Official S65 Rod Bearing Condition Example Thread

[serranot]

Originally Posted by Sneaky Pete

AIUI
The ~doubling of oil flow measured, is essentially all flowing through the extra clearance rod bearings....as the oil will always take the path of least resistance.
As long as the oil pump remains capable of presenting oil to the main bearings at the same oil pressure (before and after the RB change) then the flow through them should remain unchanged.

There is only one path--mains -> rods. If oil flow through the rods is increased, then it's coming from the mains. Can't have one without the other.

[Sneaky Pete]

Originally Posted by serranot

There is only one path--mains -> rods. If oil flow through the rods is increased, then it's coming from the mains. Can't have one without the other.

I get how you are understanding the principle, but I'm not sure its totally correct.

From a paper on Oil Flow Simulation.
"The [main] bearings have a open track in the centre that goes partly or all around its circumference. At the main bearing, the oil will enter the tracks through the supply hole and lubricate the bearing. The rest will enter the crankshaft leading to con-rod journal through the channels. From here it will lubricate and supply oil to the connecting rod."

So as the pressurised oil enters the Main bearing it has a choice, exit the Main bearing sideways and be returned to the sump or continue through the crankshaft and onto the Rod bearings.
Myself I can't see any reason why the oil flow sideways through the Main bearings and back to the sump should increase. In that environment, nothing has changed...the oil pressure hasn't changed (hopefully) and neither has the Main bearing clearance.
However the pathway towards the (extra clearance) Rod bearings is now less restricted and the oil flow can and will increase along that route.
At least that is my understanding.

[Scharbag]

Originally Posted by serranot

There is only one path--mains -> rods. If oil flow through the rods is increased, then it's coming from the mains. Can't have one without the other.

I disagree that it is that simple. Here is my take on this (electrical engineer waxing about mechanical stuff - yikes):

The oil enters the main bearings from the main oil gallery. From there, it has 2 paths of flow.

The first is across the main bearing surface. This is the actual oil that squishes out the sides of the main bearings and forms the oil wedge that lubricates the main journals and keeps the crank happy as a clam.

The second is through the oil galleries drilled through the crank to the rod journals. Once the oil gets to the rod journal, it squishes out the sides providing the rod bearing oil wedge (if clearances allow for adequate squishyness).

The S65 rod galleries are in the middle of the main journal, just like most other engines. The rod gallery lines up with the groove in the center of the main bearing shell. So while the increased flow will pass "through" the main bearing, the oil flow across the main bearing surface should remain unaffected if available oil pressure remains the same.

In this regard, SneakyPete is correct. Technically, one would expect the flow across the main bearing surface will be reduced slightly. This is due to the 3%-4% drop in available oil pressure after changing to BE rod bearings. The drop in pressure is due to increased flow losses upstream of the crank (more flow in same pipe causes greater flow losses).

I hope that the main bearings are not so sensitive that the small drop in flow will cause them an issue. The variance in oil pump from car to car might be higher than 4% from factory. I will glady accept this slight reduction in main flow in order to increase the rod bearing flow.

And here is a nice PDF from Mahle that shows the bearing failure modes.

I am by no means an expert on engines. If I am wrong, please let me know.

Cheers,

[Ngilbe36]

For the visual learners, here is a very simplified explanation of the general system at play.

[Helmsman]

Originally Posted by Ngilbe36

For the visual learners, here is a very simplified explanation of the general system at play.

An even better one I think. Yeah, yeah, don't mean to bore the experts but for the guys on the same level as me.

[serranot]

Originally Posted by Scharbag

I disagree that it is that simple. Here is my take on this (electrical engineer waxing about mechanical stuff - yikes):

The oil enters the main bearings from the main oil gallery. From there, it has 2 paths of flow.

The first is across the main bearing surface. This is the actual oil that squishes out the sides of the main bearings and forms the oil wedge that lubricates the main journals and keeps the crank happy as a clam.

The second is through the oil galleries drilled through the crank to the rod journals. Once the oil gets to the rod journal, it squishes out the sides providing the rod bearing oil wedge (if clearances allow for adequate squishyness).

The S65 rod galleries are in the middle of the main journal, just like most other engines. The rod gallery lines up with the groove in the center of the main bearing shell. So while the increased flow will pass "through" the main bearing, the oil flow across the main bearing surface should remain unaffected if available oil pressure remains the same.

In this regard, SneakyPete is correct. Technically, one would expect the flow across the main bearing surface will be reduced slightly. This is due to the 3%-4% drop in available oil pressure after changing to BE rod bearings. The drop in pressure is due to increased flow losses upstream of the crank (more flow in same pipe causes greater flow losses).

I hope that the main bearings are not so sensitive that the small drop in flow will cause them an issue. The variance in oil pump from car to car might be higher than 4% from factory. I will glady accept this slight reduction in main flow in order to increase the rod bearing flow.

And here is a nice PDF from Mahle that shows the bearing failure modes.

I am by no means an expert on engines. If I am wrong, please let me know.

Cheers,

Thanks to all for the explanations. Very helpful.

[admranger]

300k rod bearing in the video looked like it had less wear (other than the pitting) than most S65 rod bearings...

[Solo_M_Tech]

Something that everyone has forgotten about increased oil flow is the added cooling benefits. Reduced bearing and journal surface temperatures will also decrease wear and fatigue of the components.

Oil isn't only a lubricant....

[Scharbag]

Originally Posted by ham_sammich

Something that everyone has forgotten about increased oil flow is the added cooling benefits. Reduced bearing and journal surface temperatures will also decrease wear and fatigue of the components.

Oil isn't only a lubricant....

Very true!

[Green-Eggs]

Originally Posted by Helmsman

An even better one I think. Yeah, yeah, don't mean to bore the experts but for the guys on the same level as me.

The very first point in this video is something Pete doesn't understand and needs to learn. I watched the video specifically to see if that subject would come up. Glad to see it was the very first topic mentioned.

Originally Posted by ham_sammich

Something that everyone has forgotten about increased oil flow is the added cooling benefits. Reduced bearing and journal surface temperatures will also decrease wear and fatigue of the components.

Oil isn't only a lubricant....

It's been mentioned a few times, but always good to mention again.

[Sneaky Pete]

The very first point in this video is something Pete doesn't understand and needs to learn.

I knew I wouldn't be able to bask for long in the afterglow of reading the immortal words "Sneaky Pete is correct" (post #465).
And true to form, along comes one of the usual suspects with a typical ad hominem.
Anything to steady the gravy train.

Oh and the idea that increased oil flow would improve bearing cooling...pah well that is just witchcraft!! lolz

[doogee]

Originally Posted by admranger

300k rod bearing in the video looked like it had less wear (other than the pitting) than most S65 rod bearings...

Yep. This forum has definitely brainwashed a lot of users into thinking that wear on these bearings is "normal".

[rymerc]

Originally Posted by doogee

Yep. This forum has definitely brainwashed a lot of users into thinking that wear on these bearings is "normal".

Every time I see someone post their s65 bearings I'll comment on how terrible they are. I apologize I can't catch every single one.

I've pulled apart 200k, 300k+ motors some of which were badly abused- driven with broken valve springs, burned valves, badly sludged oil, barely readable oil pressure, and rod bearings looked new.

In my limited personal experience I have not seen a motor with rod bearings as consistently laughable as these S65 motors.

[spazzyfry123]

I'll play. Car is still in the shop (getting some other things done while it's there), but they sent me a picture of the bearings. Glad I didn't roll the dice on this one and went ahead and took care of it. Hate that I need to resize the picture; it's made it look like there is "cross-hatching" that is not evident on the original picture. I'll grab some different pictures once I pick the car up and add these "trophies" to my collection.
As a side note, I am not sure which side is the top cap and the bottom. I didn't check my E-mail until after my shop had closed for the day.

2011 (8/11 build) E90 M3 6MT
Bearings shown below have ~63k miles on them.
Car was a pampered, low annual mileage baby before me.
Always held true to the "don't drive over 3k RPM before oil temps reach 200 with moderate throttle pressure" rule.
Oil changes every 5k.

You get the picture. Proof is that even the "most pampered" examples are suspect to heavily increased bearing wear. Quite excessive wear and what looks to be some "dirt" embedded into the bearings. Blackstone reports always show that I've got me a healthy one, so I'm interested to see the contaminant "dirt" markings in them; maybe a couple spots here and there, but this looks to be a lot!

Also it may be difficult to tell in the picture, but it would appear that there is linear scoring (the direction that the rod is turning within the bearing). Is this normal? Obviously the bearings are toast, but I'd like to get an idea of the health of the rest of the motor based on what I can see here, too.

These are being replaced with the BE bearings that arrived early this week.

[///M Power-Belgium]

Originally Posted by spazzyfry123

I'll play. Car is still in the shop (getting some other things done while it's there), but they sent me a picture of the bearings. Glad I didn't roll the dice on this one and went ahead and took care of it. Hate that I need to resize the picture; it's made it look like there is "cross-hatching" that is not evident on the original picture. I'll grab some different pictures once I pick the car up and add these "trophies" to my collection.
As a side note, I am not sure which side is the top cap and the bottom. I didn't check my E-mail until after my shop had closed for the day.

2011 (8/11 build) E90 M3 6MT
Bearings shown below have ~63k miles on them.
Car was a pampered, low annual mileage baby before me.
Always held true to the "don't drive over 3k RPM before oil temps reach 200 with moderate throttle pressure" rule.
Oil changes every 5k.

You get the picture. Proof is that even the "most pampered" examples are suspect to heavily increased bearing wear. Quite excessive wear and what looks to be some "dirt" embedded into the bearings. Blackstone reports always show that I've got me a healthy one, so I'm interested to see the contaminant "dirt" markings in them; maybe a couple spots here and there, but this looks to be a lot!

Also it may be difficult to tell in the picture, but it would appear that there is linear scoring (the direction that the rod is turning within the bearing). Is this normal? Obviously the bearings are toast, but I'd like to get an idea of the health of the rest of the motor based on what I can see here, too.

These are being replaced with the BE bearings that arrived early this week.

Of course your bearings show wear . But for your 63K miles they look not bad .Because we/I saw worse on here ..

It's not only our S65 bearings , the bearings from the S85 M5/6 engines show also premature wear !

[spazzyfry123]

Originally Posted by ///M Power-Belgium

Of course your bearings show wear . But for your 63K miles they look not bad .Because we/I saw worse on here ..

It's not only our S65 bearings , the bearings from the S85 M5/6 engines show also premature wear !

Ouch! Would the copper in bearings "exaggerate" the wear appearance? Seeing that mine do not have copper, I'm curious if they would look worse if they did have copper.

What are your thoughts on the contaminants? That is my main concern if I'm honest. Those same contaminants will be experienced throughout, not just the rods.

[pbonsalb]

Your bearing are not nearly as gone as those S85 bearings. I think it’s harder to gauge the wear on the later aluminum bearings just by looking at pictures. Take one and sand it down to expose the layers.

[///M Power-Belgium]

Originally Posted by spazzyfry123

Ouch! Would the copper in bearings "exaggerate" the wear appearance? Seeing that mine do not have copper, I'm curious if they would look worse if they did have copper.

What are your thoughts on the contaminants? That is my main concern if I'm honest. Those same contaminants will be experienced throughout, not just the rods.

Yours don't show copper and you're fine in your situation
But through the copper is mostly too late by the copper shavings in the oil and oil filter and transform our S65/85 engines in a ticking time bomb , in no time !

On the other hand we/I saw S65's with +200K miles on it, and they still running strong today !
That's why I said often..It's actually a German lottery ....

=> http://www.agkits.com/bearing-failure-analysis.aspx

[notouching]

Got my bearings replaced today.
2012 E92 6MT, 41k miles on stock bearings:




Replaced with BE bearings and their ARP bolts.
To me they don't look too terrible.
Sorry for potato camera pictures.

[tubedreamer]

2008 e90 m3. 43170 mi

Always used tws 10w60 until the Bmw twin power turbo 10w60 came out, then switched to that for the last two oil changes.

Car was driven pretty gently by po and us as infrequent daily drivers. Always warmed up oil before getting on the throttle and we only rarely go past 5k. Most of the last 15k miles are highway commuting.

Blackstone from 7500 and 15000 mi ago showed 3 and 10 ppm lead. I’ll update with readings from the most recent blackstone.

Playskool1 changed my rb and bolts to BE.

Some of the edges have a bit of copper showing through on the corners although I don’t see it in this photo.

[pbonsalb]

My 08 bearings at 60k looked a lot like tubedreamer but I had copper showing at the parting lines and down the sides.

[L4ces]

Originally Posted by jcolley

I can answer the first one directly. I have had a couple of billet cranks made and waiting on an another now from the same crank shop that Dinan uses. In fact, one of the ones that I purchased from them initially was excess inventory from a Dinan production batch. Yes, those crank main journals are the same size as OEM and yes the rod journals are about .0005" smaller in diameter than OEM.

Originally Posted by jcolley

I can answer the first one directly. I have had a couple of billet cranks made and waiting on an another now from the same crank shop that Dinan uses. In fact, one of the ones that I purchased from them initially was excess inventory from a Dinan production batch. Yes, those crank main journals are the same size as OEM and yes the rod journals are about .0005" smaller in diameter than OEM.

These last two posts are quite interesting. Fresh thinking that makes sense and we are not focusing on it is shocking. I had the exact same question before seeing rantarM3 post his two questions. I'd like to hear more, after all, it seems like the bearing problem is solved on the Dinan but there are no claims of it.