So my 2005 F150 4x4 starting making a rattle when the pedal is applied. From what my passengers can tell, it sounds like it's coming from under/in front of the passenger seat so possibly the wheel well? It happens whenever i'm on the gas, but say I accelerate up to 120 kilometers, take my foot off the pedal the sound will stop, and it will only start again while the pedal is applied. I was wondering if anyone had any insight as to what this could be before I take it into a dealership to get it looked at. Truck has 130k Kilometers on it and no prior problems to my knowledge. No lifts/levels either.

 

Perhaps it could be a U joint rattle. Does the problem change at all when you turn the steering wheel? if so, it also could be a front wheel bearing. Could be a loose exhaust. Not very likely, but you could be missing a front passenger side wheel weight. (i do not mean to offend, im just not aware of your truck knowledge) but is the truck accidentally in 4 wheel drive? A buddy of mine has a 01 f150 and he has a loose exhaust that results in a rattle everytime the gas is pressed, gets worse the harder he accelerates, but once he lets off on the pedal to shift, hit the brake, or when its cruising down the highway under minimal acceleration, the noise and vibration lessens or completely goes away.

I would suggest putting the truck on a level surface, choak both front and rear tires. with the truck off, put it in neutral, with the E brake off, and crawl under the truck, wiggle the front of the drive shaft up and down, and in a circular motion, same with the rear of the drive shaft. If it moves up, down, side to side inside the U joint "housing", than i would recommend replacing them. While your under there, wiggle the exhaust around, check to see if it is easily hitting another part of the truck, check the exhaust connections as well.

I would also suggest getting a friend, put the truck in park or neutral, engage the e brake, start the truck, crawl underneith, have a friend press the accelerater. have him press it rapidly, then slowely, high rpm's, low rpm's. Just to see if the engine or exhaust is rattleing, hitting something.

Again, i am not in any way intentionally insulting your intelegence, im just giving advice and suggestions in the simple'est way possible.

If none of the above diagnose's apply. Shut the truck off, check to see if you are in 2 wheel drive, (not sure if 05's have electronic or manual hubs) but if they are manually locking hubs, check to see if they are in the free position.

To check wheel bearings, Jack up the front of the vehicle until both front tires are off the ground. Go over to a wheel, grab it at "9 and 3 oclock" then try to move the tire itself up, down, side to side, and in any other direction other than the direction it moves when you turn the wheel from the steering wheel. If either one of the tires moves, even slightly, in the wrong direction, or the inside of the tire makes a clicking noise.. it is most likely a wheel bearing.

I hope i could help in any way. And again, i apologize if your a master mechanic and it sounds like im talking to you as if you were a child. That is not my intention. I try to explain things as simple as possible.

 

Not a problem. The 4x4 is electronic and not engaged. I crawled under once at work and checked the exhaust but it was snug towards the middle of the cab all the way to the back, but i'll definitely check further up. Steering does not effect it at all. I already tried putting it in neutral while my brother looked and it did not make the noise accelerating to 4k RPMs in neutral, it seems to only be when the truck is physically moving down the road. I'll have to check the tires next time i'm at work and have access to the lift (18 year old working in a shop for the summer). I'll definitely go outside and check those other things you suggested though.

 

a lift is definately a nice luxury to have haha.

My ol' 89 f150 has bad rear U joints, and i notice a vibration when the vehicle is under load, but once i get the truck over 60mph the vibration completely stops. I dont think you mentioned doing this, so ill also suggest...

While your driving on a safe flat long stretch of road, make your truck do the vibration thing. While it is vibrating and doing what it does, just take your foot off the pedal, and quickly put the truck in neutral. If it still rattles or vibrates while the truck is coasting at the same speed, than i could almost 100% tell you it is a U joint issue.

As dumb as it sounds, check your tire pressures, and the physical tire rubber, maybe theres a bubble or something on the tread.

Also, have you been wheelin with the truck at all lately? or went through and mud recently? if so, you could just have mud on the inside of the tire, or in the brakes or something. A couple years ago, i got my one of my old trucks stuck bad out in the woods, and it was having similar symptoms for a few days to a week, and come to find out it was just mud caked all over the wheels and what not.
Im only 21, so i figured id ask, cuz when i was 18 i was doing reckless things with my trucks, and alot of the time, the hardest things to figure out with my trucks, were actually staring me in the face the whole time lol

 

I don't really bag my truck, but I did take it off roading about a month ago and got stuck in some mud, but I quickly washed it and the noise didn't start until a few days ago. It almost sounds like tin on tin rattling. When I shift my truck into neutral the noise stops, it's only present when throttle is applied. I'll double check my tires and wheels though also.

 

i hear ya, this is a tricky situation... it could be the bearings inside the tranny, where the drive shaft goes into the rear of the trans. my 2003 ranger had almost the exact issue a whileeeee ago now that i think about it, but the tink sound was pretty loud. but im pretty sure the tink tink didnt stop when i put it in neutral, and i replaced the u joints, wheel bearings, rotors, pads, greased everything, checked the motor mounts, and so on and so forth. and i did the u joints last, and the noise and vibration stopped.

its possible the previous owner changed the joints, but forgot to grease them, so the individual little bearings are making noise and its loosening up creating the vib. but not loose enough to feel alot of play in the drive shaft.

or there just original joints and going bad.

just thinking out loud. i know how frustrating it is to have a nice truck that is acting up.

But like i said it could possibly be a loose or cracked motor/tranny mount. or a bearing or something inside the trans.

 

I had a rattle that I thought was the heat shield from one of my cats. Turned out to be the passenger side brake shield. I removed it then backed it with a few pieces of padded tape before reattaching it. To diagnose it, tap it with your fist or rubber mallet. You'll know it when you hear it.

 

You sure it isn't spark knock? Try a tank of high octane fuel to test this theory.

 

So I found out what it was. My passenger front wheel bearing needed to be replaced. I work at a shop so with our Ford discount it was $215, opposed to the almost $400.