Vibrating/Grinding Noise from top of engine

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

cjp24

TYF Newbie
Joined
Mar 17, 2020
Posts
3
Reaction score
1
I have an 07 Tahoe 5.3L V8, and about a month ago I started noticing a quiet noise when slowing down to a stop, when the engine returned to idle, for a brief second it sounded as though maybe a pulley was bad or AC clutch not disengaging all the way. As two weeks passed, it started lasting longer (up to maybe 10 seconds after stopping and typically causing an RPM fluctuation/idle down as well). Then it started briefly making the noise when turning the car off as well. Then after a week of that, it started making the noise when turning the car on after it was already hot for a brief second. At first it was worse when the car was cool but now it seems to not matter the car temp or outside temp. I removed the AC belt and it still makes the noise, checked pulleys and all feel fine, felt lines and plastic and clips on top of motor and nothing felt loose or rattling. Finally caught the noise on video, will try to figure out how to post. Also able to find that the noise seems to be coming from the top of the engine behind the throttle body. Any one have any ideas?? I'm at a loss and it is driving me crazy

link to sound on YouTube:
 
Last edited:

wjburken

Supporting Member
Joined
Dec 26, 2017
Posts
9,244
Reaction score
23,940
Location
Eastern Iowa
I have an 07 Tahoe 5.3L V8, and about a month ago I started noticing a quiet noise when slowing down to a stop, when the engine returned to idle, for a brief second it sounded as though maybe a pulley was bad or AC clutch not disengaging all the way. As two weeks passed, it started lasting longer (up to maybe 10 seconds after stopping and typically causing an RPM fluctuation/idle down as well). Then it started briefly making the noise when turning the car off as well. Then after a week of that, it started making the noise when turning the car on after it was already hot for a brief second. At first it was worse when the car was cool but now it seems to not matter the car temp or outside temp. I removed the AC belt and it still makes the noise, checked pulleys and all feel fine, felt lines and plastic and clips on top of motor and nothing felt loose or rattling. Finally caught the noise on video, will try to figure out how to post. Also able to find that the noise seems to be coming from the top of the engine behind the throttle body. Any one have any ideas?? I'm at a loss and it is driving me crazy
Welcome to the forum from Iowa, CJ.

Most folks find it best to upload videos to YouTube and then share the link here.

Get that video posted and see what the knowledgeable folks here can do for you.

One thing you could do is take the Serpentine belt off and run the engine for a short time to see if the noise remains or goes away. If it remains, you can definitely rule out the belt driven pulleys.
 
OP
OP
C

cjp24

TYF Newbie
Joined
Mar 17, 2020
Posts
3
Reaction score
1
Welcome to the forum from Iowa, CJ.

Most folks find it best to upload videos to YouTube and then share the link here.

Get that video posted and see what the knowledgeable folks here can do for you.

One thing you could do is take the Serpentine belt off and run the engine for a short time to see if the noise remains or goes away. If it remains, you can definitely rule out the belt driven pulleys.

I will try running without belt on tomorrow and see, I have edited the post to include sound from YouTube, thanks!
 

OR VietVet

Multnomah Falls
Joined
Oct 8, 2014
Posts
17,221
Reaction score
26,246
Location
Willamette Valley
Yes, welcome to the forum from Oregon.

So, you only took one belt off? Why not the other?

You may have a vacuum leak at the back there that is getting progressively worse.

If you can catch it, the best way to find a noise is with a mechanic's stethoscope.
 
OP
OP
C

cjp24

TYF Newbie
Joined
Mar 17, 2020
Posts
3
Reaction score
1
Yes, welcome to the forum from Oregon.

So, you only took one belt off? Why not the other?

You may have a vacuum leak at the back there that is getting progressively worse.

If you can catch it, the best way to find a noise is with a mechanic's stethoscope.

I took both off to check the belts and feel/spin pulleys and then reinstalled the main drive belt and ran it with AC belt off. Simply did not think to run it with both belts off briefly.
 

swathdiver

Full Access Member
Joined
May 18, 2017
Posts
18,693
Reaction score
23,921
Location
Treasure Coast, Florida
I took both off to check the belts and feel/spin pulleys and then reinstalled the main drive belt and ran it with AC belt off. Simply did not think to run it with both belts off briefly.

Can I infer that after doing this the noise was still there CJ? Listened to the video, it's a new one for me. If repeatable, I would get a long extension or mechanic's stethoscope and touch one end to your ear and the other to various parts of the motor while someone starts and kills the motor until found.
 

91RS

Full Access Member
Joined
Nov 15, 2009
Posts
2,323
Reaction score
1,679
Location
GA
Oil level full? Almost sounds a like a lifter bleeding down and makes noise until it gets pumped up with oil/pressure.
 

Forum statistics

Threads
125,840
Posts
1,756,078
Members
87,736
Latest member
Our2023tahoe

Latest posts

Top