What killed my S70 T5M... Place your bets

[WhatAmIDoing]

So for those who don't know. My beloved 1998 S70 T5M died a slow and inevitable death at 323k miles. About 30k miles ago I started noticing brass/bronze flakes in the drain pan every oil change. She was down on power and burning a lot of oil. I did my best to investigate using non destructive means, but I couldn't find a smoking gun. In the middle of my trip to go look at a V70, going up a steep hill, I started feeling a bad vibration like a failing tire. I let off and the vibration went away. I accelerated and it got worse. The CEL started flashing and I coasted to the next exit. I got out and she had a definitive miss on one cylinder. Under the hood I could hear a clacking sound. I shut her down and had her trailered to a location I can store it at for the winter. Come this spring I will tear into the engine and discover what failed. Place your bets!

But why would you keep driving it if you knew it was exhibiting symptoms of severe engine problems?

Sometimes you just don't have a choice. Used car prices were (and still are) extreme and I have a lot of driving to do every day. Every time I had the opportunity to buy another rig, the seller would flake out. It is what it is.

I did my due diligence to try and find the root issue. I even had the oil tested and the lab said all wear metals were normal or below average. It never lost oil pressure. I poked around with a stethoscope and couldn't find any bad noises. Other than some brass flakes, there was no bad behavior keeping me from driving it. And like I said, I couldn't find a replacement daily and I had to drive.

[scot850]

Burnt valve(s) and main bearing failure.

Neil.

[MoVolvos]

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"brass/bronze flakes" - ? "Confirming the color and type of shavings in your oil is the best way to decipher what has failed inside the engine."

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[WhatAmIDoing]

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"brass/bronze flakes" - ? "Confirming the color and type of shavings in your oil is the best way to decipher what has failed inside the engine."

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Machinest buddy said it looked and felt like brass to him. I agree. Definitely gold in color. Oil lab said they couldn't detect any meaningful levels of wear metals.

[Sveedy]

I must be missing something here. Both you and your machinist see particles large enough to see, feel, and identify, but the lab doesn't see anything out of sorts ??

[WhatAmIDoing]

I must be missing something here. Both you and your machinist see particles large enough to see, feel, and identify, but the lab doesn't see anything out of sorts ??

You would be correct. I used a very well known and popular oil testing laboratory. Probably not gonna waste $30 on that again.

[erikv11]

Oops - I thought we were supposed to guess before reading the description! Good luck with the transplant ...

[abscate]

It is entirely possible that you could have ground up something brass without getting trace metals in the oil

[volvolugnut]

It is entirely possible that you could have ground up something brass without getting trace metals in the oil

I can see how this might happen, but I can't give a guess what the brass thing might be. You might find it in the bottom of your oil pan.
volvolugnut

[Sveedy]

Well crack an egg of knowledge on me, because I can't see how it's possible.
Sure you could put some shavings of metal in a vat of oil, fish them back out, and not show any metals in the oil upon testing. But run that same oil through an engine, and I would think that some bits would get ground up in the bearings enough to show up in the test. Put another way, would you actually use oil that you found metal shavings in, regardless of a test result ? I know I wouldn't. Just doesn't add up.
Also bronze, not brass, is what is probably being seen. Seeing it at every oil change also leads me to think bearings.