Originally Posted by MrFL54
Kinda new to the forum but been here lurking for a while. I have a 2005 F250 6.0 and sometimes while towing I hear what sounds like the engine reving up. It is not the engine as I don't see the tach reving. It has done this a few times lately and once without towing anything. Truck is bone stock and has 72k miles. I am in the process of figuring out what up grades to do. There were a couple of posts of people that had the same issue but doing a search I couldn't find them. Thought it could have been a fan clutch. Engine temps and trans are normal, well as normal as the idiot gauges would read. Any help would be greatly appreciated. Thanks
Like mentioned in post #2, that noise is your fan coming on. It is controlled my the PCM and it isn't like the fan you would see on a gas engine. When it comes on, it roars and could be mistaken as sounding like your engine is revving. Nothing to be concerned about, its normal.
As far as looking at "things to do" you should click on the link in my signature "basic info" that will bring you to a thread on a different forum. Post #2 is full of information about what every 6.0 liter owner should be aware of.