So I am having trouble! A few months ago I notice a light noise when driving my 2004 F-150. I took my truck into the ford shop for recall work and ask them to check it out. They told me I needed a new serpentine belt and tensioner and wanted $300 dollars to do the work. They also told we it was something that could wait to be fixed. I waited a month or so and the noise got worse so I talked to a friend of mines dad who is a retired mechanic who said he could fix it. I went to O'Reily's and they told me I needed a belt and a pulley so I purchased and took my truck to my friend. He brought it back to me and said he replaced the belt but the old one was fine and that the pully was fine as well. Well now the noise is worse it sounds like an insect and is completely random it is not made worse by hitting the break or gas, by turning the wheel, or turning on the AC/Defrost. Frustrated, I took it to another mechanic who agreed to look at it at no charge and would try to tell me what was going on. He tried several different things and was able to produce the noise but not as much as I have been hearing lately and determined that my belt and tensioner is fine and couldn't really see anything under the hood that was causing the problem except that I has a fan that had a bit more give then it should but it was not anything major. He told me it was safe to drive but it just continues to get worse and now when I turn it off, and please don't laugh, it sounds like a turkey! Any suggestions as to what is causing these noises?

 

My wife even laughed when I read it to her!

When you got the "pulley", was it "just a pulley" with bearing in it?

Or was it a spring loaded arm (mount) with a clockspring like spring and a pulley attached?

As the truck is idling, looking at the idler / tension pulley .... is it moving in and out as if the belt is getting looser / tighter?

Sometimes the spring loaded arm developes a squeak and it's not the pulley or belt. These belts often have places where they are a little looser and you'll see the pulley move in and out as the tighter / looser spots pass over the pulley.

While it's idling, might also take a small spray bottle with WATER in it and spray the belt just to see if noise changes. I know you have a new pulley and belt, but you also have the noise still.

Lastly, do you have a good 2 foot long hard wood stick (a solid Hickory billy club or night stick is good ... but a simple stick of Pine will do, a cut off broom handle is great) .... with motor running and insects chirping, watch what you do, but hold one smoother part against your ear and take the other end and touch places like the alternator housing, power steering pump, bolt on mount to which the idler / tension pully attaches to ... etc. You'll hear it reall good.

Just dont't touch the belt or a moving pulley!

 

I have heard alternator bearings do the same kinds of noise's you are describing, its possible with the engine shut off too unload belt tension with a socket wrench or breaker bar and spin pulleys on front of engine to find one that is coarse or growls, you may have to have someone hold the bar while you are checking, just dont put fingertips between pulleys and belt. the pulleys can be overly loose or tight to cause problems. are you sure the problem is out side timing cover. that looseness with the fan, was that with the fan hub or water pump? good luck.