Loud noise under the hood
Thread Starter
Heel & Toe
Joined: Jun 2011
Posts: 19
Likes: 0
From: Wesley Chapel Florida
Loud noise under the hood
Suddenly, a large noise came from under the hood of my C5 Cpe. At idle, the noise is quite loud and increasing the RPM's causes the noise to get louder. As I said, this was a sudden noise and does not appear to be coming from the water pump, as it is not leaking and the not the alternator which is still charging. What can it be? Any help would be appreciated.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Need to get an auto stethoscope and give a listen around. I assume it idles ok? If you don't find it right away pull your DIC codes and see what is there.
Also, your can remove the belts and see if it goes away. If so then you can narrow it down by just putting one back on first.
Also, your can remove the belts and see if it goes away. If so then you can narrow it down by just putting one back on first.
Team Owner
Joined: May 2001
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From: Dear Karma, I have a list of people you missed.
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Need to get an auto stethoscope and give a listen around. I assume it idles ok? If you don't find it right away pull your DIC codes and see what is there.
Also, your can remove the belts and see if it goes away. If so then you can narrow it down by just putting one back on first.
Also, your can remove the belts and see if it goes away. If so then you can narrow it down by just putting one back on first.
Not sure what OP means by a "large noise", but maybe also taking a look-see if the HB is wobbling and/or any signs of belt edges being chewed up.
Race Director
Joined: Feb 2013
Posts: 19,864
Likes: 146
From: South East TN
Is it a squeeling noise? belts slipping or out of alignment? As previous posters have stated it is possible that the Harmonic balancer has gone bad. You can start the car and look at the balancer as it's spinning from the side. Look for any noticeable wobble or shimmy. If it is the balancer you might want to consider an upgraded version as the OEMs fail in this manner and the steering rack has to come out or be moved some to replace the balancer. You might also want to have it pinned.
You can check if it's belt squeel by rubbing a bar of soap on the underside of the belt as the engine is running. If the squeel stops when you apply the soap that is the belt in question. BE CAREFUL NOT TO GET YOUR FINGERS/LOOSE CLOTHING UNDER THE BELT WHEN APPLYING THE SOAP!
You can check if it's belt squeel by rubbing a bar of soap on the underside of the belt as the engine is running. If the squeel stops when you apply the soap that is the belt in question. BE CAREFUL NOT TO GET YOUR FINGERS/LOOSE CLOTHING UNDER THE BELT WHEN APPLYING THE SOAP!
Melting Slicks
Joined: Nov 2009
Posts: 2,922
Likes: 219
From: West Branch, MI
"Large noise" is pretty vague. If you think its in the belt area, you can do this. As stated previously, look at your harmonic balancer. If its wobbling badly, that could easily be it.
You can briefly take the belt off and start the car for a moment. If the sound goes away, then you've isolated it. Turn the car off. Try and spin each idler by hand. If it spins freely, then it's bad. Idler pulley should have a slight resistance to turning. That means its tight. If it won't turn at all, that's very bad. If it spins freely, the bearings are worn out and there's not much lubrication left in it. Hope this helps.
You can briefly take the belt off and start the car for a moment. If the sound goes away, then you've isolated it. Turn the car off. Try and spin each idler by hand. If it spins freely, then it's bad. Idler pulley should have a slight resistance to turning. That means its tight. If it won't turn at all, that's very bad. If it spins freely, the bearings are worn out and there's not much lubrication left in it. Hope this helps.
Last edited by CactusCat; Mar 18, 2014 at 11:50 AM.
Thread Starter
Heel & Toe
Joined: Jun 2011
Posts: 19
Likes: 0
From: Wesley Chapel Florida
Thank you for the input on my "Grinding" noise. I will check out the harmonic balancer and see if there is any movement. If not I will try the soap to the belt. There are no shredded areas at the edge of the belt. I have never tried to remove the serpentine belt before, how is this done? A manager at Advance Auto Parts said it was the belt tensioner pulley located above the waterpump, but the sound appears to be coming from all over the front of the engine. I wont be able to check out the car until this evening, due to being at work. Thanks again guys!
Pro
Joined: Feb 2021
Posts: 729
Likes: 317
From: Ashevile, NC
You don't say if your car is a manual or automatic. If it's a manual you don't need the flywheel holder. Put it in 6th gear and set the hand brake. It'll hold. By the way, there's no particular position for the HB, even if it has timing marks on it. They're not used on LS motors.
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Race Director
Joined: Oct 2004
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You don't say if your car is a manual or automatic. If it's a manual you don't need the flywheel holder. Put it in 6th gear and set the hand brake. It'll hold. By the way, there's no particular position for the HB, even if it has timing marks on it. They're not used on LS motors.
