Engine rattle with video

[Backwoods16]

Any ideas what this is? 5.3 V8. 135k miles. Its hard to hear while driving but increases with higher rmps. I changed the serpentine.belt, idler pulley and tensioner over the weekend.

[video=youtube;dja_KHhfLUM]https://www.youtube.com/watch?v=dja_KHhfLUM&feature=youtube_gdata_player[/video]

Oil level was a quart low, changed regularly with mobil 1. Truck runs normal, no loss of mpg and no leaks from what I can tell. Accleration is normal as well is idle. Not throwing any codes either.

 

[CaptainXL]

I don't hear any rattling but I do hear what sounds like an exhaust leak.

 

[Backwoods16]

Where should I begin my search? Manifold? Shouldn't this throw a code? Ill check for pending codes.

 

[BRomanJr]

Where should I begin my search? Manifold? Shouldn't this throw a code? Ill check for pending codes.

Please fill out the rest of your Profile, 03 and 04 5.3's were pre-DOD, 05 and above had DOD which adds a lot of parts that can make noise.

I agree that your sound is more like an exhaust leak.

On my 04 it had multiple busted exhaust manifold bolts (mostly near front and back) I also had a bad donut gasket between the driver side exhaust manifold and the pipe.
I thought the broken bolts were causing the noise, but after I found the bad donut, that was more likely my noise. By the way I ended up replacing all of the exhaust manifold bolts on both sides and getting broken ones out was not fun.

 

[Backwoods16]

Thanks, ill start looking at the manifold and work my way back from there. Profile is updated. This makes sense now as I was smellong.gas in the truck the other day. Ill be keeping the windows open.

 

[DenaliHD66]

I have gotten the exaggerated "engine diesel sound" with my 4.2L lately. Thinking the exhaust manifold is gonna need replaced.

 

[CaptainXL]

I have gotten the exaggerated "engine diesel sound" with my 4.2L lately. Thinking the exhaust manifold is gonna need replaced.

I would check before condemning the manifold. I thought my manifold was cracked as well but it ended up being just the gasket.

Btw, if anyone is interested I have a manifold to sell in good condition.

 

[DenaliHD66]

I was goin to replace it anyway. The 04's I've read don't have the best luck with manifolds, but also my o2 sensor is rusted in there so I can't replace it.

 

[CaptainXL]

but also my o2 sensor is rusted in there so I can't replace it.

Been there. It will come out with a pipe wrench.

 

[Backwoods16]

Still havent tracked down the source of my exhaust leak, the sound is the loudest at the top of the intake. Manifolds appear to be ok, at least I cant see or hear a leak using a tube. Could the noise in the video be related to a leak further down the exhaust system? I also checked all hoses, they appear good. Manifold bolts arent loose, possible gasket?

 

[DenaliHD66]

If there was a leak anywhere in the exhaust, specifically the manifold, would that affect a compression test or not? I'm thinking it wouldn't...