Official S65 Rod Bearing Condition Example Thread

[Scharbag]

Originally Posted by 23

2011 E92 DCT 76500KM
cyl 8 looks really bad.

Jesus. Those have strange wear. Good job on changing them.

[Fezza]

but why is yours showing copper? they were changed to aluminium from 2010 onwards. or were they not stock to begin with?

[Bartledoo]

Originally Posted by Fezza

but why is yours showing copper? they were changed to aluminium from 2010 onwards. or were they not stock to begin with?

The switch occurred somewhere around May 2010 build dates iirc, so some 2011 models still had copper/lead bearings.

[tdott]

Originally Posted by Fezza

but why is yours showing copper? they were changed to aluminium from 2010 onwards. or were they not stock to begin with?

According to RealOEM, build date from 06/01/2010 had the newer style bearings. But in practice some probably already have engines built prior from the shelf that went in.

[kevin @ eas]

Just replaced with BE bearings. Car is a 2011 with 31k miles.

[330ciprem]

Originally Posted by kevin @ eas

Just replaced with BE bearings. Car is a 2011 with 31k miles.

Are those scoring marks on the bearings?

[Helmsman]

Originally Posted by 330ciprem

Are those scoring marks on the bearings?

Thought the same, plenty debris living high life in the oil?

[kevin @ eas]

Originally Posted by 330ciprem

Are those scoring marks on the bearings?

It is scoring marks and you could feel it with your fingernail. The crank was perfect though so no damage.

[Scharbag]

Originally Posted by kevin @ eas

It is scoring marks and you could feel it with your fingernail. The crank was perfect though so no damage.

Seems like a lot of scoring. Wonder why so pronounced on this engine. Any thoughts?

Thanks for sharing!

[tom @ eas]

Originally Posted by Scharbag

Seems like a lot of scoring. Wonder why so pronounced on this engine. Any thoughts?

Thanks for sharing!

Definitely a head-scratcher at only 31K. Good thing the owner jumped on replacement sooner rather than later.

[deansbimmer]

Originally Posted by tom @ eas

Definitely a head-scratcher at only 31K. Good thing the owner jumped on replacement sooner rather than later.

Another good example for low mile owners who poo-poo the need to service their bearings.

[Scharbag]

Originally Posted by deansbimmer

Another good example for low mile owners who poo-poo the need to service their bearings.

Exactly - it is just a statistical problem. No amount of maintenance or proper warm up will mask the problem of bearings that are so tight that oil flow is compromised. Especially at high RPM.

[abdulbata]

Just got my rod bearings replaced at 71k miles
2012 e92 m3 6 speed
Replaced with Clevite Calico CT-1 Coated Extra Clearance Rod Bearing Set and ARP bolts

[cchen9_]

29K, 2013 DCT

[Helmsman]

Originally Posted by cauQazn

29K, 2013 DCT

Strange punch in the center of the top ones, eaten through a layer or just the way the pic came out? (top or bottom shells?).

[cchen9_]

Originally Posted by Helmsman

Strange punch in the center of the top ones, eaten through a layer or just the way the pic came out? (top or bottom shells?).

Unfortunately the shop did not designate top vs bottom but did pair and label the baggies they gave me. 1->8.
Not sure if the wear is normal I posted on fb some people said it looks normal and I could've got 30K more out of them and then some thought it was abnormal...
I wanted to get them out of the way anyway. Just happened to be in town and the shop had everything ready to go and turned it around in 2 days. VAC + ARP bolts were put in.

[Helmsman]

Originally Posted by cauQazn

Unfortunately the shop did not designate top vs bottom but did pair and label the baggies they gave me. 1->8.
Not sure if the wear is normal I posted on fb some people said it looks normal and I could've got 30K more out of them and then some thought it was abnormal...
I wanted to get them out of the way anyway. Just happened to be in town and the shop had everything ready to go and turned it around in 2 days. VAC + ARP bolts were put in.

Anyways I think good to have the motor secured. VAC/ARP should provide plenty nice miles to come.

[kevin @ eas]

Just did this one today, replaced at 93k.

[cchen9_]

Originally Posted by Helmsman

Anyways I think good to have the motor secured. VAC/ARP should provide plenty nice miles to come.

My thoughts as well.

[Scharbag]

I know these are not from an S65 and that the N54 does not rev to 8400RPM, but it still runs to 7000RPM and puts out ~100HP/L.

I just wanted to show these bearings as this is what rod bearings should look like coming out of an engine. These are not perfect, but WAY better than pretty much any set of S65 bearings posted on this site. They also match Clevite's normal wear pattern (last photo).

I borrowed these photos from an N54 forum. Engine likely had long OCIs and has 85,000 miles on the clock.

Cheers,

[IamFODI]

Not at all disagreeing that those are what used rod bearings "should" look like.

That said, if we're going to make comparisons with other engines to imagine a world in which S65 rod bearings come out looking like this, don't we need a ton more context? Rod bearing dimensions, rod and piston package weight, rod/stroke ratio, etc.?


This is emphatically not my area of expertise, but I did some quick Googling and some back-of-the-envelope math on what I understand to be relevant factors. Interested if anyone can check me on any of this, or throw in some other relevant info:

1. I found 1074.4 g for the N54's rods, pistons, bolts, and bearings (forum won't let me post the link but it's easily found). For the S65 I got 1104.7 g, and I'm not sure if that includes bearings or bolts.

2. Mean piston speeds are ~5% higher for the S65 if these calculations are right. That suggests the S65 has a much milder rod/stroke ratio, but not enough to fully offset the difference made by RPM.

3. I'm seeing big end widths in the ballpark of 18 - 18.5 mm for the S65 and 20 - 21 mm for the N54. Taking rod bearing journal diameters from BE's Wiki, and using pi * diam * width to get a rough estimate of rod bearing area, I'm getting slightly lower numbers for the S65 than for the N54 (just under vs. just over 3500 mm^2), with the percentage difference depending on how much narrower each engine's rod bearing is than its big end bore. That obviously can't be used as a basis for exact comparison because the numbers are rough, but it does strongly suggest that the S65 is using the same or less bearing area per cylinder. It does have 33% more cylinders, but it's also making around 33% more power, so power-per-cylinder should be comparable, leaving RPM-related forces as the main variables.


Again, this is NOT my area of expertise, but while those differences each look small in isolation, I can easily imagine the effects compounding pretty significantly. If the S65 is generating higher piston speeds with heavier internals, all with less bearing area.... Doesn't it make sense that the S65 is harder on its rod bearings?


And of course there are other potential curveballs in the designs of the rods, which determine where the greatest forces are seen. This article is kind of comparing extremes, but it shows how differences in rod shape, dimensions, and materials, combined with differences in rod/stroke ratios and piston speeds, can load different parts of the rod very differently. That doesn't say anything definite, but it does show that there's a lot going on besides all the stuff we've mentioned so far, and it suggests that the real answer might be a lot more obscure and complicated than people like us can grok.

[Scharbag]

Originally Posted by IamFODI

Not at all disagreeing that those are what used rod bearings "should" look like.

That said, if we're going to make comparisons with other engines to imagine a world in which S65 rod bearings come out looking like this, don't we need a ton more context? Rod bearing dimensions, rod and piston package weight, rod/stroke ratio, etc.?


This is emphatically not my area of expertise, but I did some quick Googling and some back-of-the-envelope math on what I understand to be relevant factors. Interested if anyone can check me on any of this, or throw in some other relevant info:

1. I found 1074.4 g for the N54's rods, pistons, bolts, and bearings (forum won't let me post the link but it's easily found). For the S65 I got 1104.7 g, and I'm not sure if that includes bearings or bolts.

2. Mean piston speeds are ~5% higher for the S65 if these calculations are right. That suggests the S65 has a much milder rod/stroke ratio, but not enough to fully offset the difference made by RPM.

3. I'm seeing big end dimensions in the ballpark of 18 - 18.5 mm for the S65 and 20 - 21 mm for the N54. Taking rod bearing journal diameters from BE's Wiki, and using pi * diam * width to get a rough estimate of rod bearing area, I'm getting slightly lower numbers for the S65 than for the N54 (just under vs. just over 3500 mm^2), with the percentage difference depending on how much narrower each engine's rod bearing is than its big end bore. That obviously can't be used as a basis for exact comparison because the numbers are rough, but it does strongly suggest that the S65 is using the same or less bearing area per cylinder. It does have 33% more cylinders, but it's also making around 33% more power, so power-per-cylinder should be comparable, leaving RPM-related forces as the main variables.


Again, this is NOT my area of expertise, but while those differences each look small in isolation, I can easily imagine the effects compounding pretty significantly. If the S65 is generating higher piston speeds with heavier internals, all with less bearing area.... Doesn't it make sense that the S65 is harder on its rod bearings?


And of course there are other potential curveballs in the designs of the rods, which determine where the greatest forces are seen. This article is kind of comparing extremes, but it shows how differences in rod shape, dimensions, and materials, combined with differences in rod/stroke ratios and piston speeds, can load different parts of the rod very differently. That doesn't say anything definite, but it does show that there's a lot going on besides all the stuff we've mentioned so far, and it suggests that the real answer might be a lot more obscure and complicated than people like us can grok.

For sure, apples to apples would be a better comparison. It is just really hard to find photos of GOOD bearings as most people post photos of BAD bearings.

As for all of the variables it all boils down to 1 thing: a properly designed hydrodynamic bearing IS NOT A WEAR ITEM in passenger cars. Even in race engines, the bottom end is not designed to wear. Sure, some race teams in uber competitive classes will minimize clearances and run minimal oil flow to reduce parasitic losses in the engine. This will reduce useful life as there is no safety margins at all.
Also, race engines live at full throttle all-the-time. But that is not how engines are designed for road use. And think, the average M3 spends what percentage of its life at WOT? What percentage of its life above 6000RPM? Typically, on the streets, WOT has limited applications.

What would be great is if we had photos of good bearings from 5.2L Audi V10s, 2.0L Honda F20c, Porsche GT3 and Ferrari F136 engines as they are high revving, high HP examples to say the least. I would bet real money that those factory bearings typically look just like Clevite/King/ACL intended.

The ONLY time bearings do not look like they should is due to a problem. Period. To properly beat the dead horse: at no time should anyone accept the notion that rod and/or main bearings are wear items in a passenger car.

Cheers,