IAGXP

iTrader: (1)

That's what I was most afraid of. There was a banked curve that's basically a large bowl you drive around, (this part of the track must've been used for go kart racing at one point). I went around it at the top of first gear running some pretty high rpms.

06 SS

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.

IAGXP

iTrader: (1)

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.

AlabamaGuy

iTrader: (5)

First off, I vote for doing trans while the motor's out.
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.

SidewaysV8

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

AlabamaGuy

iTrader: (5)

The fact that it includes non-LS4 cars leads me to believe this is a V6 issue.

SidewaysV8

I would agree, as most of the other Engine Related TSB's specifically refer to L67, L26, L32, etc.

IAGXP

iTrader: (1)

I'm having a used engine with 3,000 miles put in and having the trans rebuilt. Guess I need to look for another car to autox since I can't break my daily driver again.

jderou_GXP

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.

LS1 Racing

iTrader: (15)

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.

IAGXP

iTrader: (1)

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.

LS1 Racing

iTrader: (15)

I'm pretty sure an LS7 dry sump will work. But then there's the issue of $$.

SidewaysV8

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.

LS1 Racing

iTrader: (15)

Geez. No wonder AMC went under. Makes me wonder if they used the oversized bearing because they put a turned crank in it, too!

jderou_GXP

Yeah well my '98 chevy K1500 has a bottom end knock when its cold. There is a tech service bulletin on it, they call it "improperly sized main bearings".
They aren't fixing it, but their just letting me know "our bad" lol.

SidewaysV8

Actually, it was quite common to stock 3 oversizes of bearings. Why throw away a perfectly good crank because someone ground the journals undersize? The problem was that the supplier of bearings either mixed up in one of their shipments to the Kenosha plant, or the assembler grabbed one of the oversize bearings instead of 6 nominal sized bearings when he assembled the engine. And I've got news for you, DCX did more to damage Jeep than AMC ever did. That AMC built 4.0 ran stronger than any of the other DCX built 4.0's that I've owned and I've owned (and still own) alot of Jeeps.

IAGXP

iTrader: (1)

Is there any sort of a break in period for a rebuilt trans? Do I need to take it easy or just drive it like I'm going to drive it from day 1?

DavidGXP

iTrader: (14)

How well does your car do when you auto cross? Do you loke it?

IAGXP

iTrader: (1)

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???

IAGXP

iTrader: (1)

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.