Official S65 Rod Bearing Condition Example Thread

Assimilator1 wrote

Whilst I do agree that lead/copper bearings typically come out looking worse, and I also believe we haven't seen any tin/alu/copper bearings that have worn down to copper so far, but I wouldn't call the wear to the tin/alu bearings as merely discolouration.
There is physical wear happening to those bearings, not just deposition of (say) carbon on the shells, the shells micro grooves are often seen to have be worn, or even completely smoothed out. As can be seen in the 3rd and 4th photos in Deansbimmer post here and by these excellent quality photos by Ximian (the lower ones).

The point about discoloration wasn't a suggestion that the newer bearings don't wear. That'd be ridiculous. The point is that the discoloration we've seen doesn't mean critical wear, unlike what we've seen on the earlier bearings.

Not seeing copper doesn't mean the wear is insignificant; just that it's not critical. Per what I've heard straight from Glyco, even having the grooves partially worn away is most likely not critical. Significant vs. insignificant is a value judgment that depends on your criteria.

Either way, the original question was whether the new bearings wear less than the old ones. Apparently the answer to that is a hard yes.

Fair enough, and agreed, but in which case it'd probably be best to steer away from using the word discolouration

Assimilator1 wrote

Fair enough, and agreed, but in which case it'd probably be best to steer away from using the word discolouration

I get that. It might give the impression that nothing significant is happening, when in reality that may or may not be the case.

To be clear, when I say discoloration, I'm talking about the color specifically, not the wear state. If you can think of a better term for a thin film of oxidation right on the surface that technically correlates with wear but isn't wear per se and doesn't itself suggest a severe problem, feel free to suggest.

It's not just oxidation though, at least in some (many?) of the cases the micro grooves are physically worn away (as per some of the photos I linked on the 11th), this is wear.
But agreed that is not a severe problem at that level of wear (that we've seen so far).

Assimilator1 wrote

It's not just oxidation though, at least in some (many?) of the cases the micro grooves are physically worn away (as per some of the photos I linked on the 11th), this is wear.
But agreed that is not a severe problem at that level of wear (that we've seen so far).

Layne's Law: Every debate is about, or eventually degenerates into, debating the definition of a word.

You're saying there are multiple things going on in the newer BMW bearings as they wear – the color change, the grooves being worn away, etc. – and you're saying the word "discoloration" doesn't cover it all. You are correct. I agree.

I'm saying the word "discoloration" describes one of the things happening to the bearings as they wear. One of the things. Not all the things. Just one of the things.

People thought the discoloration on its own necessarily meant the bearings were showing copper. As we discovered, it does not. This is why the discoloration is worth singling out: people thought it necessarily meant critical wear, which it doesn't.

The discoloration plus the grooves being worn away does indicate some wear, as you say. Though, per Glyco, not even that is critical.

Better?

New member here and i look forward to learning from everyone.

So I've have a 2011 M3 E92 Competition DCT I purchased on BAT May 2022 with 39,250 miles. The seller had a Blackstone report done 2/20 and I attached the report. See comments. I've has the throttle actuator replace in March of this year 2023. My question is should I consider doing the rod bearings now or wait. My current mileage is 43K. The only mods have been a Dinan Catback exhaust. Thank you!

bere223 wrote

New member here and i look forward to learning from everyone.

So I've have a 2011 M3 E92 Competition DCT I purchased on BAT May 2022 with 39,250 miles. The seller had a Blackstone report done 2/20 and I attached the report. See comments. I've has the throttle actuator replace in March of this year 2023. My question is should I consider doing the rod bearings now or wait. My current mileage is 43K. The only mods have been a Dinan Catback exhaust. Thank you!

The only way to track your bearings through oil analysis is doing it every change since brand new bearings installation (or brand new engine). That's because the layers come out from the bearing not immediately before blowing engine, so you never know if one isolated good oil analysis really reflects the health of the bearings.

So, yes, you should replace your bearings now.

Go with BE Bearings and BE-ARP bolts, and you'll never have to make oil analysis or change bearings again.

Congrats for your purchase, I'm sure you're already in love with the car, and probably will stay like that forever.

bere223
You might want to read the link in my sig re oil analysis and rod bearing wear.

Whilst tin/alu/copper rod bearings would seem to be at a lower risk of disintegrating than the earlier OEM lead/copper ones, the risk isn't zero (or as near zero as any engine can get). Engines with both types of bearings have failed, although more of the earlier bearing type have failed (so far).
Also the harder material of the later bearings could make damage to the crank more likely if things do go wrong (no idea how much more likely though!).

BE bearings are great bearings and come pre-measured with the right amount of extra clearance needed, but they aren't the only choice.
An alternative is ACL bearings mixed set and (must be) 'hand' measured, my understanding though is the price saving between that and BE bearings in the US is small (not so here in the UK!). The only place I'm aware of that sell hand measured bearings to the public is Mporium (a sponsor here).

Might be a dumb question but once the rod bearings are done do you still need to follow a religious warm up procedure? I.e letting car hit 210 before getting on it? Or do you have more leeway.

rjsiciliano wrote

Might be a dumb question but once the rod bearings are done do you still need to follow a religious warm up procedure? I.e letting car hit 210 before getting on it? Or do you have more leeway.

I think one always does, but if he doesn't sometime, it will not harm the engine so bad as before.

Driving with a bit of mechanical sympathy and allowing an engine to gradually come up to temp before putting the hammer down will always benefit an engine. Especially high output engines with tight tolerances, remember we typically do NOTHING with the mains in these cars and their tolerances may be tight as well.

spammysammich wrote

Driving with a bit of mechanical sympathy and allowing an engine to gradually come up to temp before putting the hammer down will always benefit an engine. Especially high output engines with tight tolerances, remember we typically do NOTHING with the mains in these cars and their tolerances may be tight as well.

Ow, that's a powerful argument. Main bearings, well mentioned!

Assimilator1 wrote

Also the harder material of the later bearings could make damage to the crank more likely if things do go wrong (no idea how much more likely though!).

Can we talk about this as well? I have questions, and not the rhetorical kind.

How does the harder material pose a greater threat to the crank? Has this actually been seen to happen? And/or what are the possible mechanisms for that to occur?

I get why this is a sticky idea. Harder = more likely to scratch a given thing rather than be scratched by it. But any bearing material will be way, way softer than the crank. That's literally the point of a bearing material. No one is stupid enough to spec a bearing material that's hard enough to damage a hardened steel crank on its own.

Probably safe to say it's also not a matter of these bearings wearing down to the backing sooner, because we now know the opposite is true.

Reduced embeddability, maybe? More crank-scoring debris floating around? If so, how could the un-embedded debris score the crank without first annihilating the bearing, which doesn't show up much if at all in the pics?

I know harder bearing alloys can have less conformability, which could generate hot spots and inconsistent oil films. Is that it? But if that were happening at scale, wouldn't we see a lot more worn bearings, failed engines, or both? And, as the Glyco document repeatedly cited in this thread says, tight clearances actually improve conformability via very slight, highly localized initial wear – which lines up nicely with what we now know we're seeing in pics of these bearings...

40000km/25000mi

Motor changed in 2015 at 61000km, previously changed at 28000km, it's its third motor... 702/703 bearings, oil service every year at max 10000/km

quite disappointing big fear on the number 4, fortunately the crank has nothing

What do you think about all the little blacks points? that's strange

oil pan inspected it's like new, i'll open and cut the oil filter soon

--Aramis-- wrote

What do you think about all the little blacks points?

nothing to worry about, that's normal.

all the previous engines were blown due to rod bearings?

On the bills of engines changes it said in swedish "engine KNACKAR" likes engine knock

So it seems it's a rod knock

At second change at 61000km they have changed the oil cooler and all the oils pipes, perhaps first time some debris stays in the oil cooler and destroy the second engine...suppositions

i have mounted BE bearing they have some marks also, i suppose about the mesurement process, but it's not reassuring first time you see them

--Aramis-- wrote

i have mounted BE bearing they have some marks also, i suppose about the mesurement process

Yes, they are. Your engine should be fine now.

I lost an engine too (fuel hydrolock) and reused all parts that were not part of the "short engine" diagram, like the oil filter housing, oil pipes, oil cooler. There were some debris/metal shavings in one or two oil changes after that.

Checked the rod bearings twice too, no problems with them then.

a BE shell had a small dent on the outside (really small 0.5mm), may be due to a fall or a shock, I softened it very slightly to no longer feel it when the finger passes over it,

i wish all will be okay when i restart the motor, i really dislike this kind of job...

--Aramis-- wrote

a BE shell had a small dent on the outside (really small 0.5mm), may be due to a fall or a shock, I softened it very slightly to no longer feel it when the finger passes over it,

i wish all will be okay when i restart the motor, i really dislike this kind of job...

Have any picture of the before and after doing that to the shell?

You could send it to @Green-Eggs, or Robert Collins on Facebook (https://www.facebook.com/robert.collins.79827) and see what he says. They are co-owners of BE Bearings (I still don't know if they are the same person or not).

Green-Eggs

unfortunately I forgot to take a picture, I'm sorry

it was really minimal

a shell also had glue on it, i removed it with alcohol

edit :

I made a photo montage of what it was



after softening it i can see a little starting of copper

i don't know if it's possible to buy just two BE shells, on up and one bottom, if it's possible i'll will change this one

BE ARP bolt are reusable? i could remove the shell and take picture

I hesitate to replace it but it needs to buy a new complete shells kit

Green-Eggs have you some advice?

I thought it through

I have re ordered a complete set, i will change this shell, i don't want to take any risk

I'll post picture of the shell with dent

It's a pita because in Europe we have to order in US directly with customs and VAT, It's a tax hold-up...but it's another subject