. Using my stethoscope I still could not definitively hear the squeal as it would not happen unless conditions seemed to be perfect. I did however hear what sounded like a lot of grinding bearing noise coming from the alternator. I tried to convince myself it was just the brushes spinning but it just didn't sound like that so I decided I'd replace it and if the new one had the same noise is just return it. Well low and behold I hooked up my brand new, not reman, alternator up and it was quiet as could be with the stethoscope. Over three weeks now and the squeak is fully cured and a few other broken parts where replaced so no lose there either.
So if you ever experience this awful noise in your truck check the alternator. I'd never of guessed it could make that god awful noise so loud in the cab of the truck but resonating metal acting as an amplifier is confusing like that.

 

[Lightnig]

Good news, glad to hear that you got the issue fully resolved.

And thanks for taking the time to give us the update

 

[uscgmac]

I know this is an old post but I'm glad I found it. I have the same exact noise to a tee. It is so exact that I don't even have to try and recreate the noise. It's as if I'm driving my own truck. This started a couple days ago when it got cold out for the first time this year and only does it intermittently. I'm figuring that the pully is in the beginning stages of going because it just started doing it and it's not as frequent or as loud as yours but I'm sure it will progress. As far as the alternator it seems as if the one I have looks fairly new to begin with being it's clean and new looking. I bought the truck used without much history so who knows. This post helps a lot.

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