FourG63 97GST

you talking about the copper on the bearing? or what looks like a crack? How does the cam look?
showing copper is surprisingly normal for the cam bearing. take an LS engine apart from the showroom floor and it'll show copper too. mine showed copper at 30k when I did 1st cam swap, and still showed copper at 110k doing the 4th cam swap.
Car sounds like a standard pushrod LS to me

apexslider

after reading a bunch on here the copper didn't worry me too much. I was actually going to start ordering some parts to start putting it back together. I decided to have my buddy stop by with his bore scope real quick and yes, we found the busted bearing.
The cam didn't look bad when I pulled it. Its down at the machine shop right now, I'll grab some pics when I go pick it up in the next couple of days.

when you hear it in person, it definitely doesn't sound like a standard LS. My LS3 sounded nothing like this one. And I've recently been listening more closely to LS's driving, and I don't hear any of them rattling like this thing did.

ptindall

Any idea what caused the cam bearing to crack or how a cracked cam bearing would result in a loud noise? I just hope there isn't something else going on you're missing.

apexslider

That's my million dollar question. I've talked to few LS builders and they say they've never seen a cam bearing do that. But the bearing looks pretty shot, a lot less material where it cracked then the rest of the bearing. The pic doesn't do it justice, but I'll get more when the motor comes apart and the bearings come out.

I did notice the harmonic balance had some wobble to it, and when I pulled it off I could see the rubber had some cracks and wear to it. I'm new to diving into LS's so I'm not sure if that could cause cam bearing issues or not. If it can, then I expect to see a high level of bearing wear in the bottom end as well.

But I'll have the short block out of the car this weekend and down to the machine shop next week. I'll know more after they inspect everything.

apexslider

small update...

The machine shop tore the motor down and discovered the engine had been apart before and has two different sets of rods in it. One bank had one set of rods and the other bank had a different set. There was a 10-12 gram difference between each differing rod. The shop said they all appear to be OEM and were likely replaced due to noise; likely piston slap. A number of the piston/cylinder clearances were out of spec; majority were around .003, max spec being .00212.
They also said one bank of rods bearings pretty much fell out when they started removing the rods. And, there is some wear on the rods big end.
I picked up the parts that came out, so I'll try to post some pics. Really, they don't look terrible, but I'm not using two different sets of rods going forward...and the a number of the pistons did rock in the cylinder when I pulled the heads...so full rebuild is under way.

ptindall

Sorry to hear you got such a cobbled engine with only 23,000 miles. That's just not fair. Thanks for the update.