I guess i'm joining the rest of you that have this problem. My 04 Screw started doing it about a month ago. We've been unseanonable warm here in New England for the first few months of winter but as soon as the temp started dropping to about 5-10 degress the noise started. Kind of like a hollow howling noise whenever the engine is at constant RPM's or even light acceleration. My guess at first was something to do with the intake, power steering pump, pullys, or even the alternator, but now i'm starting to think that it might have somehing to do with some kind of air leak in the throttle body. Someone tell me if this makes sense to anybody:

In cold weather rubber seals become compressed and don't expand as they would in warm weather. So what if the seals that go between the intake to the throttle body become so cold and compressed that under light acelleration or idling some air is being sucked in through small leak in the gasket because of the vacum effect of the intake. By the air being sucked in through such a small opening it creats this noise almost exactly like a whistle works but reversed. Instead of pushing air through a small opening its sucking it in making a howling noise.

I can't think of anything else. Some people say that replacing the alternator fixed their noise but I don't feel like paying for a new alternator right now so i'll just have to mess around with the intake system and see what happens or just deal with the noise untill the weather warms up, haha. If anyone else thinks that the vacum leak might be the problem post your replies and let us all know what you find.

 

Had my alternator changed yesterday and no more squealing at those rpms where I noticed it before.

The mechanic said he had changed 7 in the past few months, mostly 2004-2005's but said he had not done any 2007's as of yet.

I still love my Ford F-150

 

I wish I had an answer to this, I know it's related to cold temps. It happened today driveing around about 30 mph. Like I said before, it sounds like a harmoic whine sound. I got it for a few seconds then I very quickly hit the throttle and backed off and it went away. RPM's never changed. Tried to duplicate the same again but the noise didn't come back. It seems to me that it's a combination of temp and throttle position during cold temps. Since my RPM's never changed but the throttle position did for just a split second. I have to think it's related to cold temps and throttle position. If it was an alternator going bad, I would guess the noise would continue. Of course my RPM's could have increased a little, I didn't notice it on the guage. I'm starting to think it's in throttle body or maybe the O ring under it. Guess I'll have to so more tinkering.

 

The reason I joined the forum was because of this high pitched noise issue. Reading these and other threads around this forum has really been humorous. People have accurately described the noise, symptoms and how (by replacing their alternator) it was fixed. Yet many are still chasing intakes, windshields and even sensors.

Then it hit me. The exact words from the service writer when she called to tell me they found the problem were "your not going to believe this". I realize now that if the dealer had not found it, I too would be one of the people still chasing other fixes. It's hard to dump the money for an alternator if your not positive.

I had to ride with the first tech and point out what noise I was talking about. When he heard it he thought maybe transmission? Two days later one of the dealers top driveline techs drove it and new right away it was the alternator. The best description I have heard is the sound that long stem crystal make when you rub the rim with a damp finger. Also, I have only heard it a specific rpms.

 

HwyTraveler
Since you had your alternator replace has your truck made any more noise at cold conditions like every body has talk about ?

 

Glad to hear you got the problem solved by repalceing an alternator. I have replaced a bunch of alternators in my day and I must say this is a new one to me. I must be hearing a different noise than most others. If I can't locate the "problem" meaning I really don't think there is a problem, I'll replace my alternator,,,Grrrrr this is so stupid, So I can see if this cures the problem which may come in June when the noise goes away again, which I will wait till next winter to hear it again on rare occasions.

 

When the temp gets down around zero or below I might get some noise on start up. It will last a few seconds and then taper off. But that is a completely different than the high pitched ringing I was getting from my alternator. That sound is completely gone.

 

I just got a call from my dealer who spoke with some other dealers and Ford to confirm what they're hearing. (They've had 5 other F150s come in lately with the same noise). It's something to do with the alternator but nobody really knows what it is inside the alternator that is making the noise under cold temperatures and when the engine is under load at those temperatures. However, an alternator replacement is fixing the problem. The truck goes in tomorrow to have this done.

Duke

 

Not to beat a dead horse here guys...but I had my alternator replaced and at the same time had the technician install a Gatorback surpentine belt late yesterday afternoon and took it up to speed on the freeway this morning. No high pitched whistle like before!! Completely quite. It was -3 degrees in Appleton, WI when I did my test. I hope this information helps!

 

Thanks HwyTraveler for your input.

 

Hey waymur, which dealer did you go to?

My local dealer hasn't the slightest clue where to look and I have no patience to be their first guiny pig on a fix.

 

I had the same problem with mine drove me nutty. the only thing i could place the noise coming from was like maybe the driverside area bi the wlower windshield. anyway i located it to be the rain gutter(the black molding inset outside the truck) ive noticed it was loose and the passenger side was not. had a new one installed and the noise went away.

 

did anyone find the cause of this. i heard it could be PCV valve

 

I haven't, but the high pitched squeal has been happening a lot this week on my f150. It was zero here this morning and I heard it all the way to work. I've noticed my squeal will disappear if I apply more gas or let off the gas. It only happens when I'm at a steady speed normally around 50mph.

 

Spoken like a true Montana mechanic! I've put up with that horrible, embarrassing squeal since my outfit was new. All I ever got from dealerships (plural!) was "you'll have to leave it until it gets cold, then we'll *try* to find out what it is". I had them replace, at my expense, the belt, the belt tensioner, both idlers and the fan clutch. I finally came back to this forum and found it was the alternator. I purchased a new one, installed myself, and the seven year noise was gone! Just GONE! You're right in one respect, Grrrr this IS so stupid! I'm now going to sit down with the General Manager of the dealership and have him try to explain why I should trust his shop to service my vehicles, including the one I just bought from that dealership.

This forum has been a really great source for finding problems. I thank all who contribute!