2007 Ford F350 88,000 miles 6.0 power stroke diesel whining only during acceleration, once rpm is high, sound disapears. Sound driving me nuts coming from the engine area. In Park it doesn't make the sound to actually hear/know where it is coming from under the hood, it only makes the sound during acceleration. Had this truck for 4 years only done regular maintenance, nothing else needed. It's heaviest work load is plowing in the Winter in the North, otherwise parked in a heated garage. Spring/Summer/Fall driven 2-3 times a week in town. Once a month driven 50 miles hwy. Any suggestions what this whining noise could be?

 

How's the power? Boost leak maybe. You could try and power brake it in the driveway and see if it will make the noise.

 

Y pipe leak?

 

Y-pipe is very possible.

 

Bellow on y-pipe or boost leak. My y-pipe bellow just blew and started a very high pitched whistle. Went underneath the truck with a flashlight and bingo, saw that there was a leak in the passenger side bellow. I'm probably going with the MBRP y-pipe as it is $238 at Performance Truck Products with code MBRP15 and free shipping.

 

 

Very nice, glad you found it and thank you for the update with photos. Reps given.