Engine knock
rod bearing. probably got starved during cornering at your event. does it do fine when the metal is cool and slightly less expanded and start becoming more audible after the it warms slightly, increases rythmically at higher RPM? I would bet you are looking at a bottom end rebuild.
TECH Fanatic
Joined: Jan 2007
Posts: 1,029
Likes: 0
From: LITH, IL.
I hope not, but as your piston speed increases, for lack of a better phrase, it hits harder after it takes up the the slack from the melted/missing bearing. I had personal experience on a rather nice 400 small-block when I was a kid. Did exactly the same thing.
The shop called, they think it's a bearing in the bottom end. The question now is rebuild, or put in a used motor. I'm leaning towards used motor. They found two, one with 3k miles, the other with 6k but had to run the numbers first. Is it possible this has been going out for a while and just started knocking? If one sustained high rpm curve could do it I better not play around on any interstate on or off ramps anymore. I'd like to say I'm moving on and getting something new, but I'll have WAY too much money into this car to ever get rid of it. Next thing will be the god damn tranny and then I'll have to drive this until I die.
The shop called, they think it's a bearing in the bottom end. The question now is rebuild, or put in a used motor. I'm leaning towards used motor. They found two, one with 3k miles, the other with 6k but had to run the numbers first. Is it possible this has been going out for a while and just started knocking? If one sustained high rpm curve could do it I better not play around on any interstate on or off ramps anymore. I'd like to say I'm moving on and getting something new, but I'll have WAY too much money into this car to ever get rid of it. Next thing will be the god damn tranny and then I'll have to drive this until I die.
Second, it seems strange for the bottom end on a N/A LSx to be going already. Get them to show you the bad bearing when they take it out.
On The Tree
Joined: Nov 2009
Posts: 129
Likes: 0
From: St. Louis, MO
This is the only TSB I've ever seen regarding a bearing issue but it's for 2008 models only from the NHTSA website.
Make / Models : Model/Build Years:
BUICK / ALLURE 2008
BUICK / LACROSSE 2008
BUICK / LUCERNE 2008
PONTIAC / GRAND PRIX 2008
Service Bulletin Number : 07294
NHTSA Item Number : 10023955
Summary Description :
SERVICE UPDATE FOR INVENTORY VEHICLES ONLY - #4 MAIN BEARING OIL FEED PASSAGE NOT DRILLED - EXPIRES APRIL 30, 2008. *NJ
Make / Models : Model/Build Years:
BUICK / ALLURE 2008
BUICK / LACROSSE 2008
BUICK / LUCERNE 2008
PONTIAC / GRAND PRIX 2008
Service Bulletin Number : 07294
NHTSA Item Number : 10023955
Summary Description :
SERVICE UPDATE FOR INVENTORY VEHICLES ONLY - #4 MAIN BEARING OIL FEED PASSAGE NOT DRILLED - EXPIRES APRIL 30, 2008. *NJ
This is the only TSB I've ever seen regarding a bearing issue but it's for 2008 models only from the NHTSA website.
Make / Models : Model/Build Years:
BUICK / ALLURE 2008
BUICK / LACROSSE 2008
BUICK / LUCERNE 2008
PONTIAC / GRAND PRIX 2008
Service Bulletin Number : 07294
NHTSA Item Number : 10023955
Summary Description :
SERVICE UPDATE FOR INVENTORY VEHICLES ONLY - #4 MAIN BEARING OIL FEED PASSAGE NOT DRILLED - EXPIRES APRIL 30, 2008. *NJ
Make / Models : Model/Build Years:
BUICK / ALLURE 2008
BUICK / LACROSSE 2008
BUICK / LUCERNE 2008
PONTIAC / GRAND PRIX 2008
Service Bulletin Number : 07294
NHTSA Item Number : 10023955
Summary Description :
SERVICE UPDATE FOR INVENTORY VEHICLES ONLY - #4 MAIN BEARING OIL FEED PASSAGE NOT DRILLED - EXPIRES APRIL 30, 2008. *NJ
The fact that it includes non-LS4 cars leads me to believe this is a V6 issue.
On The Tree
Joined: Nov 2009
Posts: 129
Likes: 0
From: St. Louis, MO
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On The Tree
Joined: Apr 2010
Posts: 108
Likes: 0
From: Missouri
Think maybe the high flow oil pump of the LS4 pumped the sump too low and starved the bearing?
Bound to be a mod to prevent this, hate to see someone have to go easy on their car to avoid something like this.
Bound to be a mod to prevent this, hate to see someone have to go easy on their car to avoid something like this.
LSx bottom-end failures are pretty rare. I'll bet you can Auto-X with the new motor and trans and not worry abou it, though I would see how much you can overfill the crankcase, just in case there isn't enough baffling in the pan to keep oil around the pick-up.
I'm getting the old motor back and plan on pulling the pan to take a look at the baffels (if there are any) and see how low the pickup goes. Unless someone else here can enlighten me. One option would be an accusump setup but that seems extreme. If things aren't too bad I'll either part the motor out or have the bottom end rebuilt and strap it into the back of a Fiero.
I'm getting the old motor back and plan on pulling the pan to take a look at the baffels (if there are any) and see how low the pickup goes. Unless someone else here can enlighten me. One option would be an accusump setup but that seems extreme. If things aren't too bad I'll either part the motor out or have the bottom end rebuilt and strap it into the back of a Fiero.
On The Tree
Joined: Nov 2009
Posts: 129
Likes: 0
From: St. Louis, MO
The 5.3L LS4, however, was designed to mount transversely (sideways), compared to the longitudinal installation of the 6.0L LS2 and every small block V8 before it. Its crankshaft is shortened 13 mm – 3 mm at the flywheel end and 10 mm at the accessory drive end – to reduce the length of the engine compared to the 6.0L. All accessories are driven by a single serpentine belt to save space. The water pump is mounted remotely with an elongated pump manifold that connects it to the coolant passages. Revised oil pan baffles, or windage trays, are incorporated into the LS4 to ensure that the oil sump stays loaded during high-g cornering. With its front-drive layout, the LS4’s exhaust manifolds are joined by a crossover pipe, with a single, high capacity underbody catalytic converter
I had an 87' Cherokee with the 4.0 liter I6 that developed a bottom-end knock at about 20k miles, along with low oil pressure. The service manager showed me the rod bearing that they replaced and apparently when the engine was built, they used an oversized bearing on that journal. It's possible something like this happened with yours.
So much for that huh?
I had an 87' Cherokee with the 4.0 liter I6 that developed a bottom-end knock at about 20k miles, along with low oil pressure. The service manager showed me the rod bearing that they replaced and apparently when the engine was built, they used an oversized bearing on that journal. It's possible something like this happened with yours.
I had an 87' Cherokee with the 4.0 liter I6 that developed a bottom-end knock at about 20k miles, along with low oil pressure. The service manager showed me the rod bearing that they replaced and apparently when the engine was built, they used an oversized bearing on that journal. It's possible something like this happened with yours.
On The Tree
Joined: Apr 2010
Posts: 108
Likes: 0
From: Missouri
They aren't fixing it, but their just letting me know "our bad" lol.
On The Tree
Joined: Nov 2009
Posts: 129
Likes: 0
From: St. Louis, MO
It was pretty fun, the car did ok. STB's and the right tires made a huge difference. The best part was people coming up after a run to look under the hood with a puzzled look on their faces, this thing has a V8???
I got the car back on Thursday. The dealership found a used motor with 19k miles for 1400.00. In addition to that I had the trans rebuilt, new tie rod ends on both sides, and a new battery installed. So far it's running awesome and seems to pull harder in every gear. I didn't realize how bad the old trans was until driving it with this rebuilt one. The tech said there was a bunch of metal shavings in the oil when they drained it and they think it was a rod bearing but never dropped the pan to investigate since it was obvious the motor was done. I got the old motor back and plan on dropping the pan and taking a look. My next question is what should I do with the old motor, part it out, sell it to the junk yard, or keep it for parts? I plan on keeping this car for a LONG time now.