jbann72

My car has done this two or three times now. When I start it up it makes this noise for about half a block of driving or about a minute of idling. When driving, once I start accelerating it goes away but comes right back when I let off the gas. Again...it only does this for a minute max then goes away. When it happened yesterday I got right out and recorded it. Sounds like a large bearing to me. Throttle bearing? Alternator? what do you guys think? I cannot duplicate it and it definitely doesnt happen but maybe one in 20 starts.



http://www.youtube.com/watch?v=Dl7QKwaQjHY

Anthony Williams

iTrader: (3)

First if your car is a 2000 it must be a very early one because 2000 LS1 began useing the electronic throttle with no EGR which yours has (that black thing with the metal tube going in th intake attached to the pass head), and the LS6 style intake with no EGR provision (hole). That noise I belive is your air pump going bad(req. with EGR) it is in the area behind the driverside head light.

jbann72

It's not the air pump. I took it by force fed performance yesterday and my guy there thought the same thing. He hooked up the tech tool and turned on just the air pump and its working properly. I still think it sounds like a throttle bearing.

jbann72

bump.

wssix99

iTrader: (5)

I wonder if its one of your idler or tensioner bearings. You should be able to take the belts off and turn the pulleys by hand. If it feels or sounds like a meat grinder, it needs to be replaced.

You can also get a mechanics stethoscope to confirm while everything is running.

StealthB4C2002

take belt of an start, for a few seconds. .that will tell ya quick

sjsingle1

iTrader: (1)

MAF bushing for sure

jbann72

Ive taken the belt off and started it but it doesn't make the noise but every 20 or even 30 starts. I can't reproduce it. Im going to keep my scope in the back seat so I have out handy next time it starts. I just figured someone would know exactly what it is just from the noise. You can hear in the video that it just stops instantly after about 20 seconds...makes it really hard to diagnose.

jbann72

Any other ideas here from anyone? Still havent been able to reproduce the noise. I know someone on here will be able to watch the video and know exactly what it is.

Open to all comments/suggestions.

Elthesh

iTrader: (1)

Really, if it only happens once every 20-30-40 times or whatever, having the tech turn the air pump on once or twice and ruling it out, doesn't rule it out at all. That's not to say it IS your noise source, but...

I would also look at the alternator, power steering pump, and main idler bearings first. However, that whine/howl does not sound like any bad bearing I've ever heard. If the idler/tensioners haven't been replaced in a long time, or ever, I would replace those based on the scientific theory of "Just cuz".

Another thought, and this is just a random one, it kinda sounds like something I heard on a 3rd gen TPI setup once where the throttle plates were somehow messed up causing a howl. Maybe it was the throttle shaft bearings, I forget what the actual cause was.

I'd still look at that air pump though. Plus being as those things are one of the first to get tosed in the trash due to noone wanting them, if they can get away with it, should be a dime a dozen to get a cheap or no cost replacement to test.

O2Form

Its the air pump.....forget about it.

oddwraith

iTrader: (1)

I'm saying it's the AIR pump. More specifically, when the check valves become plugged (black ones on either side of engine bay) they can cause this sound. I don't know how he would have ruled it out like that

AwsmGy

iTrader: (4)

I'm also going to agree that it's the air pump. The sound lasts about as long as the pump is usually on. Just remove the thing and throw it in the garbage.

Braunbeck

iTrader: (4)

Allegedly the AIR pump was removed from my car, the intake was capped, the headers capped, the pumping was all gone and the pump remained for another few days. I was driving next to a curb and the type of high pitch whirling sound came on. It annoyed the hell out of me, once it took the pump off I never heard it again. My guess is the AIR/EGR

JKB315

iTrader: (9)

Did you figure this out? Mine is making a identicial sound and my air pump is gone. I replaced one idler pulley. My brother said my power steering has some vibration so I am think this is the problem.

TwicePipes

That is def the air pump making that noise.

No question about it.

JKB315

iTrader: (9)

Guess mine is the air pump's ghost then.