Hey FTE Folks! I'm a new member and first time Ford owner. I purchased a used 2010 F250 FX4 6.2l PSD with 90k miles on it. I've been using it primarily for towing a camper. On our most recent trip back home, it developed a 'noise' that I'm hoping maybe someone can help me pinpoint the source of. (I haven't taken it to mechanic yet..)

Some initial details:
- The noise only occurs between 2300-2500 RPM.
- It does not occur every time it hits this RPM range maybe half the time.
- There is no change in RPM/Speed when the noise occurs.
- No engine warning lights.
- It happens whether I'm in regular mode or tow/haul mode.
- I haven't tried to reproduce it yet w/o towing.
- To get in the specific RPM range, the truck downshifts while towing up a hill, so 4th gear?
- 5-speed transmission
- Bone stock, no tunes or anything.
- I did just start using Cetane booster from Ford but I don't see how that would cause any noise.. I'm just putting it out there cause that is the only thing that has changed.

Noise details (bear with me... hard to describe noises sometimes)
- When I first heard it, I thought the noise was actually the trailer going over the rumble strips along the edge of the highway... but I wasn't.. so that is sort of the pitch of the noise when it starts...
- Once it started occurring regularly and I started to pay attention to it... the noise starts off as sort of a low pitched noise (See above) but then quickly goes up in pitch over the course of 3-5 seconds and then goes away! It won't come back until I go out of that RPM range and then come back into it... and then only sometimes.
- Another way of describing the noise is that sounds like something starts slipping (low pitched) and then starts slipping more and more (ramp up in pitch) and then stops slipping (noise goes away).

Any ideas? I'm not sure if it is transmission, engine or turbo?

Thanks for any ideas!

matthew

 

could it be turbo squeal? Towing heavy and getting up to speed sometimes the turbo makes funny noises when it spins. Ever hear the sound a big rig makes in the summer months and with the a/c running, high pitched squealing

 

It could be turbo.. but it isn't a high-pitched noise.. is starts out very low and ramps up to a medium pitch and then goes away. It is also very specific to the RPM range... thanks for the reply...

 

doesn't have to be high pitched to be turbo noise

 

do you mean 6.4? could it be the idle pulley? I've heard those can crap out pretty early on the 6.4s

 

Yes.. 6.4l. The sound doesn't seem like a belt squeel to me.. but I'll look into that...