Hey everybody,
Now I have a whistling noise coming from somewhere under the hood. It happens around 35-50 mph. It doesn't really sound RPM dependent but its really hard to tell. I found this video on you tube and its exactly that noise (its not nearly as loud, but the whine is the same).

http://www.youtube.com/watch?feature...&v=rdpDiQDQUvg

The kicker is that I replaced the alternator (with a used one from a 2008 4.2 with 8000 miles/ buddies truck). Unless its just crappy Ford alternator problem I am stumped. I replaced the idler pulleys and took the ac pulley apart and inspected the bearings and nothing.

To me it sounds like alternator bearing still, but 8000mile alternator shouldn't be doing that. I inspected the air intake and everything is tightened and I can't see anything thats a problem.

I read a bunch of posts about whistling, never a video. Whistling can mean many different things to many different people. Give the video a listen and lets see what you can come up with.


I did replace the grille with the exact stock replacement (bird flew in)...

If you had this before and got rid of it please reply its really annoying and embarrassing with other people in the truck.

 

Wow, not a single reply. Considering how many whistling problems people had with their truck... Nobody got any idea?

Well, I replaced the alternator again with one that had about 40K on it. I refuse to buy a new one for 2-300 bucks. Thats just insane. The noise changed and its very minimal (only between 40-50mph now). So, there is either something wrong with the Ford alternators (which people mentioned before, close bearing clearance etc..). There may be some kind of problem with the charging system as well. Maybe the wiring is inadequate, or possibly, the battery may just be charging enough thus putting a bit more strain on the alternator. Those are my conclusions.

I drove with the grill off, took the antenna off, taped around the bumper, taped around the windshield and around doors (masking tape) NO CHANGE. It must be the charging system and most likely POS alternator design. If that is true. WAY TO GO FORD

 

How old is your battery? *ALL* alternators tend to whistle when they are constantly charging. My battery is about a year and a half old and the alternator is about a year old, and it whistles for a minute or so after starting it when it's been sitting for a while. The power steering pump can also whine.

 

mine has done it the past 2 winters. 47,000 miles 2008 XL model (4.2) only when it's cold, gotta be alternator.

 

My 2001 4.2L did exactly that same noise but only when the temp got down around zero. Never did figure it out.

 

Shot in the dark... but.... Did you check your power steering fluid?

 

If you ever figure this out please post the solution. My 2002 4.2L started doing this too and only when its cold out and just while cruising around at about 2000 rpm it wont do it otherwise. Some days i really love this truck other days i could park the thing in a field and burn it.

 

Nothing has changed at all since I started this thread. The noise is there between 40-50mph. It goes away with higher speeds. So, I started listening to the radio lol. I towed stuff, I sat in the car for about 30 minutes with only the battery on and everything was ok. I guess I'll wait to replace the battery until its going out.

I did take apart some pulleys and inspect the rest of the serp belt system and nothing makes that noise. So, I am just waiting until something goes and then replace it.

Many people have had and still have this problem after thousands of miles, so I am not worried. If it gets worse I would replace the battery. That seems to be the biggest problem solver from all the posts I read. A new alternator (other than Fords stock one) seems to help too.