Hey all,

I have a 2005 Expy EB 5.4 4x4.

About to turn it over to my wife as I take delivery on my F350 DRW.

Here is the issue I am chasing. When it is cold out, there is a whistle that occurs at various RPMs. if I change the RPM, it goes away. Frequently happens when on the highway at around 68mph. accel, or decel. Or climbing up a hill.


I know it's vaccum someplace, but can't figure it out. no codes, no other issues, just a whistle.



If anyone has any suggestions, they are greatly appreciated.



Glenn

 

Well obviously it could be any one of the numerous vacuum hoses under the hood. For those you would just have to take the time to carefully inspect them all. Other than that, I would suspect the air intake duct, or perhaps the IAC valve is sticking and not fully closing.

 

just an idea but are you sure it's a whistle and not a whine coming from the rear end. does it seem to only happen when are just tipping into the the throttle?

 

I have a 05 Expedition XLT with this same issue. It only whistles when really cold, typically under 20 degrees outside air, but goes away once the truck warms up. It's been doing this the past 3 winters and nothing seems to be affected.

 

I posted this for SOWAXMAN on another thread,I hope it helps;
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No...only when under load in drive. Seems to be related to rpms in the 2500 range
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This will seem strange but, the only thing that keeps coming to mind is a possible small vacuum leak at a heater control or in one of the vacuum hoses. I suggest that you get a vacuum gage and see what the reading is at the time that you hear it start and again when you pass out of the sound, then in an open space, set the parking brake and block the wheels and try to duplicate the vacuum readings at a standstill by having the truck running and in gear, if you can duplicate the sound you will need to get someone to feel around under the dash until they touch the offending hose or componant causing the noise to change or go away. I had a similar problem under the hood of my Mark VIII a few years ago and it was a tough one to find. In my case it was a molded hose that was collapsing at a certain vacuum reading and eventually cracked enough to make the irritating noise.
Good luck with it and let us know what the fix is.

 

I have a 2004 5.4 expy, and I think I have the same kinda of noise. Tap the throttle a little, noise goes away. However, I think its more of a bearing noise. Only does it when below 0 out. Brother has a 2003 F150, same noise. Thinking possibly alternator. The "whistle" noise is usally around 1200-2000 rpm range.

 

Thanks, I'll check that out. First thing I have to do though is replace the blower motor resistor..

 

Are u guys sure its not the belt balance shaft.
I swear there was a thred a while ago about this issue on cold start up.
my 05 also whistles when its cold on start up

 

My 2004 F150fx4 has the exact same problem. I had the full K N filter intake system on there and took it off and put the factory air intake back on.
Same noise. Had the drive shaft completely relpaced. same noise. Had thr rear differential thoroughly inspected. Same problem. Only when the outside air temp is below 18 F. I certain it's a vacuum leak. Don't know where though.
If you find it please email me hawker123@***.net
Thanks Patrick

 

Same thing here 03 Expy, after it warms up its all good but when cold out it whistles just as describes. My thoughts is either A) Vacuum Line or B) Some sort of metal that shrinks and causes a gap but when heats and expands fills the gap... just my thought... subscribing hoping to figure this one out