I have an odd noise that I cannot identify and was wondering if anyone had any ideas.

I have an 04 FX4 and when driving I will occasionally hear a sound that is similar to blowing over the top of a bottle, or a very muffled horn.

It is not constant, it does not change pitch or frequency with engine speed, it is just sometimes there. Almost like there is a owl under my hood.

It seems like it is coming from the front drivers side area, but it is hard to tell from the cab.

I had the wheel bearing changed on that side in Feb of this year, I did brakes and rotors about a month ago, but I was hearing the sound before the brakes.

The only thing I did notice, is that when I was doing the brakes, when I spun that front wheel by hand, it looked like something on the CV boot was rubbing as it spun, I thought it might have just been due to the angle since it was jacked up on that side.

Since the sound is intermittent and doesn't vary with speed, I was not looking at the CV as the issue.

Any ideas are appreciated.

 

It might be this:

Make : FORD Model : F150 Year : 2004
Manufacturer : FORD MOTOR COMPANY
Service Bulletin Num : 17781 Date of Bulletin: MAY 01, 2004
NHTSA Item Number: 10008555
Component: ENGINE AND ENGINE COOLING:COOLING SYSTEM
Summary:
HOOT, MOAN, OR WHISTLE FROM COOLING SYSTEM AT 2200 RPM. *TT

 

Make sure air filter is clean. roof racks tubing?? tube type Running boards???

 

Manual, I cannot find the text of that TSB anywhere. Do you have a copy of what the details are?

Well I replaced my AF last night while doing the oil change. No roof racks, but I do have tubular running boards. I will check to make sure the front caps are still there.

 

There is a restriction in the coolant line to the heater core (has like a black metal zip tie on the outside of the hose), apparently those can make noise and I believe that's the TSB he was talking about.

 

17781 2004 f-150 - hoot, moan, or whistle from cooling system at 2200 rpm
some 2004 f-150 vehicles built at kansas city (11th digit of vin 'k') from 3/4/04 to 4/19/04 and at norfolk (11th digit of vin 'n') from 3/28/04 to 4/14/04 may exhibit a hoot, moan, or whistle at approximately 2200 rpm that appears to be coming from the cooling system, heater hoses, or heater core. To service, install motorcraft cooling system stop leak pellets (vc-6) per the directions given on the product's label and then operate the engine for a minimum of five minutes.
Effective date: 05/10/2004