BlackZLS1

iTrader: (5)

Can anyone tell me what this knocking noise is?

This video may not do justice, but theres a distinct high frequency clatter coming from somewhere in the engine. I developed this sound about a week after a heads and cam install. Initially thought it was a collapsed lifter, because its extremely loud until the oil pressure builds up at start up, but I changed all the lifters with another brand new set, and still same noise. Could it be in the bottom end, say a rod or wrist pin? Details on the engine are:

180k miles stock bottom end with Katech rod bolts installed precisely to katech specs
Trickflow 220 as cast heads
Vengeance Vindicator cam
Vengeance spec'd 7.500" pushrods for the Trickflow heads and being milled to 61cc, also verified by me during install
Comp roller trunions in stock rockers
Stock 01+ LS1 head gaskets (MLS)
LS7 lifters, both sets

I put the heads and cam in a few weeks ago. Drove and tuned on it for about a week before the knock came. During that time I did do a few high rpm runs for fun. Like I said above, I thought I had collapsed a lifter, but changed them and no change in sound. Now im thinking maybe the extra compression from the heads and 7k rpm runs did the old bottom end in for good. I dont know.

lt1pwr1

iTrader: (1)

Kinda hard to tell in the video but it sounds like a bad rod bearing to me. You said it is loud at start up but quiets down? How much does it quiet down? Can you still hear it when you rev the engine after it is warmed up?

If it were me, I would drain the oil and make sure to look for metal in it. You'll see shiny gray color in the oil if a bearing went bad. Other than that, maybe a bent pushrod? But I'm assuming you checked those when you replaced the lifters?

BlackZLS1

iTrader: (5)

When this condition first started, it would be loud at startup just until oil pressure came up, then quiet until the engine got warm, then loud again. Now its to the point of really loud at start up, and then once oil pressure comes up, not quite as loud but still really loud, and stays loud from then on. And also it gets faster and louder with rpm. Here in the video the engine is idling like at 1100 rpm so keep that in mind.

Camaroo1

cam bolts coming out maybe?

BlackZLS1

iTrader: (5)

If it was cam bolts could it be influenced by the oil pressure? Btw, I looked closely at the push rods when I pulled them, so judging by eye they aren't bent.

WS.SIX

iTrader: (3)

Pull out your trusty mechanics stethoscope and start prodding around until you can narrow down the area the sound is coming from before you rip anything apart.

BlackZLS1

iTrader: (5)

I got the stethoscope out, sounds like its coming from the front of the engine. Possibly the oil pump itself? I got alot of sound off the water pump, timing cover, and front of the oil pan area. Gonna pull it apart tomorrow and check that out. Its a new melling high volume. Hopefully reveal something.

WS.SIX

iTrader: (3)

How'd it go?

BlackZLS1

iTrader: (5)

I got it all tore down to the oil pump and was in the process of removing the oil pump when I realized that my oil pump pickup girdle that I installed was going to make it next to impossible to remove the pickup tube without removing the oil pan. So my next move was to drain the pan, and I seen the silverish oil on the drain plug and a very excessive amount of metal on the magnet of the plug. And this is on an oil change with maybe 5 miles of driving and about 30 minutes of total run time. And the metal wasn't exactly fine. So I'm back to thinking its bottom end related.

WS.SIX

iTrader: (3)

Ouch...

Since you are already pulling the pan pop off the front 1 and 2 rod bearing caps and see how they look. I don't want to restart the whole argument about katech bolts not making the rod caps out of round but if this is the case it's time to shortblock it!

Endrance

Metal shavings and silvery oil = spun bearing. Sucks man time to buy an LS3! Lol