What's this noise I hear?

[KMeloney]

Hey all,

Ok, I have to ask, 'cause it's just kind of annoying, and I really don't know what it is that I'm hearing.

We all know that the 5.8s (at least) are programmed/geared such that the engine lugs more often than not, especially going up a hill, and when you don't stand on the gas pedal. Well, under those conditions, when the truck is really in too high of a gear, and the engine lugs, I can hear a "clackle clackle clack" (not really a high pitched metalic "clink," but a slightly lowered pitched "clack") coming from the engine (or the engine bay area, or just under it).

It sounds as if two pieces of aluminum are hanging down and knocking together. That's the best way to describe it. It's not a musical tone.

Again, it's only under load, when the engine is lugging.

Any thoughts on the matter? Even if it's "normal," I'd like to know what I'm hearing.

Thanks!

 

[07Burb]

I'm curious about this too. My Burb is doing the exact same thing. My wife notices it more than I do but the times I've heard it it's always under the same conditions you just described. I believe you meant to say "5.3's" in your post, though, right?

 

[Punisher66]

loose heatshield on the cat?? I have head that before on cars with that issue and at low droning RPMS. Check it.

 

[KMeloney]

I'm curious about this too. My Burb is doing the exact same thing. My wife notices it more than I do but the times I've heard it it's always under the same conditions you just described. I believe you meant to say "5.3's" in your post, though, right?

Yep, 5.3. Whoops!

loose heatshield on the cat?? I have head that before on cars with that issue and at low droning RPMS. Check it.

Ah! That could be it. That makes sense. Thanks! I'll check it out!

 

[07Burb]

Yep, 5.3. Whoops!

easy typo to make!

Ah! That could be it. That makes sense. Thanks! I'll check it out!

I'll be checking this out this weekend as well assuming it stops raining long enough

 

[GM Customer Service]

KMeloney and 07Burb,

Please keep us posted on any information you find out regarding the noise.

Thank you,
Caron, GM Customer Service

 

[Zed 71]

Does it sound like engine knock or pinging? The way you described the condition (under load, high gear - lugging, types of sounds), may indicate knocking or pinging. What kind of gas (brand and octane) are you using and when was the last time the air filter (CAI) was checked?

Just my 2 cents.

 

[07Burb]

Does it sound like engine knock or pinging? The way you described the condition (under load, high gear - lugging, types of sounds), may indicate knocking or pinging. What kind of gas (brand and octane) are you using and when was the last time the air filter (CAI) was checked?

Just my 2 cents.

I use 87 octane and changed my air filter about 1500 miles ago. I've thought about that. If this heat shield idea doesn't turn out to be it I may try throwing in some higher octane and see what happens although that'll pain my bank account a little bit more

 

[Zed 71]

^ hopefully it is the heatshield .

 

[07Burb]

We hope. That's much cheaper (FREE) to fix than throwing in higher octane for every fill up...