New engine whistle/whine - ZR-1 Net Registry Forums

mlipmd · 12-23-2023

I changed my oil/filter today and then ran the engine to circulate it around before checking the level again, and heard this high pitched whistle/whine when the hood was open. Don't really hear it with the hood closed. First I thought it may be a vacuum leak, then I thought maybe a pulley bearing or similar. It's loudest I think in the left front of the engine. The pitch rises with increased engine speed. The car runs perfectly, no problems at all. Any thoughts or suggestions or can I just ignore this for now and wait for something to happen?
I'm having trouble uploading a mov file because the site won't take it and I don't know how to edit it to a shorter version or convert it to something else so I can't give any more clues as to the whistle sound.
Thanks anyway.

Jagdpanzer · 12-23-2023

Suggest try slacking the belt tensioner with the engine idling and see if that makes any difference

Sent from my iPhone using ZR-1 Net Registry

mlipmd · 12-24-2023

This morning that whistle is only heard at dead slow idle, as soon as you rev up the engine even slightly it disappears. So I think it's related to the belt, maybe exacerbated because of the cooler temperature. I really can't get anything into the tensioner to try and loosen it a bit, my breaker bar is too lose in the hole in the center of the pulley. For now I'm just going to keep an eye (or an ear) on it as I don't think it's anything significant. Thanks.

Mikey · 12-24-2023

I would guess it?s a pulley bearing going bad

Z51JEFF · 12-27-2023

Quote:

Originally Posted by mlipmd

This morning that whistle is only heard at dead slow idle, as soon as you rev up the engine even slightly it disappears. So I think it's related to the belt, maybe exacerbated because of the cooler temperature. I really can't get anything into the tensioner to try and loosen it a bit, my breaker bar is too lose in the hole in the center of the pulley. For now I'm just going to keep an eye (or an ear) on it as I don't think it's anything significant. Thanks.

The correct ratchet should fit in the tensioner no problem,providing the square bore hasn't been raped by some hack.

mlipmd · 12-29-2023

If it were a pulley or other bearing going bad then why would the whistle only occur at dead low idle and not increase in loudness or pitch with increase in engine rpm?

Mikey · 12-29-2023

Your original post said it increases in pitch with engine speed. High pitch noises are most often caused by metal on metal. Load and rpm on the pulley can change whether or not it makes the noise. Think about how a door hinge can squeak when opened slowly but if you open it rapidly it doesn?t make noise. I chased a very similar issue as you described for over a year that I was sure was a weird whistle in an aluminum intake pipe on my LS swap ?64 C2. The noise came and went under various rpm and load. Then the bearing completely seized and came out of my tensioner.

mlipmd · 12-30-2023

I'll have to make up a mechanic's stethoscope and try and track down the source of the whistle. It's very faint now only at idle and rapidly drops in pitch as it fades as I turn the engine off. Right now I think it originates from the front driver's side of the engine.
I also just started to get the HVAC blinking light from code 09 (low Freon) again, but it's too cold (in the 50-60 range) to refill the system. So right now the faint whistle could be from the water pump or AC clutch or something else in that area. Like I said, I need my stethoscope to get a better idea, or just wait for something maybe to go bad in the future.

mlipmd · 12-30-2023

Can't hear anything with a stethoscope 'cause everything is rotating and you can't get on it to locate a noise.
I have now a 1/2" breaker bar that should fit the tensioner, I think I was using a 3/8" which is too small for that square socket. And if the noise disappears if I loosen tension on the belt, what does that mean? It still could be a pulley or the belt or anything driven by the belt, so that's no help to locate the source of the whistle.
And now my HVAC light is no longer flashing when I turn the unit on.
Friggin car. But I should be glad that it runs well.

Mikey · 12-30-2023

To eliminate belt squealing as a potential source simply spray or even just dribble water on the belt when you hear the noise. If it immediately quiets and then noise comes back then it is belt squealing.

Otherwise I think it means bearing going bad if you are able to affect noise by playing with belt tension and have otherwise eliminated the belt as the culprit

12-23-2023	#1
mlipmd Join Date: Mar 2021 Location: Crawfordville, FL Posts: 198	New engine whistle/whine I changed my oil/filter today and then ran the engine to circulate it around before checking the level again, and heard this high pitched whistle/whine when the hood was open. Don't really hear it with the hood closed. First I thought it may be a vacuum leak, then I thought maybe a pulley bearing or similar. It's loudest I think in the left front of the engine. The pitch rises with increased engine speed. The car runs perfectly, no problems at all. Any thoughts or suggestions or can I just ignore this for now and wait for something to happen? I'm having trouble uploading a mov file because the site won't take it and I don't know how to edit it to a shorter version or convert it to something else so I can't give any more clues as to the whistle sound. Thanks anyway.

12-23-2023	#2
Jagdpanzer Join Date: Apr 2007 Location: Northern VA Posts: 2,644	Re: New engine whistle/whine Suggest try slacking the belt tensioner with the engine idling and see if that makes any difference Sent from my iPhone using ZR-1 Net Registry __________________ Phil Wasinger 1994 Torch Red ZR-1 WAZOO Member George Braml Intake

12-24-2023	#3
mlipmd Join Date: Mar 2021 Location: Crawfordville, FL Posts: 198	Re: New engine whistle/whine This morning that whistle is only heard at dead slow idle, as soon as you rev up the engine even slightly it disappears. So I think it's related to the belt, maybe exacerbated because of the cooler temperature. I really can't get anything into the tensioner to try and loosen it a bit, my breaker bar is too lose in the hole in the center of the pulley. For now I'm just going to keep an eye (or an ear) on it as I don't think it's anything significant. Thanks.

12-24-2023	#4
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 299	Re: New engine whistle/whine I would guess it?s a pulley bearing going bad

12-29-2023	#6
mlipmd Join Date: Mar 2021 Location: Crawfordville, FL Posts: 198	Re: New engine whistle/whine If it were a pulley or other bearing going bad then why would the whistle only occur at dead low idle and not increase in loudness or pitch with increase in engine rpm?

12-29-2023	#7
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 299	Re: New engine whistle/whine Your original post said it increases in pitch with engine speed. High pitch noises are most often caused by metal on metal. Load and rpm on the pulley can change whether or not it makes the noise. Think about how a door hinge can squeak when opened slowly but if you open it rapidly it doesn?t make noise. I chased a very similar issue as you described for over a year that I was sure was a weird whistle in an aluminum intake pipe on my LS swap ?64 C2. The noise came and went under various rpm and load. Then the bearing completely seized and came out of my tensioner. Last edited by Mikey; 12-29-2023 at 11:39 PM.

12-30-2023	#8
mlipmd Join Date: Mar 2021 Location: Crawfordville, FL Posts: 198	Re: New engine whistle/whine I'll have to make up a mechanic's stethoscope and try and track down the source of the whistle. It's very faint now only at idle and rapidly drops in pitch as it fades as I turn the engine off. Right now I think it originates from the front driver's side of the engine. I also just started to get the HVAC blinking light from code 09 (low Freon) again, but it's too cold (in the 50-60 range) to refill the system. So right now the faint whistle could be from the water pump or AC clutch or something else in that area. Like I said, I need my stethoscope to get a better idea, or just wait for something maybe to go bad in the future.

12-30-2023	#9
mlipmd Join Date: Mar 2021 Location: Crawfordville, FL Posts: 198	Re: New engine whistle/whine Can't hear anything with a stethoscope 'cause everything is rotating and you can't get on it to locate a noise. I have now a 1/2" breaker bar that should fit the tensioner, I think I was using a 3/8" which is too small for that square socket. And if the noise disappears if I loosen tension on the belt, what does that mean? It still could be a pulley or the belt or anything driven by the belt, so that's no help to locate the source of the whistle. And now my HVAC light is no longer flashing when I turn the unit on. Friggin car. But I should be glad that it runs well.

12-30-2023	#10
Mikey Join Date: Jul 2020 Location: Nashville TN Posts: 299	Re: New engine whistle/whine To eliminate belt squealing as a potential source simply spray or even just dribble water on the belt when you hear the noise. If it immediately quiets and then noise comes back then it is belt squealing. Otherwise I think it means bearing going bad if you are able to affect noise by playing with belt tension and have otherwise eliminated the belt as the culprit