Low frequency, oscillating humming... what is this?

i6chick

i6chick

It's all about leverage
Joined
Mar 22, 2009
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409
So the past year my truck has been making this super weird, very low frequency humming sound. The hums happen every second or so, happens when it's warm outside. Can't hear it or it doesn't happen when I'm driving, only happens at idle. In gear, or out of gear. RPMS don't move at all. Runs completely normal. The best way I could descride it is a very very deep noise (almost like bass) that sounds as if its coming from a vibration...

Ideas?
 
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Foot on brake or off brake? Sometimes the power steering/hydroboost can do what you describe. Any whine when you turn the steering wheel?
 
P/s fluid is ok, yeah theres a little groan, always been. Not bad. Steerings not hard.

Foot on or off doesn't matter. In or out of gear, makes no difference. If I lightly idle forward or coast at a very slow speed the sound gets a little faster but still just as deep.
 
Check to make sure nothing is rubbing, transmitting engine vibrations to the frame or cab.

Also, something in my accelerator pedal is wore, because it transmits a lot of noise with my foot on the throttle. Set the cruise and it goes away... :doh:
 
Thanks guys for all the suggestions, keep em comming. If I ever get a lunch break I'm going to start checking your suggestions.

This is new, just started yesterday... this humm now comes with a little "shudder" happens only when weather is hott (every day in fl) rpms do not change.
 
Mine used to do that, then it just went away. Thought for a while maybe it was a TC bolt backing out or something, then checked PS pump, and damper, never did figure it out.

At what rpm exactly does it go away? Do you think it's actually going away with higher rpm's, or you just can't feel/hear it anymore do to engine noise/rattle?
 
Lol, A/C is busted. I don't have the motivation to pull the dash out and do the evap so compressor is out.

And I can really only hear it when I'm coasting or idling. Ill drive it here after 530 and tell yall if it does it under light acceleration but I think I can only hear it coasting under like 12mph. Any throtte and it goes away or is drowned out by all the other noise she makes.
 
Nah, not that kinda noise. It wouldnt hum consistently either. I havent been on Comp D in so long I forgot how helpful it was! :)
 
How about the fan, tar'd and feather'd from the puke bottle. Just enough to throw out the balance and cause harmonics.
Just a thought!
 
Alright, checked most all of the suggestions ya'll have graciously provided me. All ok.

The sound has changed.

I may or may not have taken my truck to mudfest and abused her slightly. Just after her woopin I noticed the noise is now a constant deep hum of the same low frequency. It's no longer oscillating and I can almost feel it (unless it's in my head).

This is driving me bat sh!t crazy. Any more words of wisdom?
 
is your airdog all tight? i used to have e raptor pump and a pinhole on the metal line of sending unit so it could suck air. sounded just how your describing it
 
interested in what you find out b/c mine just started doing the same thing.. not really a big deal just more annoying than anything
 
If you still have a spare tire check to see if it is tight.

What do you mean by oscillating?
 
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