I have a 2002 3.0L 2wd. I just noticed it about a week ago and it does it everyday however only in drive. I cannot determine where the sound is coming from but the sound doesn't change much with the RPM's

While decelerating, the same sound appears but goes away at 2 or 3 mph.

It is bugging the crap out of me, please help

 

check your wheel bearings for proper grease

 

I don't think it is, since if i put it into neutral while moving the sound goes away, even if i rev up

 

manual or automatic transmission

 

Find a spot where you can drive close to a retaining wall or building in a quiet area.

Use this wall or building to determine if the noise is from the front or back , left or right.

Just do the same thing that makes the noise appear with the windows down the wall should reflect the noise back to you.

Or just get a friend and tie strap him or her under the truck

Wheel bearings normally will make more noise while turning from side to side, so it is not likely your problem.

Ujoints could be the issue but it is hard to tell by your description.

It is easy to inspect the ujoints if you think they may be the problem.

For now check all the basics regardless if it may be the cause of the problem or not. I would inspect the bearings for play just in case, check the brake pads and shoes and remove the drive shaft to check for play and or binding bearings in the ujoints

 

i had that whistling sound , it was the driver side front wheel bearing

because it is the side that supports the most weight at all times IE: driver and fuel tank

 

Update: So it happens in reverse too. and like i said it's not all the time. I can pull out of my neighborhood without hearing it but on the next launch I will.

I cannot hear anything over 15 miles per hour but that may be due to the aggressive tires

 

it could also be the pressure relief valve inside the fuel filter

i had that problem on my 2010 mazda b4000

how long since you replaced the fuel filter

 

Update: I used some lubricant (the advanced auto generic kind....WD40 knock off) on BOTH driveshaft U-joints and the sound goes away for a day or so....

so I guess I need to replace those, any tips or tricks? I've never done them before

 

if you have never replaced u-joints before

my advice to let a mechanic replace them . because if you replace them and something catastrophic happens
you will be legally liable

it is one of those repairs that is best left to a licensed mechanic for legal reasons