So my truck started making this noise and I'll describe it best I can to see if anyone has any suggestions on what it could be. When I hit the gas it sounds like it's making a loud noise that sounds like the engine reving. The rpms are fine and it seems to be shifting fine but I can't figure it out. I have 35's on there, but I've had them on there for 7 months now and know what tire noise sounds like. Its not the tires. In the cab its very loud, but as soon as I ease off the gas it usually goes away. It just started one day last week. One day fine, next day this noise. It's in the shop now for an emmisions pressure blah blah blah, and I asked them to check it out, but I'm going to think that they just write it off as tire noise. THe other thing that has me concerened is since I've heard this noise I am now getting 8.55 miles to the gallon. I was fine with the 11.62mpg, but this is ridiculous. ANY IDEAS???

 

Mine makes a similar noise sometimes. For no reason and and doesn't do it much. I've isolated it to the fan. For some reason the fan clutch engages and makes a heck of a noise but will usually go away after a few minutes of driving. This is after start up on a cold engine. I would expect to hear it if it was at high temps in stop and go driving to cool down the engine. Never have figured out why it locks up like that on a cold engine

 

If you have a mechanical fan this is called "fan sickness". The viscous fluid in the fan drains down and pools near the bottom. After the fan engages and circulates the fluid it goes away. Not a problem so much as an annoyance because it sounds like a problem. No functional effect on the engine.

 

That definately sounds like it makes sense. I did start making this noise about a week after a mudding trip. It's at the shop now for something else (I got water in my "vent of the gas tank"). No more submerging the truck in water. Could that possibly make that noise, or is it more likely that it's the fan? Thanks

Mike