Just changed out rod bearings at 59k...

[modkrazy]

Originally Posted by CSBM5

The upper shells are the ones that wear most on *all* motors. It's simply due to combustion forces pushing the piston/rod downward on the power stroke. These don't look too bad in the above pictures, but it's definitely good they were replaced especially since the new bearings are the lead-free ones which open up the gap a tad and greatly increase eccentricity compared to the earlier bearings.

From the bearing thread, the change of bearing material had no positive effect. In fact, it is now harder to track damage since you won't get lead levels, and the harder bearings are harsher on the other internal components. They certainly didn't increase the clearance with the new bearings.

The failures seem to be random, and I am willing to bet can be attributed more to build quality and fitment issues at the factory than anything else. Which, of course, could mean some people will tear out perfectly fine bearings.

Surprised OP decided to go for OEM bearings.

[chris719]

The lead free bearings seem to be less tolerant (no pun intended) of a bad stack. A few low mileage 2011+ cars have had spun bearings where it seems to be incredibly rare to see a low mileage failure with the leaded bearings.

[pbonsalb]

Originally Posted by modkrazy

From the bearing thread, the change of bearing material had no positive effect. In fact, it is now harder to track damage since you won't get lead levels, and the harder bearings are harsher on the other internal components. They certainly didn't increase the clearance with the new bearings.

The failures seem to be random, and I am willing to bet can be attributed more to build quality and fitment issues at the factory than anything else. Which, of course, could mean some people will tear out perfectly fine bearings.

Surprised OP decided to go for OEM bearings.

There are presently no bearings available other than OEM.

I have yet to see a set of perfect bearings come out of a car posted here. Maybe there are some others that are perfect that have not been posted. Mine were among the better ones, but still showed more than expected wear in 4 upper shells and a tiny bit of copper at the shell edges on a couple. It was not something I wanted to worry about, even though the percentage of engine failures is very, very small. Plus, it was a good DIY project.

[CSBM5]

Originally Posted by modkrazy

From the bearing thread, the change of bearing material had no positive effect. In fact, it is now harder to track damage since you won't get lead levels, and the harder bearings are harsher on the other internal components. They certainly didn't increase the clearance with the new bearings.

The failures seem to be random, and I am willing to bet can be attributed more to build quality and fitment issues at the factory than anything else. Which, of course, could mean some people will tear out perfectly fine bearings.

Surprised OP decided to go for OEM bearings.

Reread the thread. The static clearance was slightly increased. In addition the eccentricity of the bearing was *dramatically* increased which results in the ability of the oil film to support higher loads at high rpms coupled with decreased thermal loading (i.e. temperature gradient in the oil squish is reduced). This is the primary reason BMW superseded the part number even though, legally, they could still sell the original replacement bearing for the older S65s.

I agree on the likely issues -- tolerance stackup likely plays high on the pecking order.

[modkrazy]

Originally Posted by pbonsalb

There are presently no bearings available other than OEM.

There are the VAC coated bearings, which should at least theoretically be better. Since you do this as a DIY, you can just swap every ~50K miles, so you're good to go.

Originally Posted by CSBM5

Reread the thread. The static clearance was slightly increased. In addition the eccentricity of the bearing was *dramatically* increased which results in the ability of the oil film to support higher loads at high rpms coupled with decreased thermal loading (i.e. temperature gradient in the oil squish is reduced). This is the primary reason BMW superseded the part number even though, legally, they could still sell the original replacement bearing for the older S65s.

I agree on the likely issues -- tolerance stackup likely plays high on the pecking order.

Whatever the intent with the new bearings, it doesn't seem to have had any actual effect based on reported failures.

[CSBM5]

Originally Posted by modkrazy

Whatever the intent with the new bearings, it doesn't seem to have had any actual effect based on reported failures.

From an engineering perspective, as opposed to a non-scientific sample in an internet forum, there is zero basis for that conclusion.

[modkrazy]

Originally Posted by CSBM5

From an engineering perspective, as opposed to a non-scientific sample in an internet forum, there is zero basis for that conclusion.

Anecdotal evidence is still evidence.

[Rupes]

Originally Posted by chris719

This guy himself has fixed up 117 S85s due to bearing issues. That's not a big BMW dealership or well known shop either.

Sounds like a nice little business! Not saying that's the intention here, but of those 117, how many of them "needed" to be replaced due to failure? My guess is very few. Although, some may have been on their way out, no doubt about it. I'm interested to know how bad is bad. We see all these worn spots which don't look good, but how long can an engine operate normally with the wear the OP demonstrated? I would think if the wear continued in a similar fashion, he could have had 100k+ miles with no issues.

[CSBM5]

Originally Posted by modkrazy

Anecdotal evidence is still evidence.

Well, perhaps to those with no engineering background nor desire for actual truths I suppose.

[modkrazy]

Originally Posted by CSBM5

Well, perhaps to those with no engineering background nor desire for actual truths I suppose.

It works in medicine. Fact is, MORE 2011+ cars have reported bearing failures and often at lower mileage than <=2010 cars. I wish it weren't true. Mine is a 2011.

[CSBM5]

Originally Posted by modkrazy

It works in medicine. Fact is, MORE 2011+ cars have reported bearing failures and often at lower mileage than <=2010 cars. I wish it weren't true. Mine is a 2011.

Well, it doesn't work in engineering world unless you'd like to have planes and bridges built that way. You do know that NONE of these "figures" were even bothered to be normalized to production imported, right? For example there were five times as many 2011 E90 M3s imported versus 2010 models as just one example of how distorted data presented appeals to the natural biases of owners. Just by the nature of the numbers in the sample, if everything else is held constant, we should see two times as many 2011 fails as 2009 models, and five times as many 2011 fails as 2010 models. Since 2008 and 2011 model imported are close to even, they should eventually be about the same (assuming nothing changed).

This is only the beginning of professionally looking at the raw data...

[W///]

Originally Posted by CSBM5

Well, it doesn't work in engineering world unless you'd like to have planes and bridges built that way. You do know that NONE of these "figures" were even bothered to be normalized to production imported, right? For example there were five times as many 2011 E90 M3s imported versus 2010 models as just one example of how distorted data presented appeals to the natural biases of owners. Just by the nature of the numbers in the sample, if everything else is held constant, we should see two times as many 2011 fails as 2009 models, and five times as many 2011 fails as 2010 models. Since 2008 and 2011 model imported are close to even, they should eventually be about the same (assuming nothing changed).

This is only the beginning of professionally looking at the raw data...

+1

That is just as stupid as trying to extrapolate how rod bearings and climates correlate when most of the cars/members here are in California (IMHO of course)...

[Rupes]

You'd think at this point some conclusions could be made based on climate, model year, drive styles, warmup times, frequency to redline, DCT vs. manual, supercharged vs. N/A, etc. but it all still feels like a bunch of speculation. You've got very careful guys with issues, and guys who have used and abused the car with no issues. It would be great if we could compile all the data we have thus far and start drawing some conclusions. Minimally, we should be able to find out about supercharged, model year, location and transmission without a lot of follow up. I guess the rest probably depends on (unreliable) owner information and a small sample size. I mean, even if you beat the crap out of the car, would you admit it on a forum pending a new possible engine from BMW? I think not.

[SenorFunkyPants]

Originally Posted by CSBM5

Well, it doesn't work in engineering world unless you'd like to have planes and bridges built that way. You do know that NONE of these "figures" were even bothered to be normalized to production imported, right? .

Wrong...the failure rates are calculated as a function of import production numbers for the USA/Can. Also as a function of mileage at failure. The failure rate as a function of climate was equally "normalised" using the best estimate on ownership by state. True they are small numbers but thats what there is to go with.

Graph showing fail rate relative to production numbers and mileage at fail.
Excludes Supercharged cars.



Notes
Av Miles is the average mileage at failure for cars by year. As expected the average falls by year.
Prod#/Fails is the total M3 production number for that year(s) divided by number of failures. The slope of this graph line should follow that of the Av Miles but instead rises at the approximate time that the bearing revision is made indicating that the revision has had a negative effect (There was a main bearing revision in 2008 and a rod bearing revision in late 2010 early 2011. ).
This as of Aug 2014

[CSBM5]

Excellent job for normalizing to production imported volume. One missing ingredient in the conclusions drawn above is that you have good data on early life failures of the 2008 models. I haven't seen any evidence of that since this whole ballgame got started way after start of production of 2008s, years after. BMWNA is probably the only source for this data as they know exactly how many S65s they've replaced under warranty, the mileage at time of failure, the climate the car resided within, etc, etc. I wouldn't trust inferences on the data you have shown about newer model years compared to past ones without the actual complete data.

[SenorFunkyPants]

Its not a great deal of data but what there is goes against several common held positions. It is tempting to believe that the elevated bearing wear we see could be ameliorated with more clearance or a thinner oil but what data there is, infers not.
Myself I think BMW optimised the legacy engine design they were stuck with as best they could and what we have is basically as good as it gets. The only single hypothesis that fits the data there is, is that cars in warmer climes fail more often (as a function of number of cars sold)...how resilient that inference may be is another matter.