The video every 3rd gen owner wanted.

Great information. I saved it for future reference.

But, holy shit, could they have made the lubrication system any more complicated? Trying to follow that diagram makes my head hurt.

 

I have no formal mechanical qualifications, just what feels like a long time wrenching on things (so take this with a grain of salt) but that sure looks like an oil starved bearing to me. What’s more, none of the surrounding bearings look bad. To me, this suggests that the oil supply for that specific bearing is bad, either because of debris blocking oil flow or because of a design issue, or both. Based on what I’ve seen and read, Toyota’s explanation seems entirely plausible to me.

Now, if the new engines start eating that same bearing and there is no debris issue, well then I’d say there is more to this problem.

 

Because there have been failures well AFTER the stated debris fix timeline, (although they seem to have dropped off in frequency) I'm falling into the "both" camp.
Debris: Leftover machining burrs from oil passage drilling intersection just ahead of main#1 let loose, make their way to main #1, and grind it into oblivion.
Design: Main #1 not being captive, walks forward, blocking oil passage, smoking main#1 and/or spinning it.
2 different failure modes, same end result at the same place.

 

If it was oil starved, wouldn't one of the back bearings go first, I believe we've seen the oil flow diagrams and CCN alluded to the flow moving front to back.

 

who the hell knows, lol

toyota and nobody else.

but we can speculate for entertainment

 

Best speculative answer I've heard so far.

 

Those bearing tabs are basically for assembly and orientation, they don't "hold" the bearing in place. Proper clearances and torque hold the bearings in place. If there was any "machining debris" I think it was in the main cap bolt holes preventing proper torque and bearing crush on front cap. Or more likely a miscalibrated robot over or under torquing the main caps.Oil system flows front to back in these engines.If you spin the front main, it will stop oil to it and the rods fed by that main, the other mains will still get oil from the oil galley, according to the diagram.

 

This is the kind of rant quality I've come to expect from this community.

*opera clap

 

Futile catharsis.

 

But cathartic nonetheless.

It was a well worded rant. Props to you sir.

 

I am here for the fun. I no longer have a dog in this fight since I got rid of my tundra. So I guess I will root for my new project that's better than all yours. 98 Silverado Z71. It's nice to be able to change a starter in under 30 mins. Replace front wheel hubs and cv axle in about an hour each. Also how insanely easy and cheap it is change the alternator, PS pump, A/C comp and water pump. Obviously not in the power range that my SCed tundra had, but it's just to tow the boat and throw trash away. As for my new ride, decided to go to the "luxury" suv side. Bought a 2025 Acura MDX SH-AWD. Wow, I cant believe what I have been missing ride wise. I could have done this before. Beater truck and a nice suv, best of both worlds.
Still trying to get rid of some tundra left over stuff and still frequent the site for a few laughs and to see for future references what's the biggest tire I can fit without a lift or what oil is best threads. Any day now, Toyota will figure it out.

 

Except there are no main caps.

 

But there are, they are just incorporated into a girdle.

 

^^^And this is why I believe the girdle design is flawed.

I'm certainly no mechanical engineer, but IMO there's no way to get consistent oil tolerances on every main bearing when the caps are built into a aluminum girdle that is held in place by bolts around the perimeter of the girdle. In a tradition engine, the main caps each had 2 bolts. The girdle design uses half the number of bolts to do the same job.

To me, it seems like the girdle design made the automated assembly procedure easier, at the expense of precision.

 

Bingo! And is the same system Hyundai use on their 2l Turbo in the Santa Fe's. Our daughter's Santa Fe blew up in the fast lane of a 4 lane highway and she managed to pull over safely. Hyundai used the same excuse for those motors, machining debris. They replaced the motor but she didn't keep it long enough to know if the new motor was going to last.
Could that be why some trucks are fine? They get lucky and end up with a properly torqued girdle, but the odd one doesn't get torqued properly for whatever reason and they are the ones blowing up.

I too am no mechanical engineer but personally suspect the girdle design is for efficiencies and not necessarily using best engine building procedures. For those of you who have built / rebuilt your own engines, what choice would you make when trying to bullet proof your motor? Girdle or individual bearing caps?

 

The girdle would be torqued in place and aligned bored and honed to finished size and diameter prior to assembly, but if it was incorrectly torqued prior to machining or assembly, who knows? Just my personal thoughts of what could have possibly caused the recall issue. Could be i'm out in left field on this, sure would be nice to know what the actual cause was, if only to satisfy our curiosity.

 

Is things like this why the term KISS came from. Just like the CAN Bus, all it takes is 1 thing to go offline to make the whole vehicle inoperable.
When I was looking for my new SUV, I only had 2 contenders, Lexus and Acura. Lexus was automatically eliminated when I found out that the RX350 no longer comes with a V6. I previously had a 23 Acura RDX, 4cyl turbo. The 4cyl in a bigger SUV doesn't inspire confidence. The V6 in my MDX is so smooth and no 4cyl can duplicate that.

 

Watch the video closely. We have large hardened 4 bolt mains just like older engines aside from the small girdle bolts. As I see it the girdle just allows them to drop in all the caps in one move. Then they torque the crap out of them.

 

But the torque specs for our big block Chevy on the main caps is around 65 lbs. Why did AMD need a 5-foot breaker to free the bolts? Something is definitely wonky.

 

1950’s engine design vs. 2015ish? Didn’t bother looking, maybe the V35A uses TTY bolts.

 

Still running on original motor 75 years later. Whose gonna post a pic of a V35A Tundra in 75 years.

 

Not 75, but 30 years later, still running strong. And one in my boat thats 25 years old. That one is at 4+k rpm 80% of the time.

 

Yep, good old SBC's. Hard to beat 'em.

Sidebar: That is the wonkiest looking air intake/snorkle assembly ever.

 

This one has the Spider Injection system. Throttle body on top of intake manifold.
Got reminded to turn on the boat engine. This one is regular TBI.

 

Still good for 1300hp and 1200lbs tq.