Mystery noise.

[MrNoodly]

This is not the kind of thing I want to face in a newly acquired used van. (2007 Express, 4.8L V8)<br><br>I was driving along, doing about 40 MPH on a city street, when suddenly, out of nowhere, there was a sound from somewhere in the general direction of the engine compartment. (My hearing is kind of bad, so I have a hard time detecting the direction sound is coming from.) The sound was part whistle, part growl, with a rising pitch. It lasted about 5 seconds. I thought maybe a cooling hose had ruptured, but there was no dripping fluids. Maybe it was AC refrigerant leaking. I didn't have the AC on, but who knows. I turned on the AC and it worked fine. Had the serpentine belt let go? No, it was fine. A spinning bearing? If so, crap.<br><br>So I drove again, monitoring the gauges. Everything looked normal.<br><br>Then a couple of days later, the same noise. I had driven only a couple of miles.<br><br>And then a third time, today.<br><br>Now, because of my bad sound location abilities, I got wondering if the noise was actually coming from my newly installed audio system. Some kind of short or interference or other ghost in the machine?<br><br>So I guess it's time to have a mechanic check it out. The way these things go, though, it might not make the noise for him. Or he might be familiar with it. "Oh yeah, that's _________________________."<br><br>Any thought form the forum?

 

[yesican]

Could it be an auxillary fan kicking in?&nbsp; One that runs when engine temps get to be a certain degree.&nbsp; <br><br>Rae

 

[anm]

Sounds like it might be a bearing, and idler pulley maybe?

 

[Zil]

there are many sources of whistle-growl. Intermittent suggest vacuum leak if you checked the other stuff you mentioned. What CD were you playing?

 

[highdesertranger]

mr noodly it never does it when the mechanic is looking at it. ha ha. does the pitch change with engine speed? without hearing it I only guessing here, but I tend to agree with anm, kinda sounds like a bearing going south. highdesertranger
shouldn't this be over in the new mechanical issue area?

 

[MrNoodly]

It hasn't happened in many months, but it has also happened when it was parked with the engine turned off. So far the van hasn't broken down. Still a mystery.

 

[akrvbob]

Mr Noodly. look at your post count!!

I'M GOING TO HAVE TO BAN YOU!!

Say hi to Mark and Donna for me! Tell them they had better plan to join is for the holidays. I'll buy the ham!
Bob

 

[MrNoodly]

When I left them today, I told them I'd see them at RTR. They said they wouldn't miss it. They just aren't sure what they want to do between the end of their hosting job and RTR.

 

[SternWake]

If it happened when parked and the engine off, it is likely the vaccuum accumulator for changing the hvac vents from floor to dash to defrost.

Nothing to stress out about. Do the vents work properly when you change their locations?