charcold-bowtie

iTrader: (10)

After my tranny trouble, these threads make me sick. I hope my little 4.8 never dies lol.

Wheatley

iTrader: (12)

Had that happen before,spum cam and rod bearings

Tootall

iTrader: (79)

did you put the oil block off in the rear of the engine . . . little orange plug for the lifters

l_kusler

Yea, i'd say i'm with Joe.. knocking is not from a couple pounds oil pressure loss, you still got 20, that should be lots.. a mechanical failure is giving you oil pressure loss. Sounds like it might have to come out... sorry to hear

hirdlej

iTrader: (31)

I'd get a mechanics stethescope or a chunk of wooden broom handle and start listening to where the noise is coming from. Is the noise at the same speed that the crankshaft is rotating? Is it at half speed (valvetrain related)? Don't drive it whatever you do but let it run a short bit and listen around. If it sounds deep or pronounced near the bottom of the block or pan area take the engine out now while it can be fixed cheaply. Better than having a LS2 block with a hole in the side. Chances are everything is fine except the crank, maybe a rod and the bearings trashed. You may get out of it cheap if you can pinpoint the sound and not let anything else get worse.

phasemaster1

iTrader: (11)

I had a loud nasty knock when I did my cam and oil pump like at 50,000 miles. Drove it for a few days everything was fine then it started making the knock noise the oil pressure was a little down but just under 40 psi at idle. It ended up being I had installed the wrong oil pump o-ring guess pressure dropped enough that a lifter was not pumping up. That lifter was loud enough people thought a rod or a bearing went . Changed the o-ring and now Im at 98,000 miles no noise. Good luck.

Jaime

THE-HOE

iTrader: (3)

Thanks for the info. I had a broken off broom stick and listened around, it is almost quiet at idle, but gets loud when slightly revved up. But while i was trying to pinpoint the problem i noticed the oil pressure dropping down near 10lbs, and the knock getting worse, i just immediately shut it off. Im going to have to take the thing back out i believe. I think im going to start another thread here about if i should go with the ls2 402 stroker kit or not.

2001si3rr@

iTrader: (1)

My wifes 2004 Tahoe started doing this, almost sounds like what your experiencing. On cold starts it will knock, mainly from the bottom end near the front of the motor, but if I let it alone and warm up it will go away and sound fine. maybe running for a minute for the knock to go away. I noticed the oil pressure was really low, down to the first big line not numbered, guessing 20 psi. We took it to the dealership and they pulled the oil filter to put on the adapter to check mechanical oil pressure. It checked good at 40 psi. I'm like no, it's been very low at around 20 psi. He puts on a new filter and it fine. Then 2 days later same thing, knocking, low oil pressure. So I pick up a new filter and 6 quarts of oil, change the oil and put in the new filter. Again it's fine.

I change the oil regularly with Mobil 1 and always use a Delco filter, when this happened it was down to 70% on the GMOLS.

So, I decide I'm gonna cut the filter open. I used a hack saw to cut the crimp off the end of the filter and pull out the element. Thinking I'm gonna find metal shavings and such.... To my surprise I found thick slime, I'm guessing sludge? But, like I said I always run Mobil 1, no way this stuff sludges up. I thought anyway.

If I were you I'd change the oil and filter, cut open the filter like I did and check for metal.

That's as far as I've gotten with mine for now, I'm gonna change it again when it gets down to 50% and open up the filter and take another peek to see. Hopefully I can work this crap out.

Also mark your coolant bottle when the truck is completely cooled down, I've heard a small head gasket leak could allow the DexCool to get into the oil system, and gel up like this. If you are loosing any coolant and show no signs of an external leak, that could be the problem. Basically the filter catches it and clogs up quick containing what it can.

Hope this helps you some.

white lightning SS

iTrader: (3)

Trailblazer SS guys have been having oil pressure and engine failure problems. I dont think they know the cause. Seems to only effect aluminum LS2's. Sorry to hear the news. Might be worth checking to make sure the oil pick-up oring is O.K. but the knock indicates damage.

dc303

My motto is "breakin parts are an opportunity to buy bigger and better stuff"

Tear it down stroke it(the crank) and smile when you go WOT!!!