c-towndave

My first post.

I have an '04 XLT with a 4.6L 2WD, 60K mi. It runs fine in every way, except when I get to between 65 to 70 mph an annoying whistle/howl develops. When I release the throttle it goes away. When I hit the throttle it's back again.

I'm guessing it has something to do with the air intake, but hoping it's not an intake manifold leak. I have already changed the plugs (one of which was very loose), wires & air filter.

Has anyone else experienced this? Any help is appreciated, as long highway trips with this noise would give me a headache.

Dave

KJoe

Have you tried cleaning the throttle body?

c-towndave

Yes. No difference.

cuban8279

hey check out your filter box and all the connections throughout even the hoses attached to the throttle body. sometimes at that speed the throttle body is almost wide open and suck in alot more air then you would at lower speeds so maybe you got a leak there somewhere. Just tighten all the screws and see what happends. Check all the other vacum lines too make sure none came apart from location.

wde3477

Suggest if it were a manifold leak, you would experience engine operating problems - rough idle, fast idle, etc.

Agree with prior posts - first guess is that you've got a flow restriction, an inlet leak between the air cleaner and throttle body, or a resonance (like blowing over the top of a Coke bottle?) somewhere prior to the intake throttle body.

Does the howl go away over 70mph - that is, does it only occur in the 65-70mph range?

c-towndave

Thanks guys for repsonding. It does appear to go away at higher speeds. It's mostly in that 65-70 mph range .. and it sounds EXACTLY like someone blowing over the top of a Coke bottle. That would be a perfect description.

I will look at the air intake a little more closely and the vacuum hoses. If anyone else has experienced this please let me know.

transmaster

It is the engine. I am new to Ford F150 but I have done all of my own work
on every vehical I have owned for several decades. I am long out of the back yard mechanic status. What you have described could be either a differential that is low on gear oil or has a bad bearing, this last is not very likely just something to check. Also universal joints both the cross "T" and the constant velocity type will howl when they are worn, in the case of UJ's listen for a clicking sound when you let off of the gas at real low speeds. One of the best things you can own is a mechanic's stethoscope. If you don't have one a wooden dowel works great one side to the area you want to listen to and the other to your ear. You can save a bunch of time figuring out a problem doing this. I hope this helps. Once you do find the problem it will be one of those "oh man why did I look at this first" things.

tschneider4x4

I have an 04 supercrew 4.6l as well with the same wind over the coke bottle sound? Anyone have any new ideas or updates regarding the issue? Intake between air box and throttle body or differential fluid level, etc.?

Thank you in advance!

Todd

Good old Bill

Not sure if this is the correct place to offer up my idea as original thread was started 8-4-07. Tschneider4X4, I lean towards Transmaster's post on 11-17-07. Years back, howling noises that could be altered with throttle pressure was actually in the rear end. I would definately not overlook the ring and pinion. Goold luck.

c-towndave

Just an update on my situation (original poster).

1. I had the diff. fluid changed, did not help.
2. I had a mechanic check for bad vac hoses, etc, did not help.
3. I had the throttle body cleaned, changed the plugs, air filter, did not help.

I notice it is very slight around 40 mph, but right at 70 MPH I can hear it over my radio set at a respectable volume. If I take it to 70 MPH, put it neutral, and gun the engine at speed, the sound is NOT there. Therefore it only occurs under load.

My next step is to take it on the freeway with a mechanic to show them what it is doing.

In every other respect, the truck runs & rides perfectly. I will provide an update as I continue into this mystery.