Seriously bad sounds from engine

[Sgtduckyboy]

I replaced my cam and other parts in december. The thing has been running great. a few weeks ago, i heard what sounded like exhaust leak under a heavy load, like accelerating. I figured I'd get to it when it warmed up and I had some time on a weekend. This weekend it got worse. It idles quiet, on acceleration without load, sounds good, but starting to hear some 'deep rattle' noise, best I can describe it. Its not the valve/lifter rattle noise, this is deeper in the engine, sounds more like its coming from under the car. Then when I drive it, it really sounds bad under load. I know I need an oil change, but dont expect this to fix it and going to do that first, just to see if it quiets it down some. I also got 'low oil pressure' light on while driving even though the guage said 10psi or more. I parked it and just riding the bike right now. My hunch is the journal bearings or rod bearings may be affected. I did have some metal get into the engine last winter when the valve lifter stuck in the bore and we replaced the lifters/cam/springs on the upper end and put on a new oil pump/water pump/timing chain in the process. I had a feeling I should have sold it then! ugh. anyway, if anyone has a clue what I might be experiencing and what to look for, I'd appreciate some pointers. Thanks. 2006, Tahoe 5.3 Z71, no Fuel mgmt. I did have Lewis and diablo help me get some tunes on it and I did drop the last WOT tune on it this weekend, I feel the WOT is what caused this as I havent done any WOT running on it but in the last month, I've done a few and it seems to have gotten worse since I did this. Not sure if that helps but figured I should mention it.
thanks!

 

[Sgtduckyboy]

I replaced my cam and other parts in december. The thing has been running great. a few weeks ago, i heard what sounded like exhaust leak under a heavy load, like accelerating. I figured I'd get to it when it warmed up and I had some time on a weekend. This weekend it got worse. It idles quiet, on acceleration without load, sounds good, but starting to hear some 'deep rattle' noise, best I can describe it. Its not the valve/lifter rattle noise, this is deeper in the engine, sounds more like its coming from under the car. Then when I drive it, it really sounds bad under load. I know I need an oil change, but dont expect this to fix it and going to do that first, just to see if it quiets it down some. I also got 'low oil pressure' light on while driving even though the guage said 10psi or more. I parked it and just riding the bike right now. My hunch is the journal bearings or rod bearings may be affected. I did have some metal get into the engine last winter when the valve lifter stuck in the bore and we replaced the lifters/cam/springs on the upper end and put on a new oil pump/water pump/timing chain in the process. I had a feeling I should have sold it then! ugh. anyway, if anyone has a clue what I might be experiencing and what to look for, I'd appreciate some pointers. Thanks. 2006, Tahoe 5.3 Z71, no Fuel mgmt. I did have Lewis and diablo help me get some tunes on it and I did drop the last WOT tune on it this weekend, I feel the WOT is what caused this as I havent done any WOT running on it but in the last month, I've done a few and it seems to have gotten worse since I did this. Not sure if that helps but figured I should mention it.
thanks!

I wanted to add, i do have a bad O2 sensor, heater part of it. Trims are good, based on what we have been doing with Lewis. i am going to check the cats though. i wonder if i am getting some back pressure on that side.

 

[swathdiver]

Which O2 sensor, upstream or downstream? Did you check the torque converter bolts? I hope its something like that and not the bottom end.

 

[Musicars]

The last time I had a "deep rattle" it ended up being a cracked flex plate. This would be related to swathdiver's question about torque converter bolts. Wouldn't tie in with low oil pressure but occasionally I have had multiple issues at the same time. Just a thought.

 

[Sgtduckyboy]

UPDATE: looks like CATs are fine, nice and hot on the downstream side. voltage pretty steady too. the upstream bank 1 is the one that is reporting that it isnt heating up, so wont be accurate when its cold, is what i can find out. anywho, my neighbor who is an old SBC guy, heard it and shook his head, he would bet its crankshaft or rod with an issue. but just to be sure, here is a video, see if any of you hear something. it got a lot better after i changed the oil tonight, but that is just lipstick on a pig, I know.
https://drive.google.com/file/d/17XKSJTUdpJ6TqQ96TK0EJ7QyeFpUB5Sjuw/view?usp=sharing

 

[Sgtduckyboy]

UPDATE: looks like CATs are fine, nice and hot on the downstream side. voltage pretty steady too. the upstream bank 1 is the one that is reporting that it isnt heating up, so wont be accurate when its cold, is what i can find out. anywho, my neighbor who is an old SBC guy, heard it and shook his head, he would bet its crankshaft or rod with an issue. but just to be sure, here is a video, see if any of you hear something. it got a lot better after i changed the oil tonight, but that is just lipstick on a pig, I know.
https://drive.google.com/file/d/17XKSJTUdpJ6TqQ96TK0EJ7QyeFpUB5Sjuw/view?usp=sharing

its official, starting to throw a rod probably. bearing is out on one of the pistons on the bottom.

next question, i can get a great deal on an 09 avalanche or 08 suburban, both are in great shape, just over 100,000 miles. 5.3 with DOD/AFM which I would delete.
thoughts???

 

[M1Gunner]

Sounds like a great time to just upgrade the engine!

 

[Sgtduckyboy]

Sounds like a great time to just upgrade the engine!

I wish I had the desire/time/energy right now. I might work the deal so I can keep it, and fix it later. Love my 'Hoe!

 

[swathdiver]

The '09 will have the 6-speed transmission and maybe Bluetooth. Which would you find more useful and which is optioned best to your liking?

 

[Sgtduckyboy]

I wish I had the desire/time/energy right now. I might work the deal so I can keep it, and fix it later. Love my 'Hoe!

Well, things have changed.. found a used 02 Tahoe from a friend for $2K. CAn then use it until I do Pull mine, repair it, replace it, verify it works, then sell this older one.
guess I'll be doing the big project!
need a lift plate
need a lift
need an engine stand.

those lift plates are as much as the engine stand!! and i should only need the bearings for the connecting rods, main seals, oil pan gasket for the most part. maybe one new connecting rod if i wore into it and/or a new crank. all the time to remove/replace the engine, only costs a few hundred in parts... just sad. but i'm sure i'll do some upgrades while I am in there.. maybe headers? if i need to replace all piston rings, maybe some new flat top pistons?? hmmmmm the possiblities excite me!