Loud humming noise coming from bed?

[JJMaine]

As some of you know I’ve had a whining type noise and I cannot figure out where it was coming from. Well today when I starting my truck it had a loud humming noise almost a droning noise. I drove it home and left it running and when I got out I noticed it is super loud standing by the bed of the truck like the bed is amplifying it. This is with the truck in park, running.

If I rev the engine, the whine/hum seems to increase with the rpms. Could it be the fuel pump? I have a video on my phone of the noise (for audio only as my camera doesnt focus). If anyone wants a listen and can show me how to upload it here? Thanks!

The noise is so loud now that the bed is vibrating.

 

[JJMaine]

I said humming noise but its more like a howl

 

[JJMaine]

I just put a stethoscope inside the bed and it's very loud but put it on the fuel tank next to the pump and it's dead silent so I don't think it's that. Could it be the tranny? That might also explain the slight knocking with with with with should I get when I put the truck in drive or reverse? I need to get to the bottom of it because it got significantly worse today so I don't think it'll be long before whatever it is gives up the ghost.

I drove down to the store (flat ground) to check the tranny fluid and it appears to be overfull, about 1/2 above the high mark. Could this cause such issues? I'm stumped.

I popped the hood and the engine sounds perfect and you don't hear the noise until you come around the side of the truck

 

[pentode]

I'm going to go out on a 4 beer limb here... I think you've got a harmonic vibration. The bed is acting like a speaker and amplifying a vibration that's coming from somewhere else. In park, there's nothing in the back of the truck that's moving... in fact the only things that have moving parts are, as you said, the engine and transmission (other than the fuel pump, which it seems you've ruled out). Possibly put the stethoscope on the tranny and see what you hear? Just don't blow your eardrums out as I always seem to manage to do.

 

[JJMaine]

I did put the stethoscope on the tranny and heard some noise that sound metallic but I guess if you put the stethoscope to any transmission you would get some noise. Just odd that it got really loud today. I sat in my truck today at lunch for 1/2 hour and it was quiet. Now the loud droning howling sound coming from the bed drowns out the engine noise. What could have changed from the time I ate my lunch until the time I started the truck to leave the job site? I swear this truck will give me a stroke haha.

I guess as Blumpkin says, "Just gonna send it" and see if something breaks. I guess if the tranny goes, I'll get a fresh one and won't have to worry about it for a while.

I got a serpentine belt tool so I can take my belt off this weekend and check all of the pulleys and harmonic balancer because I get a chirp sound everytime I take off around 1500rpm. Many strange noises, I should have bought an S10

 

[pentode]

Can you feel this vibration? Or just hear it?
I'll be honest, I've never had a 5R55 apart (assuming that's what you have) so I don't know what's turning beyond the pump. Again, tipsy brainstorming but the only thing that springs to mind is input shaft bearing.
You heard metallic like clanking impact-type noises at idle or what?

Edit: Send It always either proves there's no problem or reveals exactly what the problem was.

 

[RobbieD]

Get under the truck and check the heat shields that are spot welded to the exhaust system, and riveted to the bed.

I've had loose heat shields make a buzzing or droning noise before. Whacking stuff with a rubber mallet is useful for finding a loose part.

That may be the problem; or, you'll rule it out as a cause.

 

[pentode]

Get under the truck and check the heat shields that are spot welded to the exhaust system, and riveted to the bed.

I've had loose heat shields make a buzzing or droning noise before. Whacking stuff with a rubber mallet is useful for finding a loose part.

That may be the problem; or, you'll rule it out as a cause.

Oh yeah, this is better than my theory.

Edit: WAY better. "When will I ever become a good mechanic?" said in Napoleon Dynamite voice.
Edit2 : I'm doubling down on the harmonic theory though - are there any heat shields attached to the bed or frame in the back?

 

[RobbieD]

In my mind a humming loose part could be described as a harmonic-induced noise.

"When will I ever become a good mechanic?"

If I ever become one, I'll let you know how I did it.

In the meantime, I'm perfectly content in boldly going where no shade-tree mechanic has gone before.

The way I screw up stuff, I'm my own best customer.

 

[JJMaine]

I can feel it shake a bit at idle and seems a little more prevalent now but it could just be me imagining that its worse. That is one of the reasons I have been going down the list of things to fix a rough idle.

Earlier when I was investigating, I revved the truck in park and when the idle came back down there was a slight thump. I tried to replicate it but couldnt. I have no clue if that ties into this or my chirp at 1500rpm when first accelerating. Or maybe its all one issue.

It could very well be something loose and vibrating now that I think of it. When I first bought the truck. The previous owner had 2” lift keys in it AND had them cranked to the max. The rear has 2” lift shackles and the front was almost 2” higher than the rear! Needless to say, it was a ROUGH ride and the first time I drove it to work, the front skid plate was dangling by one bolt (thank god that didnt fly off and destroy the underside of my truck). But who knows what else may have been battered loose by the previous owners sweet lift job.

When I took the front shock off to replace them, the shaft flew right out of the shock body.

 

[JJMaine]

I’ll update you guys tomorrow while I’m on the side of the freeway for 5 hours, waiting for a tow truck.

 

[pentode]

In my mind a humming loose part could be described as a harmonic-induced noise.

Indeed. If the bed sounds like it's humming, I'm still betting on harmonic vibration, but you came up with a way better likely source than me. I'm going to say my brain was very distracted my the title "loud humming noise coming from bed"... I went a whole different place and I fully admit I have a few problems.

 

[pentode]

As some of you know I’ve had a whining type noise and I cannot figure out where it was coming from. Well today when I starting my truck it had a loud humming noise almost a droning noise. I drove it home and left it running and when I got out I noticed it is super loud standing by the bed of the truck like the bed is amplifying it. This is with the truck in park, running.

If I rev the engine, the whine/hum seems to increase with the rpms. Could it be the fuel pump? I have a video on my phone of the noise (for audio only as my camera doesnt focus). If anyone wants a listen and can show me how to upload it here? Thanks!

The noise is so loud now that the bed is vibrating.

You can upload a private video to youtube and post a link FYI... This is what I do... if they want to struggle their way to make saleable data from engine noises, let them try I say.

 

[Lefty]

Maybe your Ranger is haunted.

 

[JJMaine]

yes, haunted by the previous owners missing brain cells.