Official S65 Rod Bearing Condition Example Thread

[----Flyin-High----]

Originally Posted by tdott

The Ad lines up with what Deansbimmer suspected:
Maintenance items within last 2k miles:
WPC Coated OEM Bearings w/ OEM Bolts

Looks like it was well taken care of then, I wouldn't worry about it too much. Enjoy it.

those were the previous bearings in the photo, the new ones installed were WPC coated. Am I misunderstanding something?

[deansbimmer]

Originally Posted by ----Flyin-High----

those were the previous bearings in the photo, the new ones installed were WPC coated. Am I misunderstanding something?

Perhaps, or we are misunderstanding since your first post had minimal information.

That was Roman's car. Great guy. He was not the first owner either, didn't have it for too long I don't think. So to clarify, you posted pics that roman provided you of the bearings he replaced- you did not replace bearings again under your ownership?

I'd bet a free rod bearing job that those bearings didn't have 80k miles on them. Either way, you got a fantastic car and a great engine in that thing, so enjoy!

[Helmsman]

Originally Posted by deansbimmer

Fine? No. Typical of the poor wearing S65 bearings we see most? Yes.

The engine from the last picture has to have a full teardown and rebuild now.
Definitely not good.

Sure I can see they (first 3 sets) are touched, but what's your judgement on actual wear on them? First layer off? Dimensions affected?

[----Flyin-High----]

Originally Posted by deansbimmer

Perhaps, or we are misunderstanding since your first post had minimal information.

That was Roman's car. Great guy. He was not the first owner either, didn't have it for too long I don't think. So to clarify, you posted pics that roman provided you of the bearings he replaced- you did not replace bearings again under your ownership?

I'd bet a free rod bearing job that those bearings didn't have 80k miles on them. Either way, you got a fantastic car and a great engine in that thing, so enjoy!

Yes correct, sorry no intention to be vague. Just putting the inormation I had out there. Really felt lucky to find the car in this shape, roman seems like good dude too.

Thanks for replying, good to know the car has solid bones and came from a good home. Im not as worried installing the ESS 625 at 90k.

[IamFODI]

Serious question about the LCI rod bearings: Given that they don't have different-looking layers as lead/copper bearings do, how do they get discolored?

In my admittedly little experience trying to educate myself, I haven't seen aluminum alloy bearings in other applications show this kind of discoloration, even when they're clearly worn. Is there any available info on what the discoloration means from a chemical or metallurgical standpoint?

[Scharbag]

Originally Posted by deansbimmer

Fine? No. Typical of the poor wearing S65 bearings we see most? Yes.

The engine from the last picture has to have a full teardown and rebuild now.
Definitely not good.

Curious as to the damage found in the last engine if any. Was the crank still ok? Was the tear down required just to make sure there was no metal in the VANOS system etc.? Also, do you know the history of the bad engine - such as OCI and typical use case?

That last set of bearings are what nightmares are made of...

Thank you again for sharing with the community.

Cheers,

[OneWhite35]

Just got my bearings done at RMP Motors in Toronto Canada. Replaced with VAC coated bearings with ARP bolts.

Below are the original OEM bearings on my 2008 M3 6MT. The car has ~77,500km and was supercharged since 2009.

(1 through 8 from left to right; lower bearings in the top row and upper bearings in the bottom row.)

[Kelse92]

Originally Posted by mgmarsh39

MY 13 with 21k miles. Super glad I had this done.

Saw your car in person on Friday when I dropped my car off for some other service. Beautiful low-mile example! And really interesting to see the wear compared to the mileage here, most with your miles don’t think they need them

[deansbimmer]

Originally Posted by IamFODI

Serious question about the LCI rod bearings: Given that they don't have different-looking layers as lead/copper bearings do, how do they get discolored?

In my admittedly little experience trying to educate myself, I haven't seen aluminum alloy bearings in other applications show this kind of discoloration, even when they're clearly worn. Is there any available info on what the discoloration means from a chemical or metallurgical standpoint?

Actually, the bearings DO still have different looking layers. The only difference is the material and therefore, the color of each layer. There's no real discoloration occuring. The color change you see is literally each layer being worn away and exposing the next layer which is a different metal and color. Traditionally, bearings would not wear past their babbit layer (in this example a tin alloy, so you would never see any discoloration. (black specs in the bearing is debris being embedded in the softest top layer- a function of the babbit layer which is lost as it wears away)

Contrary to popular belief, bearings do not create a perfectly round bore.
Since these layers are being worn off, dimensions that the engineers designed into the bearings are changing which affect the hydrodynamic bearing's ability to maintain support of the assembly, which in turn allows an increasing amount of contact between the journal and bearing, which speeds up the wear process until the bearing fails altogether.

The crank from the last pic is not OK. It has some hot spots and some metal transfer but I believe we can save it with a light polish without damaging its surface hardness or roundness. Between this and the metal that would be distributed throughout the engine, the only way to ensure a reliable outcome is to disassemble and rebuild.

[IamFODI]

Originally Posted by deansbimmer

Actually, the bearings DO still have different looking layers. The only difference is the material and therefore, the color of each layer. There's no real discoloration occuring. The color change you see is literally each layer being worn away and exposing the next layer which is a different metal and color. Traditionally, bearings would not wear past their babbit layer (in this example a tin alloy, so you would never see any discoloration. (black specs in the bearing is debris being embedded in the softest top layer- a function of the babbit layer which is lost as it wears away)

First time I'm hearing this. Everything I've read on Al/Sn bearings says that the Al/Sn sliding layer is as thick as the Pb and Cu layers in a trimetal bearing combined because it essentially replaces both of them, and the only thing underneath it is a very thin bonding layer of Al and then the steel backing. I've also never seen that Al/Sn bearings have babbit layers.

If the Al/Sn part were worn through, wouldn't that mean instant catastrophe? And what part of that has a darker/browner color than Al/Sn?

Or, are these bearings made differently? If so, I suspect the bearing wiki needs to be updated, and I'd love to read more.

[Helmsman]

Originally Posted by IamFODI

First time I'm hearing this. Everything I've read on Al/Sn bearings says that the Al/Sn sliding layer is as thick as the Pb and Cu layers in a trimetal bearing combined because it essentially replaces both of them, and the only thing underneath it is a very thin bonding layer of Al and then the steel backing. I've also never seen that Al/Sn bearings have babbit layers.

If the Al/Sn part were worn through, wouldn't that mean instant catastrophe? And what part of that has a darker/browner color than Al/Sn?

Or, are these bearings made differently? If so, I suspect the bearing wiki needs to be updated, and I'd love to read more.

Interested too. I'll grab one of my used LCI (702/703) shells and do some experiment scraping when I get time...

[deansbimmer]

Originally Posted by IamFODI

First time I'm hearing this. Everything I've read on Al/Sn bearings says that the Al/Sn sliding layer is as thick as the Pb and Cu layers in a trimetal bearing combined because it essentially replaces both of them, and the only thing underneath it is a very thin bonding layer of Al and then the steel backing. I've also never seen that Al/Sn bearings have babbit layers.

If the Al/Sn part were worn through, wouldn't that mean instant catastrophe? And what part of that has a darker/browner color than Al/Sn?

I'm using the word Babbit loosely to define a soft top surface layer of a plain bearing, it may also be defined as an overlay (like some may say Coke and mean soda)...

From wikepedia:
"The original Babbitt alloy was invented in 1839 by Isaac Babbitt[1] in Taunton, Massachusetts, United States. He disclosed one of his alloy recipes but kept others as trade secrets.[2] Other formulations were developed later.[3] Like other terms whose eponymous origin is long since deemphasized (such as diesel engine or eustachian tube), the term babbitt metal is frequently styled in lowercase.[3][4] It is preferred over the term "white metal", because the latter term may refer to various bearing alloys, lead- or tin-based alloys, or zinc die-casting metal"


The 702/703 Glyco bearings still have a (thin) overlay, lining, and steel backing (shell). 702/703 bearings have an intermediate layer of some type of copper alloy as seen in the below closeup of a 702/703 bearing I attached for illustration. The copper may be mixed with tin or aluminum. We don't know for sure.

I'm not aware of any publication outlining the exact alloy or composition of these BMW bearings, hence the lack of discussion and education on the subject. There are dozens and dozens of ways manufacturers compose bearings. There is so much more to identify beyond simply bi-metal or tri-metal composition. That might be like identifying diesel and gasoline engines and saying every engine in each category is the same. There's a lot more to define. Here are some helpful links:

https://en.wikipedia.org/wiki/Babbitt_(alloy)

http://www.kingbearings.com/material-type/lead-free/

As with any plain bearing, once the overlay is worn through and no longer able to embed debris and help lubricate the journal in the absence of oil, accelerated wear to the crankshaft journal will be observed. At some point when the oil wedge is no longer operating at peak efficiency (due to deterioration of the bearing bore shape), and the lining has enough physical contact with the journal, the bearing will gall and ultimately seize.

[IamFODI]

If that's the case, then this isn't a traditional bimetal aluminum bearing as BE's wiki says. It's something else.

Also, if that intermediate layer does indeed include copper, that might make it easier to track wear on these bearings with oil analysis.

[deansbimmer]

Originally Posted by IamFODI

Also, if that intermediate layer does indeed include copper, that might make it easier to track wear on these bearings with oil analysis.

If you ever go to look at the oil analysis thread, you'll notice plenty of 702/703 cars showing copper in the oil... Alum is too common elsewhere in the engine to isolate how much is from bearing wear. The valve guides are copper/zinc alloy which muddies the water. Lead, being as soft as it is, traditionally shoots up just before bearing failure, making it easier to spot trouble since its the only lead inside the engine.

[Helmsman]

Originally Posted by deansbimmer

I'm using the word Babbit loosely to define a soft top surface layer of a plain bearing, it may also be defined as an overlay (like some may say Coke and mean soda)...

From wikepedia:
"The original Babbitt alloy was invented in 1839 by Isaac Babbitt[1] in Taunton, Massachusetts, United States. He disclosed one of his alloy recipes but kept others as trade secrets.[2] Other formulations were developed later.[3] Like other terms whose eponymous origin is long since deemphasized (such as diesel engine or eustachian tube), the term babbitt metal is frequently styled in lowercase.[3][4] It is preferred over the term "white metal", because the latter term may refer to various bearing alloys, lead- or tin-based alloys, or zinc die-casting metal"


The 702/703 Glyco bearings still have a (thin) overlay, lining, and steel backing (shell). 702/703 bearings have an intermediate layer of some type of copper alloy as seen in the below closeup of a 702/703 bearing I attached for illustration. The copper may be mixed with tin or aluminum. We don't know for sure.

I'm not aware of any publication outlining the exact alloy or composition of these BMW bearings, hence the lack of discussion and education on the subject. There are dozens and dozens of ways manufacturers compose bearings. There is so much more to identify beyond simply bi-metal or tri-metal composition. That might be like identifying diesel and gasoline engines and saying every engine in each category is the same. There's a lot more to define. Here are some helpful links:

https://en.wikipedia.org/wiki/Babbitt_(alloy)

http://www.kingbearings.com/material-type/lead-free/

As with any plain bearing, once the overlay is worn through and no longer able to embed debris and help lubricate the journal in the absence of oil, accelerated wear to the crankshaft journal will be observed. At some point when the oil wedge is no longer operating at peak efficiency (due to deterioration of the bearing bore shape), and the lining has enough physical contact with the journal, the bearing will gall and ultimately seize.

Thanks Deansbimmer, good input.

[Scharbag]

Originally Posted by IamFODI

If that's the case, then this isn't a traditional bimetal aluminum bearing as BE's wiki says. It's something else.

Also, if that intermediate layer does indeed include copper, that might make it easier to track wear on these bearings with oil analysis.

If you ever get to the copper on an Al/Sn bearing, it was effed a long time ago.

[Scharbag]

Saw these on Facebook with the post saying:

"Rod bearings and motor mounts were completed today. Not terrible.
65k miles on my 2011."

Thought I would share them here. If the original owner is on here, apologies for jumping the gun if you were going to post here too. But damn, these bearings are toast. "Not terrible..."

Cheers,

[tom @ eas]

MY10 M6, 70K miles. Had a rough life:

[wfdeacon88]

Originally Posted by tom @ eas

MY10 M6, 70K miles. Had a rough life:

Look kinda similar to mine (2009 @ 96k)

[tom @ eas]

MY09 M3 @ 105K miles. Almost a carbon copy of the previous M6.

[Blindside_137]

Yikes

[Macpsi]

bearings from my 2011 with 112k miles.