Whistling noise coming from the front

[Gruz7]

So for quite some time now there has been a very faint whistling noise coming from underneath the front of the truck but only when it's in gear and it is most noticeable when I let off the gas and coast at around 15-30 mph.

I am really thinking that it is not the vacuum and that it is something entirely different although I'm not exactly the "repair-guru".

When the whistling is noticed it could be around 25 mph then as the truck slows down it will become less significant or quieter in slower repetitions.

The truck is a 2003 Ford Expedition XLT 5.4L with a magnaflow cat back and 163k on it. Never had any major issues and it will be serviced in the next few weeks as routine.

Thank you to anyone who can help!!
Jared


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[Gruz7]

Just to add another point I do drive my truck in A4WD at all times.

I don't know if this could be the cause of the whine/whistle noise because it will still occur when the truck is in 2WD.


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[metaldrgn]

It's almost impossible to tell without actually hearing it for myself. It may be the rear differential if you change from 4wd to 2wd with no change in sound. I would check the fluid level, you may be a little low. The seal may also be leaking and if it gets low it won't have enough lubrication and will start whining. I don't know what the schedule is for that but it may be time for a diff fluid change. The sound probably won't go away if that's what's causing it, but it shouldn't get worse. That's if you get it serviced. If you don't do anything and it gets louder, it's more than likely a differential, probably the rear one since the noise is usually load dependant. It could also be a panel underneath hanging just in the right way that is causing the passing air to sound like that.

 

[Gruz7]

It's almost impossible to tell without actually hearing it for myself. It may be the rear differential if you change from 4wd to 2wd with no change in sound. I would check the fluid level, you may be a little low. The seal may also be leaking and if it gets low it won't have enough lubrication and will start whining. I don't know what the schedule is for that but it may be time for a diff fluid change. The sound probably won't go away if that's what's causing it, but it shouldn't get worse. That's if you get it serviced. If you don't do anything and it gets louder, it's more than likely a differential, probably the rear one since the noise is usually load dependant. It could also be a panel underneath hanging just in the right way that is causing the passing air to sound like that.

I'm taking it this week for regular service and maintenance, ie. Oil change/fluid change. Should I tell the dealer to change the diff fluid as well? Thanks for the help


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[GAINMOB]

I think its nothing becuz so many ppl complain of it that its almost normal...mine could be doing it but i'd never know cuz I have my bass on

 

[metaldrgn]

I'm taking it this week for regular service and maintenance, ie. Oil change/fluid change. Should I tell the dealer to change the diff fluid as well? Thanks for the help


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Actually you can try one more thing. While driving at the speeds it's most noticeable, put it in neutral and see if the sound gets quieter.

 

[Gruz7]

I think its nothing becuz so many ppl complain of it that its almost normal...mine could be doing it but i'd never know cuz I have my bass on

So I've tried tons of different things while driving and while idling but the thing that stands out most to me is the 4WD. I think that my 4WD is staying somewhat activated even when I put the truck in 2HI


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