Okay, as a longtime data geek and mechanical moron, this video had me enthralled. What was it all about? Some guys asking themselves “Why?”
This brand new L87 engine with ZERO miles never even made it into a vehicle before it was condemned by GM. It failed one of their quality control Pico tests and we want to know why. In this video, we tear it down, take some measurements, and run tests to uncover why it was tossed in the trash — and how this single engine design ended up costing GM over a billion dollars in recalls and warranty repairs.
I don’t have the faintest clue what any of the technical pieces or terms are all about, but the search is absolutely thrilling. It’s when these mechanics start looking at the data gathered from analysis of the different engine components that my inner data geek gets excited,
It’s the kind of stuff I used to do at The Great Big Research Company in my initial job in the Stat department: picking at the data, looking for stuff which shouldn’t be there and is, and/or stuff which should be there and isn’t.
My favorite quote: “These are big numbers. Are they big enough to ruin an engine?” (He’s talking about a hundred thousandths of an inch, which in the real world would scarcely matter except when you’re looking at precision-made machinery.)
I’m not going to post a spoiler, here, but it involves the level of chamfering around some holes.
What I truly love is the level of expertise shown by all the guys in the video — and when they bring in Dave himself, his explanation of the problem is absolutely brilliant.
Go and watch the video. It’s half an hour out of your day, and I promise you that you won’t be disappointed. Even if you’re not the slightest bit interested in the minutiae of engines — which would make you similar to me — the journey is worth the time.
That is an interesting video. As a machinist/mechanic/aircraft mechanic They are getting deeper into the technical details than I ever had to go, but surface finish is very important in the kinds of bearings they are looking at. I probably never used a surface finish measuring device that went beyond the Ra they are talking about, but for what they are analyzing the Rz would certainly be important. The way surface finishes are measured and characterized should be right up your professional alley as it (RMS) is very much a statistical measurement.
It all comes down to oil pressure and flow and those big chamfers on the oil passages are not helping things any, but I’m guessing the surface finish issue is more important. If I were still working in industry, I’d be looking at the details of their grinding and polishing procedure. I’d be looking at the type and grade of grinding wheels, how often those wheels are being dressed, what kind of fluid is being used during grinding, and similar questions about the polishing process.
Yes, and that trash in the oil pan isn’t helping any.
If you’ve never seen an engine come apart, that process alone is enough to recommend watching this video. Live Engine Teardowns sessions were always the most popular Tech Sessions that we ran for the Porsche Club in the days before You Tube. We cheated, of course, because disassembling a 100,000 mile engine is a time consuming process and something always doesn’t want to let go. We wanted to keep the presentation to under 2 hours so we reassembled an engine loosely before the class so we could demo certain problem areas.
As a Degreed Mechanical Engineer, I would agree with the conclusions and add that it’s maybe not the amount of chamfering as it is the shape of the chamfer. or maybe using higher weight oil. Or some of each. Further testing is needed to find the source of all that contamination in a low hour engine.
Heh. Loosely assembled.
https://www.youtube.com/watch?v=h-wZ43NVL7E
We had a surplus WWII jeep on our ranch when I was a young sprog. I learned to drive it solo by age 8. That came in handy later when I was in uniform.
Right ……. Kind of like that.
We just used enough hardware to hold it together so when it was on the engine stand at the start of the session it looked like it had just been removed from an air cooled 911, still fully dressed with all the accessories.
Just as long as no one attempted to turn the crank. An air-cooled 911 engine is an interference engine. If the chain driven Overhead Cam timing is not just right the pistons will hit and bend the expensive sodium filled vales.
……. and thats just for starters.
When dad was in the Air Force he was a engine mechanic. His primary job was to Nichol plate engine parts and polish them.