2003 Tahoe, Accidental Project

So a couple of weeks ago I posted about my 200k mile 2003 Tahoe that died when exiting the freeway and then picked up a knock.  The first place I took it said to put a new engine in it, even though the bottom end bearings were fine, there was no metal in the oil, and everything in the valvetrain was fine.  They had no idea what had gone wrong, but guessed that a new engine would fix it.  I declined, rented a trailer and pulled it 200 miles home.

I took it to a place locally which is run by a friend.  He offered to diagnose it.  The tech pulled the spark plugs to run a compression test.  The number three spark plug didn't look so good.  The electrode was smashed, probably by the piston.  Figuring it actually did need an engine, I limped it home and got to work pulling it apart.  At 30mph with the window down, the wind noise drowned out the racket from the engine.

I snapped a picture Tuesday and got to work.  

After some thought, I figured I'd put a new plug in cylinder 3 and fire it up.  It ran for a minute or so, still making the same noise.  I pulled the spark plug out, and expected it would be smashed.  It wasn't.  The old plug is below.  

So still not knowing what's going on, I started prepping to pull the engine. 

I got the driver's side valve cover off, not because it has to come off, but because my curiosity was killing me.  I noticed that the rocker arm for the cylinder 5 exhaust valve was loose.  I could move it side to side enough that it would expose the top of the valve.  All of the others were tight.  When I tightened the bolt, it collapsed the valve spring, as you can see in the photo below.  

So, still confused, I'll press on tomorrow.  I should have a bore scope to get a look at #3.  If anyone has any ideas, I'm all ears.  At this point, I'm still expecting to put a junk yard motor in it, so anything short of that is a win. 

Super long shot, but are the torque converter bolts loose? I've heard that can make bad noises. 

You're going to have to take them out to pull the engine anyways.

Probably a 0.001 percent chance

When you say that the bottom end bearings are fine, how did you verify this? By pulling the pan? I'm wondering if you have a failing connecting rod and it allowed the piston to make contact with the plug. 

If your rocker was loose and you tightened it, start the engine and see how it sounds.  If you tightened it and it made the spring compress then your valve is supposed to be open.  There is no adjustment in the valvetrain, so a loose rocker bolt is bad.  If you put it back together and it’s fine, I would pull the cover back off and look for damage caused by the loose rocker including to the rocker itself, bolt, bolt hole.  If you end up needing just  a rocker and bolt i can priority mail you one.

I would have to agree with Patrick. I think that a loose rocker bolt would have caused part of your issues. The car would run like it was missing on one cylinder and it would make a loud ticking noise (almost a knock).

In regards to the spark plug, the only way I see that as being damaged would be the first shop dropping the plug on the concrete while they were trying to diagnose your car. I can't see your piston traveling far enough to hit it without a lot more damage. Then you would see metal in the oil.

The engine came out yesterday.  Before I could even get it on the stand, I pulled the driver's side head.  I expected to find nothing at all, and then continue to question what could have gone wrong.  I still don't know what exactly did go wrong, but it was clearly something.  This is the #3 piston, the same one that had the mangled spark plug.  Clearly something got in there and did some damage.

The head didn't fare any better.  There were some metal chunks that had been fused to the head.  The big lump at 6 o'clock is the likely offender. 

Interestingly, the #1 cylinder had a booger in it also.  It hadn't done much damage yet, but it was well on its way.  The piston was missing a chunk.

You can see the offending metal at 6 o'clock, right next to the chunk it took out of the head.

Now, the question is: Where did that metal come from?  I haven't found an obvious answer yet.  I'm going to pull the other head and then take a look at the bottom end.  It really doesn't matter, as I'm going to put in a junk yard engine.  But I'm curious how an engine can let go so suddenly without losing oil pressure, over heating or spinning a bearing.  I'm headed to car-part.com to find an engine. 

Side note: after living my whole life in Michigan, I expected most of the bolts on the underside to be corroded and snap as soon as I put a wrench on them.  This truck spent its whole life in southern Arizona.  Every single fastener came loose with hand tools.  I had to oil the exhaust manifold flange bolts, nothing more.  I don't think I'll ever buy another car that's been driven up north.

Wowzers - not what I'd expected! At least you didn't pull the motor for nothing :)

I’ve had bits of piston ring come apart and bounce around the combustion chamber and make a similar looking mess.  

Well, mystery solved.  I picked up a used engine out of a 2004.  I didn't realize that 2003 was the last year with a return on the fuel line.  I also didn't get a throttle body with the engine.  So i spent the day playing Lego with the two intakes, fuel rails, etc.  I don't have the skills or the tools to get the engine in without removing the intake, so it wasn't too much extra work.  As I was rolling the old intake around, I heard something loose in there.  After getting the throttle body off, I could clearly see some metal pieces in the intake.  After some more shaking, I had this.

The piece on the left is the clip that holds the fuel line to the rail.  The chunks on the right are the other clip, the one that wasn't there when I pulled the engine.  According to the prior owner, the knock sensors were changed by the first owner.  That would have been at least 20k miles ago. 

Wha.....  crazy!!

I had the exact same thing happen to our 2002 Avalanche/5.3L. Took it to the dealership for knock sensors (under warranty), picked it up later and only drove 2 blocks before it died. They towed it in, tore it apart over the next two weeks, and found a piece of metal not unlike yours. Wiped out 2 pistons (chipped ring land) and a valve IIRC. They replaced with new piston/rod/bearing assemblies and its been fine for well over 100,000 miles since. 

How does this even happen? Did it fall in when the manifold was off? I can’t imagine there’s any way for it to get sucked in with the manifold and throttle body attached?  Now I feel like I should check to make sure the clips are there in my 6.0 Suburban 

I'm sure it fell in when the manifold was off to replace the knock sensors.  It's big enough that it would take some bouncing around before it could slide past an intake valve.  I'm guessing that leaning against the valve stem for 20k miles would wear it down.  I assume there was enough vacuum to suck most of the small pieces up into the manifold, explaining how metal got into two different cylinders.  All the damage was on the driver's side, the same side as the fuel lines. 

Unfortunately, the cost of the machine work on the head, or rebuilt heads, plus two pistons, and associated labor, is more than a junkyard engine.  I'm just glad I took a look inside before bolting the old intake on the new engine and wrecking it too.  Now my biggest fear is that I didn't get all of the pieces out. 

In reply to G8MikeGXP :

Seems like you've got a challenge-friendly LS on your hands now.  Which LS is it?  I'd pull that piston and rod, clean / deburr / polish the piston, do the same to the chamber, inspect / replace #3 valves, throw gaskets at it, and run it.

In reply to AngryCorvair :

It's an L59, the flex fuel 5.3.  I've already been thinking about what to do with it.  There are thousands of old Chevy pickups running around down here, lots with inline sixes...

Obviously worried that I wouldn't get all of the metal out of the intake, I hosed it out and gave it a three day bath in some Purple Power.  Then I scrubbed everywhere I could reach and hosed it out some more. 

The original had just gotten a new water pump in the last 5k miles or so.  The junkyard motor was probably running the original coolant.  I pulled the water pump and got out the hose.  The amount of rust and orange crud that came out of the water passages was pretty impressive.  I flushed until it ran mostly clear, which was about 10 minutes after I was bored of hosing.  At this point, it was almost ready to go in. 

I figured it would never be easier to change plugs and wires, so I ordered up along with a throttle body gasket, water pump gaskets and intake gaskets.  And the required "box of new parts photo."

I also figured I should take a shot of me where the engine was supposed to be, because that's what you're supposed to do when you pull and engine.  But, I'm pretty ugly and the view from the garage is spectacular, so I turned the camera around.

Wait..... where are you located? That looks very similar to hte inlaws view from their back porch. 

In reply to Bob the REAL oil guy. :

I'm in Sierra Vista, AZ. 

I know a thread is useless without pictures, but there isn't much exciting about a stock engine in an appliance.  Either way, the engine is in and the truck runs like new, or at least as well as it did when I bought it. 

I have a full engine wiring harness plus an L59 5.3 that I have no use for.  If anyone needs the harness, or any other parts, they are your for the cost of shipping.  The bigger bits are probably not worth shipping, even for free.  But if you need something, let me know. 

PM sent regarding the harness 

Edit:  Looks like the email won't go thru...if you don't get a second email, please feel free to message me instead.

In reply to caseyjones :

Got your email.  I'll be in touch.