Guys I need help figuring out this engine rattle

[iamdub]

@iamdub I agree, doesn't sound like anything I've seen online but the sound is coming from the top end. I plan on pulling the heads off this weekend to find the answer here but I want to get the parts ordered as soon as possible. If I find the damage it outside my scope of ability to repair and I have to return the parts, so be it.

p0306 cylinder 6 misfire is the only code

Hmmm. #6 is an AFM cylinder, but on the RH bank (passenger side). Looking forward to updates.

 

[swathdiver]

@swathdiver Thank you for that, I am going to look into getting that cam. Can you take a look at this parts list from Texas Speed to make sure I have everything selected correctly? This will be a for a 08 5.3.
View attachment 372865

I didn't see a part number for those lifter trays. Make sure they are GM OE and settle for nothing else unless tie bars. Everything else looks good. Which lifters are best?

 

[Geotrash]

@iamdub I agree, doesn't sound like anything I've seen online but the sound is coming from the top end. I plan on pulling the heads off this weekend to find the answer here but I want to get the parts ordered as soon as possible. If I find the damage it outside my scope of ability to repair and I have to return the parts, so be it.

p0306 cylinder 6 misfire is the only code

Lifter sounds often transmit through the pushrods and can sound like they're coming from the top end.

What's different about yours though is that the frequency is faster than camshaft rotation and seems to match crankshaft rotation speed. Let us know what you find when you pull the heads. Also, I would consider getting the ARP head bolts (bolts, not studs). They're reusable and can be torqued directly to full value, instead of torque-to-yield. They also make exhaust manifold bolts, which is what I used also.

 

[George B]

What's different about yours though is that the frequency is faster than camshaft rotation and seems to match crankshaft rotation speed.

I agree with this and am beginning to wonder if a piston skirt may be broken.

 

[FasterBass]

I agree with this and am beginning to wonder if a piston skirt may be broken.

Hence my rod knock comment. Way too fast for the cam.

 

[George B]

Hence my rod knock comment. Way too fast for the cam.

And its a sort if a dead knock not a tick. Like a piston hitting the head.

 

[Dustin Jackson]

I appreciate everybody's input. This is pretty stressful for sure. This weekend I am going to try to get the heads off and taking everybody's thoughts into consideration while I am digging for answers.

Today I am going to disable my fuel pump and turn the engine with the starter to see if I can replicate the sound. From there I will take the heads off this weekend and do the same thing. If I can produce the sound while turning the engine with the heads removed then well... that would be outside of my ability to repair it because the problem is in the bottom end somewhere and probably looking to get a new engine.

I am hoping that pulling the heads I will find some problems with the lifters, push rods, or valvetrain. I will also inspect the cylinder walls for damage like some have suggested the piston being the source of noise.

I appreciate everyone's support in this, if you have any other useful advice that would be great. This was a great running Tahoe until the day this happened, crazy how things go sometimes.

 

[George B]

I appreciate everybody's input. This is pretty stressful for sure. This weekend I am going to try to get the heads off and taking everybody's thoughts into consideration while I am digging for answers.

Today I am going to disable my fuel pump and turn the engine with the starter to see if I can replicate the sound. From there I will take the heads off this weekend and do the same thing. If I can produce the sound while turning the engine with the heads removed then well... that would be outside of my ability to repair it because the problem is in the bottom end somewhere and probably looking to get a new engine.

I am hoping that pulling the heads I will find some problems with the lifters, push rods, or valvetrain. I will also inspect the cylinder walls for damage like some have suggested the piston being the source of noise.

I appreciate everyone's support in this, if you have any other useful advice that would be great. This was a great running Tahoe until the day this happened, crazy how things go sometimes.

Good luck and keep us posted.

 

[Dustin Jackson]

Here is another video I took this morning, focusing on the passenger side. The sound definitely is stronger coming from passenger side.

Here it is after I gave it a couple revs. I guess it's hard to tell where the sound is coming from top or bottom.

 

[Geotrash]

Here is another video I took this morning, focusing on the passenger side. The sound definitely is stronger coming from passenger side.

Here it is after I gave it a couple revs. I guess it's hard to tell where the sound is coming from top or bottom.

2nd video makes it sound much more like valvetrain noise. Good luck getting the heads off and finding your smoking gun. We'll be here when you need us. :-D