Wierd issue with a 5.3 chevy

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BadAss71

BadAss71

Let's Go Brandon
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Here's a weird one for ya. So we had a customer bring in their 03 Chevy avalanche complaining of a strange noise from the engine and rough running with a cel on. Pulled the codes and found 3 all related to the drive by wire system. Ran a bunch of tests and basically pinpointing the actual throttle body as the culprit. Well here is where it gets interesting, the noise the customer was complaining about really sounded like a lifter tic, which these engines are kinda known for. Oil level was good, they had just taken it to get done a week before and it looked fine. As we were running some tests with the engine hardly able to keep an idle the noise started getting louder and louder and ultimately started knocking really loudly, like a rod just let go. Ran a compression test and found one hole completely dead. We decided that the engine needed to come out and be torn down to find the issue. So to remove the engine the intake manifold needs to be removed for clearance. Intake comes off and we notice this gold flakey pieces all over inside it and the intake runners in the heads. Its hard to explain what it is really but it looks like kids glitter they use for projects or what not. Most of the pieces are about a sixteenth of an inch in size and are very shiny. Its definitely a metal substance for sure. We then proceeded to get the engine out and torn down. All of the rod and main bearings look fine, no issues at all. The piston rings and skirts look great, just the tops of the pistons have that same material on them. Then noticed one of the exhaust valve springs was broken, it split right in the middle? I haven't seen that with these engines at all. We can't seem to be able to pinpoint where this gold material came from. We inspected the brake booster and vaccum line as well as the emissions purge line but found nothing. If you look into the intake where the throttle body would be mounted you see where it looks like someone removed the pcv line at the valve and let the engine suck this crap inside of it. I'm leaning towards a sabotage type issue. What are your guy's opinions? I just can't really see any other possibility.
 
You wouldn't get the bronze from the guide in the intake. Check the throttle body. See if it's coming off the blade area or possible check the
mass air flow sensor. They could also cause the rough running.
Good luck, sounds like you'll need it.
 
johnparts said:
bronze from the exhaust guide?
Click to expand...
We were thinking something along those lines also, but for the amount of material and where it ended up it just doesn't make sense.
briankaplan said:
You wouldn't get the bronze from the guide in the intake. Check the throttle body. See if it's coming off the blade area or possible check the
mass air flow sensor. They could also cause the rough running.
Good luck, sounds like you'll need it.
Click to expand...
The throttle body looks great, no issues there. I know the broken valve spring on the exhaust side is definatly causing most of the rough running but we can't figure out what the loud knocking noise was. It's really strange. We just want to make sure the new engine we install doesn't end up like this one. I really feel something devious happened. I will post a picture of the material we found.
 
Here's a pic of one of the intake ports. That same material is in every single port but more so in the center four.
 
Here's a thought, although possibly a stupid one, maybe someone dropped something in by mistake when working on it and the engine chewed it up. I've seen people leave stuff in and around engines before.
 
Granted, sabotage is hardly ever done with a clear frame of mind, but it seems kind of hard to believe that somebody would sabotage the motor with a material that would be so distinctive and recognizable upon engine tear-down.
The only thing I didn't see you mention was the condition of the cam bearings. Is it possible that those got totally smoked, and the flakes bled down into the crankcase and were then sucked up by the PCV?
 
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