My 2005 87K FX4 5.4 has a noise in the engine that is only there when the truck is at normal operating temp. It sounds like an idler pully might sound if it was starting to fail. Sort of a wering with a slight whistle mixed. I've had it to the dealer with no help from them. They say they have no idea what it could be. I know it's almost impossible to diagnos via email without actually hearing it in person but has any one had a problem like this? It started seemingly after an oil change. Ford filter and 5-20 oil. The dealer said it could be an oil pump. I never heard of such a thing!
Thanks in advance for any help!!

 

I should also add that I just bought the truck a week ago. It's my first Ford...always have had Chevys. The last one was a 153K Silverado that is still going strong. I hope the Ford will do the same.
Anyway, I noticed that the noise seems to come low and in the center of the engine trans area. I also noticed that the truck does not hold it's self on an incline. The same road that I drive everyday has a hill with a stop sign. The Chevy held it's self in place with minimal brake effort. The Ford rolls back like the clutch was pushed in , if it had one, if I don't hold it there. I'm wondering if the noise could be trans related??? Your thoughts???

 

I replaced 1 of the tensioner pullies at around 60,000. It was a distinct "ringing" noise. I ended up taking them both off and spinning them on my finger, I knew right then 1 was bad.