I have a 91 camaro l98 and when it gets hot it makes a ear piercing screem

It seems to happen only when hot and below 3000 rpms

Goes away some times if you flick the gas pedal not for to long though

Seems to be coming from the middle of the engine and I tried the wd40 test and
Nothing seemed to show up

Any ideas

 

Sounds like a spun bearing to me. I had the same thing in a 4.3

 

If it was why would it stop at highway speeds and it runs good

And its only when it gets real hot like drive for 30 minutes on the freeway
Then when I get off it starts if I drive on the streets its ok

 

Hope its not a bearing. There are a couple of emission temperature controlled vacuum switches. Maybe there is leak or crack somewhere making the whistle. Pulling off a line here and there would find it.

 

Take the serpentine belt off (temporarily) when it's doing it's screaming thing and see if it goes away. Water pump bearing, power steering pump bearing, alternator bearing, tensioner pulley bearing, smog pump bearing..... all potential candidates for screaming. Start eliminating things one at a time.

A mechanics stethescope would be helpful here as well, assuming you can reproduce the problem just free-revving in the driveway.

 

Its loud so loud if you are there for 20 secs your ears will ring

It sounds like middle of the motor maybe egr? I can't pinpoint the sound
And don't want to rip it apart before I can tell where the problem is
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Its loud so loud if you are there for 20 secs your ears will ring

It sounds like middle of the motor maybe egr? I can't pinpoint the sound
And don't want to rip it apart before I can tell where the problem is


And it will do it idling only after I drive it

 

It ain't your EGR valve, firend. If it's screaming that loud it's almost certainly a bearing. But WHICH bearing is what counts. That's why I suggested removing the serp. belt temporarily to rule out front end accessories which are loaded with bearings all over the place.

 

yea its loud what other bearings could it be if not the front

and why would it get quiet over 3000rpm

 

how can i tell which bearing is bad in the front access i listened yesterday
and it sounds like my idler bearing but i have to wait tell friday to work on it

 

A mechanics stethoscope is pretty cheap. I have the $4 Northern Tool one. A length of heater hose will work in pinch. One end to your ear, touch the other to the idler. Be careful of the moving parts. It will be very obvious which one is louder.

 

ok guys removed the sep belt didnt go away what else its a super hi pitch and doesnt change pitch

 

Its not a vacuum leak if its that loud. Its not any of your front accessories if you took the belt off and it kept making the noise. If you can stick your head under the car and confirm its not coming from the trans, unfortunately its sounding grim...

 

I don't think its a bearing I started taking vacuum lines off ect and it ran like crap
But the noise went almost gone so will see I got a ported plenum I may have got a
Small crack or something

 

Try moving the stethoscope around to different areas to see where the loudest point is. Maybe try putting it against the oil pan while it is running, near the front of the block, etc. I would leave the belt off while diagnosing, but watch for overheating.

 

Is it only quieter when you create a vacuum leak? When you unhook a vacuum line and then plug the vacuum source with your finger it immeadiatly gets louder again. I'd spray some carburator cleaner around different spots. The noise should disappear briefly the second the leak gets a blast if its a manifold leak.

Figure out which has the biggest impact first. There should be a vacuum line for fuel pressure, EGR, PCV, carbon canister, brake booster, heater on your intake to each check. If for instance a heater diaphram is doing it, the noise should completely disappear when unhooked and stay gone when you plug the vacuum source with your finger to make the car run smooth again.

 

Tried that nothing I'm just reaching and checking everything

 

Are your throttle plates "singing?" It's odd, but it can happen, although I've only seen carbs do it, and only at idle never faster.

 

i dont think so it sounds mid engine such as egr i put my unported plenuem back on and will see if that fixs the problem

 

ok put my stock plenum back on and it was running good the temp was at 210 i turned off the car then i heard that damn scream as i was turning it off then when i restarted it was back!! damn this is pissing me off!

 

I spun a couple rod bearings and melted down a main in 2004 in my '89.
The car still ran and was still able to move itself down the street, which
gave me false hopes. The car did have an audible "whistle" at the middle
of the motor. But, it did not sound like a hamster.

Couple things you can try, change the oil and inspect for metal debris.
Large, small or powdered. It doesnt hurt to cut an oil filter in half either
if your not entirely sure with your findings.

I ended up adding some conventional 10w-40 oil and some lucas oil
stabilzer in the car and it seemed to quiet down.. but, the motor was still screwed...

I hate telling people their engine might be dead, so I wont.

Check your oil.

 

an audible whistle or did it sound like some one screaming!

i just changed my oil twice as i just installed a new intake so i doubt theres anything in there and like i said it ran great for 45 mins until i shut it off

 

Where are you at?

 

what do you mean where am i at =)

california, covina

 

Never know. I was talking another board member through a wiring issue and it turned out he was just a couple miles away.

 

hmm i just dont know what to do...

 

Yea, it was a whistle.. and heard knocking metal on metal contact.

Hrmm, can we get some audio?

 

i can do my best to get some audio

its a real hi pitch noise same pitch doesnt change unless i rev it then it dies down and goes to the same pitch as the rpms go back to idle

 

lol that's happened on my tbi at idle

 

how do i know if they are singing

 

If its your throttle blades, try pushing on them with a piece of small hose or screw driver (without moving them). It should dampen the vibration enough to at least make a change in pitch.

If you have a MAF sensor in the way try grabing the throttle linkage and push/pull sideways on it.

 

i think its now a vacuum leak as if i barely press the accel pedal the sound dies down and if i tap it again it will go back to the super load pitch

 

here is the sound from inside the car as its too loud to record outside

the first 2 secs are the door

http://www.friendswapmeet.com/200811...28Ringtone.mp3