kyle242gt

Hi all -

2005, stock, 74K.

It's recently started making a buzzing or whistling sort of noise, most noticeable from idle to about 2K. Sounds a little like a car with low PS fluid...

Not steering-dependent, though, and the fluid level is good. Thought it might be the serp, but spraying a little water on either side of the belt didn't make any difference. Seems to be coming from the rear of the engine or the clutch area. AC off/on didn't make any difference, so in my mind that rules out the belts and tensioners.

The noise is the same, clutch in or out, in gear or not, moving or stopped. I can (barely) detect a difference in noise when I press the clutch, which I assume is the TO contacting the PP.

About all I can figure is it's the TO bearing, since that's the only spinning thing in that area.

An LS7 clutch has been on my to-do list for a long time, so maybe this is the final straw.

I know noise complaints aren't easy to diagnose, but maybe someone has an idea...

serik21

If it's a buzzing sound I would check all your heat sheilds and make sure they are in good condition and not dried out and vibrating on something

isis

iTrader: (1)

Sounds about right but I'd think that would vary more based on clutch engagement. Is there also a pilot bearing in there? That would be more constant I think

kyle242gt

Thanks guys - appreciate the ideas.

It sure sounds like it's coming from the rotating "stuff", not something external like a heatshield.

Agree that it's puzzling that it doesn't vary more based on clutch engagement. I'm guessing that the face of the TO bearing is always in contact with the PP, and therefore always spinning vs the hydraulic assembly.

A pilot bearing ought to be silent with the clutch engaged, noisy when pushed.

hefftone

If you have a noise that goes away with your foot just barely on the clutch pedal....I would bet you'll be getting into your clutch within the next couple months. If you start to feel a pulsation in the pedal, then you'll be in there within a couple weeks.

kyle242gt

Nothing like that so far. I do have the ~2000rpm vibration, but that's been stable for as long as I've noticed it. Frankly, having to do the clutch wouldn't be the end of the world... it's just that my long-term project car is finally gaining steam and I hate to change gears right now. Plus, dragging it out of the way so I can use the lift is a PITA.

The buzz/whistle may be longer term too, hard to be 100% sure. But I think it's more recent than that.

isis

iTrader: (1)

Isn't the throw out bearing the one that bears the load while the clutch is pushed? Or am I backwards here?

LS BRAVADA

iTrader: (4)

A vacuum leak maybe ?

rand49er

Yes, and that's why I don't think that's the problem. The noise would change when the clutch pedal was depressed, and since it doesn't it must be something else.

If it's doing it without the vehicle in motion, it must be from the clutch forward. If it's from the rear of the motor, that certainly seems to narrow it down. Where is the question.

kyle242gt

The more I listen to it, the more it sounds EXACTLY like a PS pump. I'll pull the serp and see if it goes away, that's an easy one to test for.

NIKDSC5

iTrader: (10)

You're correct. The pilot bearing is always engaged. So long as the motor is spinning. When you push the clutch it is not like you're moving the input shaft. The throw out bearing engages when you push the pedal or disengage the clutch.

isis

iTrader: (1)

So if the noise is from the rear of the engine, is a rotating sound, but goes unchanged while operating the clutch wouldn't the pilot bearing be a reasonable suspect?

isis

iTrader: (1)

What? The pilot bearing and throw out bearing are both part of the flywheel/clutch assembly at the rear of the motor. and the pilot bearing load doesn't change with clutch engagement

NIKDSC5

iTrader: (10)

Yes sir!

rand49er

What?

The throw-out bearing doesn't have any load on it until the clutch pedal is depressed, so when the OP said the noise didn't change when the clutch pedal was depressed I deduced that it couldn't be the throw-out bearing. With me so far? I also stated that the problem must be from the clutch forward, and isn't the pilot bearing from the clutch forward? Still with me? If this turns out to be the PS pump, then this is from the clutch forward, and the OP was in error about the noise coming from the rear of the motor.

Did I lose you?

kyle242gt

Hi all - appreciate the input on this.

Pulled the serp, noise went away. It's still most audible from underneath the car at the clutch area, but that must just be the way the noise resonates around.

Puzzling that it doesn't vary with steering effort. But it's got to be either the PS pump, alt, or water pump. And it sounds exactly like PS noise.

Is this a common issue? I've been lurking since I got this car, and don't recall hearing of this before.

Anyone think a fluid change might help? Or just go directly to pump replacement?

Sorry for the misdirection regarding the clutch. Just shows that sometimes five minutes in the garage is better than bugging people online.

NIKDSC5

iTrader: (10)

The serp belt turns more than the ps pump. Just sayin.

kyle242gt

Agree! But what would be the likely culprit of a PS noise, the PS pump, WP, or alt?

serik21

Why don't you go to harbor freight buy a $5 stethoscope and put it on the water pump spin it by hand and do the same for the power steering pully if you can and alternator and see which bearing seems like it sounds funny. Also don't rule out the fact that it can also be your crank damper going bad. Pretty common on ls motors.

isis

iTrader: (1)

You lost me when you assumed that I thought it was the throw out bearing when I pretty clearly was steering him from there to the pilot bearing based on the exact same reasoning you are using. I just don't know how you ruled out the rear of the motor completely based on the info given to that point.

But hey, good for you both since you seem to have power steering pumps in the rear of your motor. I do not.

Carry on.