BMW NA Approves New S65 Engine Replacement Due to Bad Rod Bearings

I have been around these forums a very long time. I can assure you that not everybody that says that they did it by the book actually did it by the book. I am referring to engine break in and allowing the oil temperature to attain the optimal range before going WOT + redline.

Having said that, I do think parts such as rod bearings can fail. I think they will fail more often when the driver / owner disregard recommended best practices by the manufacturer.

We will never know how many rod bearings' failure were due to flawed parts nor how many failures were the result of driver decisions.

Mine has 61k on the odometer and I cannot remember ever having wondered whether bearings would fail on my next road trip.

The whole RB thing, to me, is pointless. If one has a rod bearings concern, drive something else. If it isn't a concern enjoy the BMW model that has the ultimate naturally aspirated engine.

Cheers :D

Eau Rouge wrote

I have been around these forums a very long time. I can assure you that not everybody that says that they did it by the book actually did it by the book. I am referring to engine break in and allowing the oil temperature to attain the optimal range before going WOT + redline.

Having said that, I do think parts such as rod bearings can fail. I think they will fail more often when the driver / owner disregard recommended best practices by the manufacturer.

We will never know how many rod bearings' failure were due to flawed parts nor how many failures were the result of driver decisions.

Mine has 61k on the odometer and I cannot remember ever having wondered whether bearings would fail on my next road trip.

The whole RB thing, to me, is pointless. If one has a rod bearings concern, drive something else. If it isn't a concern enjoy the BMW model that has the ultimate naturally aspirated engine.

Cheers :D

I second that motion

If only I knew the engine warm up and driving habits of the previous owner of my M3.

If I purchased my M3 new I probably wouldn't deal with replacement RBs.

Timujin wrote

If only I knew the engine warm up and driving habits of the previous owner of my M3.

If I purchased my M3 new I probably wouldn't deal with replacement RBs.

You probably still would have to deal with it, the bearing shells see wear everytime you start the motor and oil has to flow into the bearings.

amrazM wrote

You probably still would have to deal with it, the bearing shells see wear everytime you start the motor and oil has to flow into the bearings.

Not really - oil film is still there and when your car starts, it does so under no load conditions and at low RPM. Relative to the forces seen at 8400RPM, startup is not even worth talking about. EDIT: See below for further discussion on startup wear. The intent was not to mislead. Yes, "wear" does happen during startup...

Regardless of warmup etc., if your bearings are too tight, then you will need to replace them or risk spinning one of them.

Cheers,

Scharbag wrote

Not really - oil film is still there and when your car starts, it does so under no load conditions and at low RPM. Relative to the forces seen at 8400RPM, startup is not even worth talking about.

Regardless of warmup etc., if your bearings are too tight, then you will need to replace them or risk spinning one of them.

Cheers,

+1.

Timujin wrote

If only I knew the engine warm up and driving habits of the previous owner of my M3.

If I purchased my M3 new I probably wouldn't deal with replacement RBs.

My previous owner had zero modifications and a bicycle rack installed on the roof. Less than 6000 miles a year. Could be a good or bad thing:confused2

Scharbag wrote

Not really - oil film is still there and when your car starts, it does so under no load conditions and at low RPM. Relative to the forces seen at 8400RPM, startup is not even worth talking about.

Regardless of warmup etc., if your bearings are too tight, then you will need to replace them or risk spinning one of them.

No, it is a fact that in normally operating engines the most bearing wear occurs at startup. Wear is occurring to the bearings until oil pressure builds which produces the hydrodynamic bearing that the crankshaft rides on during operation. Under oil pressure this fluid bearing prevents the physical contact between bearings and journals.

In addition to every startup, engines with unfavorable tolerance stacking from the factory are hit with the double whammy. Its why we see "babied" engines fail just like those that are tracked. How the engine is treated only speaks to a portion of how the bearings will wear.

You can read about how engine bearings work here:
http://kingbearings.com/files/Engine_Bearings_and_How_They_Work.pdf

deansbimmer wrote

No, it is a fact that in normally operating engines the most bearing wear occurs at startup. Wear is occurring to the bearings until oil pressure builds which produces the hydrodynamic bearing that the crankshaft rides on during operation. Under oil pressure this fluid bearing prevents the physical contact between bearings and journals.

In addition to every startup, engines with unfavorable tolerance stacking from the factory are hit with the double whammy. Its why we see "babied" engines fail just like those that are tracked. How the engine is treated only speaks to a portion of how the bearings will wear.

You can read about how engine bearings work here:
http://kingbearings.com/files/Engine_Bearings_and_How_They_Work.pdf

For sure, hence the "not really" comment.

Yes, the majority of "wear" occurs at startup, because the hydrodynamic bearings are not yet operating under pressure. BUT, on a properly designed engine, that wear is soooooo minuscule that we might as well ignore it. If that were not the case, then my buddies 32 year old E30 city commuter would be a paperweight cause he starts that damn thing at least 10 times every day!!

Now, if you drive a cold engine hard right after startup, then that is a recipe for additional wear, and a good hard slap.

By no means am I disagreeing with you sir. You know far more about engines than I do. I do think it is important to clarify that the normal startup "wear" would never cause a rod bearing to look like some that have been pulled from S65 engines. The issue with the S65 is that under load, and at higher RPM, the rod bearings are NOT operating as a proper hydrodynamic bearings.

Cheers,

Scharbag wrote

I do think it is important to clarify that the normal startup "wear" would never cause a rod bearing to look like some that have been pulled from S65 engines. The issue with the S65 is that under load, and at higher RPM, the rod bearings are NOT operating as a proper hydrodynamic bearings.

This is key and why I felt your last post could have been misleading to some readers. If you're considering that startup accounts for some .00001% of an engine's run time then it could be said that it is not worth considering.

The fluid bearing in stock S65's is inadequate indeed compared to an M20, but factually the most wear per revolution does still occur during startup. Carry on.

deansbimmer wrote

This is key and why I felt your last post could have been misleading to some readers. If you're considering that startup accounts for some .00001% of an engine's run time then it could be said that it is not worth considering.

The fluid bearing in stock S65's is inadequate indeed compared to an M20, but factually the most wear per revolution does still occur during startup. Carry on.

I have an 08 with 64000 miles and will likely get the bearings done around 75-100k, most likely at your shop. Im the farthest thing from a mechanic but a lot of times I see reference to start/stop cycles when talking about bearing wear which is consistent with your statement. That said, do the OEM bearings remain inferior once the car is at operating temperature? A lot of us are red light Mario Andrettis, I can't imagine that type of driving and associated loads can be good for any rod bearing...am I correct?

InnerBlueSkies wrote

That said, do the OEM bearings remain inferior once the car is at operating temperature?

Yes. Inadequate OEM clearances remain inadequate regardless of engine temperature. Extra clearance bearings like BE bring the dimensions back to the industry suggested .001" per journal inch.

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

kiquos wrote

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

Who did the work? Do you have pictures of the bearing they replaced to see if they had any signs of imminent failure or perhaps signs that there may have already been damage that could effect the crank?

Either the rod bearing job was not done right or you already had other issues, like main bearing wear. Given that the failure was a day after the rod bearings were installed, I’d guess the failure was due to the rod bearing job. Could be the bearings were not installed right or the car was not put back together right. Either way, major bummer given that you had just didn’t money to help maintain the car.

Hopefully, the undersized ACL bearings that appear, based on the description, to be added clearance, were not installed by mistake. Deansbimmer write a list a few days ago explaining the ACL bearing options.

kiquos wrote

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

Sell me ur Dinan pulley Lool

kiquos wrote

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

These are the posts that scare me and put me off of having the RBs changed. I've seen a handful of stories like this where the motor locks up shortly after swapping in new bearings. Seems like it's a gamble either way with this motor; roll the dice and don't have them done or roll the dice and hope the shop is competent enough to do the job right. If it was indeed the shop's negligence that caused the failure, I sure hope they stand by it and step up. Best of luck OP.

850tgul wrote

kiquos wrote

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

These are the posts that scare me and put me off of having the RBs changed. I've seen a handful of stories like this where the motor locks up shortly after swapping in new bearings. Seems like it's a gamble either way with this motor; roll the dice and don't have them done or roll the dice and hope the shop is competent enough to do the job right. If it was indeed the shop's negligence that caused the failure, I sure hope they stand by it and step up. Best of luck OP.

That's like the argument anti-vaxers use.

The majority of rod bearing changes are done properly and work just fine. And I would argue that there has never been proof of a main bearing failure being caused by a properly installed rod bearing change.

Cheers,

850tgul wrote

kiquos wrote

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

These are the posts that scare me and put me off of having the RBs changed. I've seen a handful of stories like this where the motor locks up shortly after swapping in new bearings. Seems like it's a gamble either way with this motor; roll the dice and don't have them done or roll the dice and hope the shop is competent enough to do the job right. If it was indeed the shop's negligence that caused the failure, I sure hope they stand by it and step up. Best of luck OP.

You could buy a new car tomorrow that bricks its engine by the end of the day. You roll the dice no matter what.

kiquos wrote

Reviving the thread.
I bought an 2011 M3 with 80k miles and had the brgs replaced, it failed the next day at the track, hole on the side of the block.
New bearings ACL w/ 0.0025" clearance and Carrillo rod bolts.
waiting to take engine apart to see the issue? Parts or Labor.
I was told there is no break in period by the bearing manufacturer.

I've seen clearances from .001", 0.0025", and 0.050". What is supposed to be the correct clearance?

Ever so sorry to hear mate. Industrial "standard" clearance in S65 type application is 0.0025, plenty to read about this subject on the board. ACL is certainly one of multiple proven supplier for the S65 (have a set inside myself since 1.5y).
This doesn't sound like a rod bearing issue as such but rather install, still might be a good thing if you posted here as well: https://www.m3post.com/forums/showthread.php?t=786615

Curious to hear about further findings. Good luck!

Scharbag wrote

That's like the argument anti-vaxers use.

The majority of rod bearing changes are done properly and work just fine. And I would argue that there has never been proof of a main bearing failure being caused by a properly installed rod bearing change.

Cheers,

I get it. If I keep my car long term, I will likely have them changed out as I believe the better bet is to have them swapped by the most competent shop you can find.
My point was only that the anxiety remains, even after dropping $3k to alleviate the anxiety. You spend the $ and then have to hope the shop did the install correctly. Would still be in the back of my mind when I drove the car.

850tgul wrote

I get it. If I keep my car long term, I will likely have them changed out as I believe the better bet is to have them swapped by the most competent shop you can find.
My point was only that the anxiety remains, even after dropping $3k to alleviate the anxiety. You spend the $ and then have to hope the shop did the install correctly. Would still be in the back of my mind when I drove the car.

Have there been other (multiple) examples of individuals changing their RBs and then experiencing a related failure?

I do think their is credence to your opinion above and tend to agree to some extent.

Regardless, this is not a cut and dry issue with the s65 and the type of RB, installation process, etc. all play a factor it would appear.

We still don't know why some s65s are still running strong on 150-200k miles and some failed sub 50k. It's too bad BMW has never weighed in on the matter to assist their M enthusiasts.