LM7..Puking metal, but runs great?

Joined
Dec 10, 2023
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65
Hello all.

Been having a bit of an issue with my 5.3 in my Tahoe as of late.

Picked it up for cheap from someone who didn’t need it. It had 240K, figured if it ran well, mine as well give it a shot.

Long story short. Did my first oil change at around 243-244K, after he did one at 241. Noticed some metal in the oil, but i originally wasn’t worried because i thought it was leftover metal from the drain plug being stripped and needing to be replaced with one of those oversized ones.

Drove it until around 247K, dropped the oil again, at first didn’t see anything till i got it in the sun. The oil had that metallic sheen to it and looked like metallic brown nail polish.

Drained it from the container, bunch of what looked to be metal “crumbs” (i don’t know how else to put this) in the bottom of the pan. My phone was dead so i couldn’t take any pictures before i drained it and gave it to Oreillys for recycling.

It has fantastic oil pressure. It has some piston slap that it’s always had cold, but it goes away quickly when it starts to warm up. It runs smooth as silk. There are no other issues than this. For reference, idle oil pressure cold with 5W-30 in around 105°F ambient temps is around 45-47 PSI. When it’s hot it’ll hover around 35-37.

I haven’t driven it since around 7/25 now because frankly i just don’t want to do anymore damage. I’ve asked around and i’ve gotten answers telling me it’s going to explode tomorrow but not any actual help or diagnostic tests.

Lastly, from what i can tell, it’s REMARKABLY clean inside the engine. With a borescope camera in the passenger head it looks clean enough to eat off of.

Any help would be greatly appreciated. Thanks.
 
Drained it from the container, bunch of what looked to be metal “crumbs” (i don’t know how else to put this) in the bottom of the pan. My phone was dead so i couldn’t take any pictures before i drained it and gave it to Oreillys for recycling.
Cut the filter element out of the oil filter and pull it out flat. If there is metal, you will see it.
 
Gen III engines can & will eat a lifter, My 2000 Silverado was got cheap because a eaten lifter/damaged camshaft LM7.

Change the oil & keep truckin' while you find a LQ4 6.0L.
Goal right now is to change it again at 500 miles and see what happens then with the metal in the oil. Just as bad or worse, she’s getting taken out of service for a bit.

How hard is a 6.0 swap? I do not want a 4L80.
 
Goal right now is to change it again at 500 miles and see what happens then with the metal in the oil. Just as bad or worse, she’s getting taken out of service for a bit.

How hard is a 6.0 swap? I do not want a 4L80.
I am replacing the engine in my other truck at the moment. Do not like the timing of this, lol
 
Goal right now is to change it again at 500 miles and see what happens then with the metal in the oil. Just as bad or worse, she’s getting taken out of service for a bit.

How hard is a 6.0 swap? I do not want a 4L80.

Use the flexplate off your LM7...The end. ;)

But, Seriously just stay away from early '99/'00 iron headed/extended crank LQ4.
 
Pushrod tip wear is quite common on high mileage LS engines, Requires replacing the affected pushrods & mating rocker arms.
Is this an example of normal wear for a high mileage unit without a problem (except for internal coolant leak)?

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I've had oil that looks like it has a metallic shine but it's almost an optical illusion
 
Get a UOA so the metal will be identified. Then you will have a better idea of what's going on.

But even if you know exactly what the metal crumbs are from, what are you going to do? Rebuild the engine?
 
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Get a UOA so the metal will be identified. Then you will have a better idea of what's going on.

But even if you know exactly what the metal crumbs are from, what are you going to do? Rebuild the engine?
I found out what they were.

Lifters are failing, so i was wrong with what i said before. I don’t have the time right now to swap an engine, so im going to replace the lifters and pushrods and maybe get a better cam while im in there.

For those wondering, it started to tick. Not loud, but enough for my ears to notice. Looked around. Noise is 1/2 speed of crank RPM. Found a few videos of LM7s with failed lifters that had the exact same sound.

Pulling the heads soon. If there’s too much block wear from piston slap, i’ll just slap it back together and drop in a reman engine eventually. But i doubt it, this mf runs GREAT!

Not to mention, i know it’s too thin of an oil, but im still managing to get 50psi of oil pressure at idle using 0w30.
 
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