I have a 2003 Sierra with a 4.8l and a problem. It has 123505 miles on it. Yesterday morning I went to start my truck for work and it responded with a horrible knocking sound and no oil pressure. I Immediately shut it off. After work I went to look at it a little further and started it again. This time I was able to narrow the knocking noise down to the drivers side bank. All the plugs from that bank are covered in oil, even to about halfway up the threads. All of this happened very suddenly. It ran perfectly fine the day before yesterday, took a crap on me yesterday. HELP!?!?

 

Then my friend you just have a knock in the engine , where it comes to the spark plugs with oil that's normal , they get covered pretty good from the valve covers , but other then that could be a knock or your lifter..

 

My worry is that the knock is VERY loud. I forgot to mention that I have DTC codes saying that I have multiple cylinders misfiring, and knock sensor 1 low input

 

Other guess for me that you probly have a broke piece of carbon in your cylinders

 

Possible o-ring failure on the pick up and oil pump connection?

 

If you have no oil pressure and a knock you most likely need a new engine. Did you check to see if the oil level was correct? It is possible that the engine burns oil and there is no oil left.

 

this is from the #6 cylinder... I'm guessing rod bearing?

 

and the engine does burn oil, around 1qt per tank or 2, but i keep on top of it and it was 1qt before the fill line on the dipstick.

 

That looks like pieces of melted Aluminum?

Here is what I just went through with an oil pressure problem on a 4.8...

https://chevroletforum.com/forum/exp...r-noise-55524/

 

Well I found the source of my issue. This is the picture of my #6 Cylinder. This is exactly how it looked when I pulled the head from it. completely "ate" the piston.