low hum from deep in the dash...?

[08HybridOK]

Just noticed this hum tonight after getting home from football game. It's a very low (quiet & frequency) 'hum'. Louder in the pass seat than the drivers. Similar to a speaker humming.

I turned off all climate controls, and radio. No change

It does seem to be a constant level, doesn't change with RPM; but as soon as I rev it gets drowned out anyway (it's that quiet; but concerning).

It also seems to be tied directly to the engine; but I can't hear it outside the cabin or in the engine bay. As soon as I turn off the engine it goes away (maybe a split second later); but it does not hum with key in the run position (but not engine running).

I ran my hand all over the dash, and under & can't feel any vibrations.
Also this is the first cold (55F) day in several months.

Any ideas what it could be? Do I need to be concerned? expensive, or just crank up the radio some more...

00 EB 5.4 90k

 

[stamp11127]

Look underneath for something touching the body or floor pan.

 

[08HybridOK]

Looked around, couldn't find anything screaming It's me, it's me.

I can not hear it outside at all, from above or below.

It sounds like a fan or pump to me; (just having changed the MECS pump on my hybrid ie a water pump) it sounds similar. It does seem to change slightly when turning on the climate control; but as soon as the fans start blowing they almost drown it out.

I vaguely remember changing some squirrel cage type fan up under the pass dash years ago. When does this fan run?

 

[stamp11127]

It might be you depending on age. I have a high pitched whine in both ears everywhere I go. But mine is from listening to Zeppelin, Hendrix, Sabbath, Nugent, Trower etc. way too loud years ago.....

Just kidding, you may have changed the blower motor since it is located up under the pass side dash.

 

[08HybridOK]

I"d say its my ears too; but my wife said she heard it... I think for now I"ll just keep the radio & HVAC on, and not hear it. I'm sure it's the blower motor & it will wait until its -10 out to die on me...

 

[rhill]

Hmmm...is it kinda like a "moan?"..Might be your idle control valve..it is on the passenger side..

 

[08HybridOK]

I had a friend listen (he works at a garage; but think he's more auto body than mechanic). He thinks its the A/C. I thought he said compressor, but that's up front where the belt is; so what is the part in the rear, near/on the firewall? Could it be making this noise?
If so, will a can or re-charge w/oil do anything, or is it a complete R&R?

 

[xJohnnyOx]

I had a similar noise when I first bought mine. After a few weeks of looking for it, I found a post that indicated it was the PCV valve. I was skeptical, but sure enough, a replacement PVC fixed the issue.

Good Luck!!!

 

[08HybridOK]

Yea, I just got some free time & started chasing it down. I finally found the same thing, replaced it & it seems to be fixed.

 

[xJohnnyOx]

Yea, I just got some free time & started chasing it down. I finally found the same thing, replaced it & it seems to be fixed.

Its amazing how much noise that PCV valve can make when it fails. Glad you got it fixed