On my 08 5.4 with 91,000 miles there is a high pitched whine coming from my engine at higher RPMs. I have replaced the belt with a gator back belt and the power steering fluid level is perfect. What else could it be?

 

It could be several things . How is your tensioner , idelers . Is there rust on your pulleys ? Is there build up in the grooves of your pulleys ? Many things , even not belt related , could be your noise .

 

The tensioner was replaced last time I took it to the dealer for warranty work. I will look at the pulleys and see if there is any rust tomorrow in the daylight. If there is just knock off the rust with a wire brush?

 

Pulleys should be clean . No oil , rust ,coolant ,belt residue or other bad stuff . Remove the belt and check all the pulleys for bad bearings . Start the truck with the belt off to see if the noise is gone without the belt . If no noise with the belt off , something the belt drives , the belt ,or the tensioner is bad . Rust can be cleaned off with a wire brush .