Bad C5 Harmonic Balancer?
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4th Gear
Joined: Jan 2025
Posts: 4
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Bad C5 Harmonic Balancer?
I’ve been getting this high pitch whistling sound almost with a little bit of bird chirping sounds too. Checked it out and maybe see a little wobble in the harmonic balancer. Does this need to be replaced?
https://m.youtube.com/shorts/e8OBVftN3hA
https://m.youtube.com/shorts/e8OBVftN3hA
Last edited by colbyJc5; Jan 29, 2025 at 12:50 AM.
Pro
Joined: Dec 2014
Posts: 682
Likes: 276
From: Cincinnati Ohio
1. Take a white paint pen or something similar and paint a white mark from the inner steel to the outer steel of the balancer. Watch the white mark over the next days or week and see if the pulley portion moves relative to the inner portion.
2. Remove the serpentine belt and see if the noise goes away.
3. If the noise went away, replace the belt.
Race Director
Joined: Mar 2007
Posts: 11,338
Likes: 8,491
I had the bad balancer problem with my C5 at around 85000 miles. It sounds exactly like a squealing belt. I don't recall that it had noticeable wobble. Before I knew what it was,, I thought it was the belt. At first it was intermittent, then it got worse. If it is that, it needs to be replaced before it fully separates and causes major damage.
I want to add - the reason it sounds like the belt squealing is because it is the belt squealing. It is (or was in my case) caused by the harmonic balancer starting to fail. Apparently the resulting mis-alignment causes the belt to squeal. It can be quieted down temporarily by spraying water on it. And, as I said, the wobble to me was not noticeable or obvious, but it was enough to make the belt squeal. Belt dressing can also quiet it down, but if it is caused by the harmonic balancer, it will only be temporary, and it masks the issue.
I want to add - the reason it sounds like the belt squealing is because it is the belt squealing. It is (or was in my case) caused by the harmonic balancer starting to fail. Apparently the resulting mis-alignment causes the belt to squeal. It can be quieted down temporarily by spraying water on it. And, as I said, the wobble to me was not noticeable or obvious, but it was enough to make the belt squeal. Belt dressing can also quiet it down, but if it is caused by the harmonic balancer, it will only be temporary, and it masks the issue.
Last edited by Andybump; Jan 29, 2025 at 09:06 AM.
Safety Car
Joined: Dec 2015
Posts: 3,947
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From: Canada
The simplest recommendation when this question is asked:
1. Take a white paint pen or something similar and paint a white mark from the inner steel to the outer steel of the balancer. Watch the white mark over the next days or week and see if the pulley portion moves relative to the inner portion.
2. Remove the serpentine belt and see if the noise goes away.
3. If the noise went away, replace the belt.
1. Take a white paint pen or something similar and paint a white mark from the inner steel to the outer steel of the balancer. Watch the white mark over the next days or week and see if the pulley portion moves relative to the inner portion.
2. Remove the serpentine belt and see if the noise goes away.
3. If the noise went away, replace the belt.
how about those pulleys and idler that you can’t heard without the belt on
Melting Slicks
Joined: Mar 2023
Posts: 2,916
Likes: 1,675
From: North Coast
I don't hear anything. The balance looks ok but the camera moved so much.
It also can be attributed to glazing on pullies. and also alternators will make noise too.
Remove the belt or even put a little water on the belt to see if the sound changed. New belts on old pullies can squeak on the old rubber left behind by the old belts. V belts were bad for this and new serpentine belts it still happens.
Alt the pulley, bearing and clutch if equipped in the unit can do this.
It also can be attributed to glazing on pullies. and also alternators will make noise too.
Remove the belt or even put a little water on the belt to see if the sound changed. New belts on old pullies can squeak on the old rubber left behind by the old belts. V belts were bad for this and new serpentine belts it still happens.
Alt the pulley, bearing and clutch if equipped in the unit can do this.
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I marked mine with a witness mark a couple years ago. would check it every now and then and it happened. marks were about 3 inches apart. I had the chirp. i'm about half way done now and will finish this spring. it's cold here and no heat in the garage.