2007 Tahoe rattle

[Cindysue422]

2007 Tahoe
Not sure where this noise is coming from. Here's what we've done so far:
**Originally thought it was lifter tap, added atf to engine for it to work its magic, only wishful thinking. Removed valve cover and rocker arms had no slack so we eliminated this.
**Got underneath and thought it was a faulty cat. One was broken up already so we gutted both to maybe fix it? Nah, this was only muffling the noise, now it's way worse as heard in the video.
**Thought maybe the flexplate had busted around the center? Dropped the transmission today and flexplate is perfect.
This is my daily and I don't want to give up on her yet. I'll take and and all suggestions!!

 

[Fless]

Could the starter not be releasing all the way, and the pinion gear tapping on the flexplate?

 

[solli5pack]

Sound like an exhaust leak to me...should be easy to find since it's so loud..

 

[OBSandaNNBS]

2007 Tahoe
Not sure where this noise is coming from. Here's what we've done so far:
**Originally thought it was lifter tap, added atf to engine for it to work its magic, only wishful thinking.

Does it change with engine speed?

Sound like an exhaust leak to me...should be easy to find since it's so loud..

This was my first thought too.

Give her a rev and tell us what happens.

 

[solli5pack]

Also run it with the belt off...it it goes away then you know it's one of thr accessories...

 

[Cindysue422]

Does it change with engine speed?


This was my first thought too.

Give her a rev and tell us what happens.

Not an exhaust leak. It's not rhythmic with RPM increase. 100% wouldn't have dropped the transmission in the driveway without eliminating that possibility. Dang, should have put that in the original post.

 

[Cindysue422]

Could the starter not be releasing all the way, and the pinion gear tapping on the flexplate?

No marks on the flexplate showing that anything was dragging in it. No scrape marks on the torque converter either.

 

[solli5pack]

Not an exhaust leak. It's not rhythmic with RPM increase. 100% wouldn't have dropped the transmission in the driveway without eliminating that possibility. Dang, should have put that in the original post.

So it doesn't change at all with RPM? If not check out the cooling fans....

 

[Cindysue422]

So it doesn't change at all with RPM? If not check out the cooling fans....

These are electric fans.

 

[j91z28d1]

man that's a really fast noise for idle speed.

huh.

and it got. louder after gutting the cat?

it's almost got a tin sound to it.. I got nothing for this one. I think it might be good to rule out the starter drive.

 

[Cindysue422]

Also run it with the belt off...it it goes away then you know it's one of thr accessories...

R/R the belts and it went away. What the heck?!

 

[j91z28d1]

you put the belt back on and it isn't doing it now?

 

[solli5pack]

A worn or low quality belt can make that type of noise but I would think the noise would change with RPM'S

 

[Fless]

Same belt, or new put back on?

Did you remove and replace both the main and the A/C belts with new?

 

[OBSandaNNBS]

This is blowing my little mind. Was the belt shredded?

 

[Doubeleive]

R/R the belts and it went away. What the heck?!

"It's not rhythmic with RPM increase" means it is not rotational noise and is likely something else external to the engine.
so your suspect is bolt on, r&r ing the belts may have temporarily released some type of pressure on whatever is failing, if it is working now great but keep an eye on it.
ac pumps are known for self destruction, over time or by rpm. might be quiet at idle but revving it up then reveals noises.
if the noise returns grab a $10 mechanics stethoscope at the autoparts store and poke around the bolt on's, it should be easy to find.

 

[solli5pack]

These are electric fans.

Yes. And they spin independent from RPM's. Thats why if the sound is not RPM related they would be a possible source...

 

[lspann3525]

power steering pump?

 

[Rocket Man]