Sounds like it only does it after the exhaust cools down a bit. Back to flexpipe. As it gets hotter, the metal expands, mostly sealing the crack.

Usually caused by a worn engine mount. Look through the access hole (for the belt tensioner bolt) in the passenger wheel well. If the bolt is sitting low in access hole, your front mount is toast.

 

Doesn't do it when it's cold, and again it doesn't sound like an exhaust leak, it has on owwww..rising in pitch sound to it.This definitely like a bearing howl.. But, I am having the flex tube checked tomorrow.

SteveT.

 

1. Flex pipe
2. Throw out bearing
3. Gremlins
4. Wild animal living in the engine compartment

That's all I've got in the "Wild Guess" department. Without a video or sound bite that's about all we can do is guess.

 

You could remove the Serpentine Belt for a bit, see if it still howls. You'd lose the alternator and air conditioning. That would test both of those bearings, as well as the tensioner.

 

Belt idler bearing? Or a/c compressor? Or alternator? You could try taking the belt off temporarily.

[edit] LOL, Looks like RJ_RS_SS_350 beat me to it!

If you ever answered if the pitch varies in proportion to engine RPM, I missed it.

 

#1.. nope had it checked today
#2..nope, does it with car in neutral no foot on clutch.
#3..Could flippen be!!
#4..See #3!!

SteveT.

 

Somewhat.. And yes, I am going to try that.

I did take the car in today to have the flex tube checked and no that wasn't it. The tech that checked it drove it and he didn't hear it, but seems to think it might be the water pump. And it only did it one time today, and of course it was while leaving the shop!!! I'm going to continue to drive it and if it gets worse, then maybe I/we can figure out what it is!

SteveT.

 

Is the coolant temp acting right? Could be the pump impeller is broken.

 

Yup, steady as can be, and as hot as it is here, it would show. And the AC will freeze you out also!!

SteveT.

 

I had a bad balance chain tensioner. (The balance chain of course runs the water pump as you know.) The ratchet mechanism (for lack of a better description) upon inspection seemed sticky or worn and not holding position. No reason to thick the hydraulic function wasn’t working just fine and would provide tensioning force once the oil pressure pumped it up.

Kinda takes us back to timing chain. Most people don’t describe chain noise as a roar but maybe a video or sound would help you get other opinions. Also there’s been discussion on another forum about Cobalts that are making a noise that sounds like a the timing chain for a short period of time called start up even though the timing chain is proved tight.

Edit - in one case the problem proved to be a defective brand-new timing chain tensioner installed in the course of a chain job. Replacing it with the AC Delco tensioner fixed it. No mention of whose kit was used.

I would think a problem with lifters or sticky valves or other valve train problems would be more of a clatter than a roar.