Premature Bearing wear

Pulled the rod bearings out from the pan. Had a knock it sounded like so i decided to see what was up. heres the bearings that i pulled they were brand new when i rebuilt it. started it it ran fine but before i could get it to start I think i flooded it and the gas seeped through the new piston rings that hadn't set yet. Ran it for a bit maybe 20 mins, changed oil to a break in oil and the original oil had lots of metal glitter and smelled of gas. Changed the oil again after running and driving for maybe 2-3 miles and there was still some glitter and gas smell but less. I think the gas was just residue. So after two oil changes i started to hear a knock after it would warm up. decided to pull the bearings and this is what i got. Very premature wear on all of them and it looks like some glitter got in between and scored the bearings pretty good. not a single one escaped clean. another thing to point out is on the top of each half bearing were the cap and rod meet there is no wear what so ever on any of them. This is what I can't figure out, are the bearings to small? another thing I thought of was a warped or bowed crankshaft. The reason i think it might be a bowed crank is because the wear looks deeper and worse on the middle bearings but the bearings on the front and back look better. Idk what it could be but any help would be nice. thanks. ask any questions you need to help get to the bottom i just kinda through the info on.

 

Did you check the crank for straightness? You may have 'tapered' journals on the crank also. Did you resize the crank end of the rods? How about 'plasticgauge' the rod bearings for clearance when on the crank? You may have to get the crank reground also. It majorly sucks you have a knock on a new rebuild. Good luck

 

Next time take it to a machine shop. They put the rotating assembly together, spin it, then remove and add weight from the crank to get it in balance. And they check clearances.

 

My experience with the 4 Runner engine (3EZ-V) is extremely limited. And I'm not even sure what causes rod knock.

But your report is confusing. Are we to understand that you had a knock to start off with? You can sometimes identify where you have a knock by running the engine and pulling the spark plugs wires one at a time. When you reach the cylinder with the knock, the sound will either change or cease.

And then you say that you had new piston rings as well. So are we to assume that you pulled the pistons, replaced the rings and then the rod bearings as well? Did you hone the cylinders, and if so, how did you clean them of honing material? Did you set your ring clearances correctly? I think it would be a bit difficult to do from the bottom of the engine.

Did you see any metal particles in the oil before you started? And what did the original rod bearings look like?

Did you use assembly lube on the rod bearings when you replaced them?

I don't think flooding the engine and having excessive fuel leaking down the cylinder walls would normally cause damage to the rod bearings. They get their oil indirectly from the sump and through the crankshaft. More likely the rings and cylinder walls would suffer damage. I normally lube the rings and cylinder walls with oil during the build. And I use a paste lube for the bearings. And I use a dyno oil rather than a synthetic oil at start up.

To me, and assuming that you had proper clearances, your bearings look like they may have had inadequate lubrication - especially the ones with what appears to be scraping damage in the middle of the photos. The striations would be from the metal particles in the oil - but I don't think the metal you are finding came from the new rod bearings. Assuming they are multi-layer bearings, they do not appear to have worn through the outer tin layer. I think you probably have a failure somewhere else in the engine.

Regarding your observation that the bearings have no damage where the bearings meet, this may have to do with the concept of bearing crush. But I don't think it is evidence of any problem. I've rebuilt a few MG B series engines and the greatest wear has always been in the center of the bearing, and especially in the rod cap bearing. I recently replaced the rod bearings on a 50,000 mile Honda S2000 engine and found that the greatest wear was in the center of the bearings on the rod side, not the cap side. In any event, I think the wear is related to what part of the bearing receives the greatest impact during the firing of the cylinder.

Good luck.

 

Bad rings, getting fuel in the oil, breaks down the oils viscosity quickly. A bad oil pump or bad oiling system wont allow adequate oil to get to bearings and when you starve those parts of oil you trash the engine. Getting fuel in the oil breaks the oil down which can also cause metal to metal wear.
Watch this video, its a good one.
Engine builder builds a custom race prep 3.5 ecoboost with pistons, rods, fancy coated bearings, cams, gears, ect ect ect. Customer has it installed in his Raptor and before they can even put it on a dyno they hear knocking. Engine was sent somewhere else to diagnose. Engine disassembly shows the engine builder forgot to tighten down the oil pump bolts, which allowed the oil pump to push the oil right back into the oil pan and not thru the oil galleys.

https://www.youtube.com/watch?v=Dr1-JE4Uj8o

 

OK, now I saw your prior thread and listened to (watched) your video. And I suppose I have a better understanding of the history. I'm thinking that you did not have rod knock, but something else in the rotating mass that is getting metal shards into your oil - which probably means you need to strip down the engine. It sounds front end, but the timing belt is external to the engine. I assume you did not find any loose rod caps when you pulled the rod bearings. See https://youtu.be/7f7Jm8m-W-s?si=UKVIMZVoprbtUVtk

 

The bearing wear could have been caused by lack of lubrication. Possible dry start?

I have rebuilt a few engines over the years and this has worked for me.

Always use an Assembly Lube. Make sure all of the top and bottom end components are coated with the lube.

Before the first start, remove the spark plugs and fuel pump fuse. Crank the engine over until you see oil pressure on the gauge.

Reinstall the plugs and fuse. Start the engine and immediately bring the RPM up to 2k. This will assure full oil pressure and enough rotation to sling the oil around. Not all of the components are pressure lubed, some are splash lubed. Hold the RPM until the water temperature is up to normal. Shut it down and look for leaks and check the fluid levels.

For the next few hundred miles vary the speed and RPM, try not to exceed 3 to 3.5k. Once it is broken in, go for it.