Help Me Diagnose This Sound.....

[Rob1]

Hello all....

 

07 Avalanche 5.3 with just over 100K miles.....

 

Here'e a link to the YouTube video I shot this morning. Just wondering if the sound is lifters or something else......

 

07 Avalanche cold engine sound

 

The sound will quite down / disappear once the engine has warmed up.

 

Any help would be appreciated.

 

Cheers

[ozman2005]

Can't help you a whole lot with the sound, but I wanted to commend you on the engine compartment. I would have never guessed your truck had over 100K on it. Looks great!

 

One guess I have is an exhaust leak. Could be completely wrong, but I'm basing it on your comment that the noise goes away or quiets down as the engine warms up. As the manifolds warm up they expand against the gaskets and seal the leak. Maybe check for any loose manifold bolts or obvious cracks. Good luck.

 

Ozzie

[vettelovralexand]

That sounds like piston slap to me.

[4wd]

looks like coming from the bottom part of the engine...exhaust manifold leak should sound more sharp noise, but it's worth checking as mentioned above...

[dlewis1111]

That sounds like piston slap to me.

 

+1

[Slabi]

That sounds like piston slap to me.

 

+1

 

 

Sounds like a Vortec to me.

[Rob1]

That sounds like piston slap to me.

 

+1

 

 

Sounds like a Vortec to me.

 

 

otherwise - normal?

[Hoytal1]

Mine had the same noise, took it to the dealer, replaced a catalytic converter, problem solved! I really thought it was an internal problem, but no. No codes, either.

[Rob1]

Mine had the same noise, took it to the dealer, replaced a catalytic converter, problem solved! I really thought it was an internal problem, but no. No codes, either.

 

Catalytic converter....hmmm....what's GM emissions warranty?

[Silverado4x4]

Thats not piston slap, sounds like from the vid is a exhaust leak. Take it to an exhaust shop and tell them you think you have a exhaust leak, they should check it for free.

[8.1HD/ALLISON]

My vote is for the piston slap, but hearing on a video and hearing in person is two different things.

[Rob1]

Thats not piston slap, sounds like from the vid is a exhaust leak. Take it to an exhaust shop and tell them you think you have a exhaust leak, they should check it for free.

 

 

Problem is once it warms up (5 mins) the noise is gone. I would have to leave the truck with them so they could test when cold.

 

With vacuum leak will the noise stay even when warm?

 

Cheers

[exracer]

Rob....does sound change or go away if you drop it into drive or R..?....

[Rob1]

Rob....does sound change or go away if you drop it into drive or R..?....

 

 

No....it's there until warmed up......in this current cold weather if I let her idle it's about 4 mins or so.....

 

Once warmed up no sound.

 

Cheers

[[email protected]]

Another vote for piston slap.