So not sure where to start. I've searched a couple hundred threads within the last month really hoping someone had the same issue... no luck so far or possibly just not wording it correctly.

So to start off ive researched how the displacement engine works and the engineering behind is pretty ingenius. Ive heard from a couple other chevy owners that have the 5.3 and pontiac owners with the grand prix say they have heard the same issue but nothing damaging has happened.... yet.

When the engine decides to engage into 4cyl mode the engine makes a weird swirling bearing noise... kinda like someone taking a bearing ball in a cup and swirling it around... took it to the dealership and they said no codes are being thrown and they cant hear the issue during test drive... I can hear it clear as day driving near curbs at speeds of around 25 to 40mph. The other issue while in 4cyl mode is almost like an engine braking. Going from 40mph down to a stop the car tends to shudder until swapping back to 8cyl mode then its smooth.They said it might be the piston slap which is normal for these motors going into 4cyl mode due to the 4 cyl that are not being used...
Another issue was the cracking cylinder heads. Not sure what the hell that sounds like but its nothing I want to be near if it is the issue.
During 8cyl mode the engine sounds smooth and beautiful. No swirling noise, no shuddering nothing... its perfect.
Btw ive changed my rotors and brake pads religiously so I know its not a warped rotor.
The pontiac owner I talked to said he tuned out the 4cyl mode and has never had an issue hearing it or feeling it since. Now this could be a solution, but still doesnt put my mind at ease until I can figure it out.
Any help, suggestions, or tricks would be appreciated.

 

This explanation is a long shot and im not sure if this is completely factual but ive HEARD that when the car switches from 8 to 4, the timing chain tends to "loosen" due to less tension from 4 less cylinders turning your crank, this might cause that rhythmic bearing sound you described....many people get around this by just driving around in gear 3 instead of D so the DOD never activates

 

Haha too funny. That is exactly what I do. So maybe this may be the problem. How easy or diffucult is it to tighten the timing chain, or would it need to be replaced?
Either way tho, will this cause any severe issues with the engine if not changed?

 

IF thats the problem, chain replacement might help, or it might not, might just be an individual flaw specific to a limited number of 5.3's, im not sure on the 5.3 but most vehicles have an automatic chain tensioner that might be the culprit....i would say that as long as the chain doesnt break or skip time, then its a non issue...however if the chain isnt the problem and its something else like piston slap on DOD activation, then its a bit more serious of a problembecause its gonna do a bit of damage to our piston wall....idk im reaching the end of my usefulness here in what i can think of, hopefully a member with the LS4 will comment

 

Yep tuning out your Dod should resolve your issue, it's kinda useless anyway. Main cause of oil consumption in these ls motors.

 

My problem with the DoD was every time it switched back and forth, the torque converter would come unlocked, rev's would bounce around, then it would lock again. It was all very uncomfortable. Maybe that's what you hear? Or it could be the solenoid that turns on the DoD you hear?
So, I had it tuned out, after I got the tranny rebuilt.
I'm thinking motor re-build next spring, with no dod (new heads?)

Anyway, the tune made it run better. Will at OverKill did mine, but it was custom since I live close. He just took the car for a drive.