Crimsonnaire

iTrader: (1)

Hi.

I recently started to hear a buzzing whine coming from under the hood, within the viscinity of the intake manifold. The sound alternates in volume and pitch, but is pretty consistent in sounding like bees. I confirmed it's not coming from the power steering. I never ever encountered tihs before, and the only thing I did differently before this happened (about 20 mins before) was fill the gas tank up to full.

Can somebody please give me an idea as to what likely causes this sound?

Thank you and Happy Holidays.

ghardester

Check the serpentine belt to see if it's frayed or cracked. Look for something loose like the clamps on the air lid.

Crimsonnaire

iTrader: (1)

Oh, yes. I checked the belt section when I inspected the power steering, and I could hear it clearer and louder as I slowly moved up towards the intake section. The only conclusion I was able to make was that it's coming from somewhere around the top of the engine. If not the intake manifold, then somewhere within the assembly under the schrader rail. Aw crap, could some debris have gotten through the filter and into the intake? The fuel injecters couldn't make this sound, could it?

ghardester

Take off the air lid and make sure the MAF screen doesn't have something on it. And please don't say you are one of those that took the screen out!

Crimsonnaire

iTrader: (1)

Are you talking about the metal piece that sits in the tubing directly in front of the intake manifold? I'm afraid I don't have that thing. I didn't take it out. The previous owner must've taken it off.

Where could debris get to if it gets past this screen? What could one use to suck it out?

samson_420

iTrader: (1)

It also might be the IAC.

Take off the throttle body with the complete air lid and MAF. Take a close look at everything in the components.

ghardester

Yeah, the screen on the MAF, which is right in front of the throttle body is the last line of defense to keep stuff out of your engine. Some guys think they are somehow going to gain a fraction of a fraction of a little horse power
by removing that screen. Most things that make it past your air filter would get caught by that screen. Air filters and lids don't always seal up completely. Foam strips on the lid seal can come off and there is no stoping it. To each his own way...

I'm not even sure I'm pointing you in the right direction to find your noise, just offered a place to look. Don't panic, be methodical, and eliminate the possibles and you will end up with the probables.

And if you ever have an occation to replace your MAF unit, leave the screen in.

Crimsonnaire

iTrader: (1)

OK, I gave it a much closer inspection this time, and the whine is definitely coming from the throttle body area. I also got to experiment a little, and determined that the whine apparently responds to throttle. When I start to give throttle, the sound starts to dissipate immediately and doesn't come back until it gets back to idle. Is it likely the IAC valve? Or is there something else by the throttle body that could whine?

ghardester

Is this a 'ported' trottle body? I ask since your MAF has been descreened. Maybe it is the throttle blade itself vibrating inside the body? Make sure you don't have anything loose like the clamp on the bellows or something inside the air lid.

Did you follow samson 420's advice and take the lid off and look at the trottle? Taking all that off including the throttle body is no big deal.

Crimsonnaire

iTrader: (1)

Another update: Now I've determined that the sound is coming from below the throttle body. Somewhere between the TB and big pulley directly beneath it. Also, I've noticed a pulsing whistle when the engine is idling down after a high acceleration, like a 'woop-woop-woop,' the speed of which also corresponds to the engine RPM. Being in the driver seat when I hear this whistle, I can only assume it's coming from the same spot. Last, I thought I felt an unusual amount of hot hair blowing out of the frontal area (by the pullies)... Maybe a broken fan or hose?

Oil pressure and coolant temperature along with engine idle is steady. Nothing wrong detected from the gauges.

Crimsonnaire

iTrader: (1)

It's starting to become clear that the problem is not from the throttle body, which means that I probably won't be able to tinker with it myself.

Crimsonnaire

iTrader: (1)

What's a "ported" throttle body?

I didn't find anything loose by the throttle body. Here are a couple pics:

ghardester

A 'ported' throttle body is one that has had metal shaved out from the inside to make the air flow better, supposedly. I can't really tell if your's is but I think so.

If you didn't find anything loose then spray some MAF cleaner on those wires while you have it all off and put everything back.

biggb1783

are u positive its in the tb assembly, i have had pcv valves rattle badly enough to think its buzzing.

Sharpe

iTrader: (7)

If you have a friend with an LS1, swap Tb's real fast.

I doubt yours has been ported since you still have the LS1 intake.

Ryanmgaspard

iTrader: (6)

Another option, check your power steering pump and its fluid. If the fluid is dark red/brown it needs to be changed... try Lucas power steering. Mine did the same whine and the power steering pump threw the noise all over the place because of the serpentine belt its attached to. My pump needed to be replaced with all the lines. Also, it was wasn't loud when I turned the wheel but it was a bad pump.