Official S65 Bearing Specification/Clearance Wiki

[whats77inaname]

Originally Posted by SenorFunkyPants

Further obfuscation and evasion noted.

Talk about the pot calling the kettle black *lol*

[SenorFunkyPants]

Originally Posted by regular guy

This thread is about clearance and bearing wear due to lack of clearance. Too little clearance is determined by the ratio (there's that word again) between journal diamter and clearance.

Yeah I think you will find that clearance is just clearance. There is no ratio inferred or defined when using the word clearance (its typically defined as: An intervening space or distance allowing free play, as between machine parts). Of course it may be defined as a function of a ratio which changes the meaning - a bit like effective compression ratio, the reader knows exactly what is meant but its up to him to decide if he has the intellectual honesty to admit it.

Originally Posted by regular guy

Whether it's aftermarket crank and rods doesn't matter because they follow the same factory specifications. As such, they were designed to have the same (too little) clearance as BMW and notably had the same fate.

Irrelevant I'm afraid...again an engine constructed using pattern parts predicts nothing about wear rates in oem parts especially at this level of tolerances.

Originally Posted by regular guy

Do you ever plan to circle any spots you see detonation on those pistons? What's next? Now that you're locked in to an explanation of the previous piston pictures, the new piston pictures should make your head spin trying to explain without contradicting what you said yesterday. I truly can't wait to see what comes next.

Leaving the childish sarcasm aside.
As I said earlier on piston deposits "I'm no expert by any stretch of the imagination" so I read it as I understand it.
But it was a good ruse putting up the first array of piston crown photos for comments then later saying you can't read anything from the pictures as the car was started up and stopped twice a day for 75 days.

[SenorFunkyPants]

One of the cornerstones of the tight bearing theory is the supposed poor reliability of the rod bearings in the M5s S85 motor (same engine architecture as the S65).
You would think that with these much older motors with higher mileage there would be a high engine failure rate due to rod bearing failures.
Yet a thread in M5board from a couple of months ago "S85 engine failure registry" has just five entries. 4 from the USA and one from SA (4 of the engines had some sort of tune.)
Even taking into account that there are only about 1/3 the number of S85s compared to S65s it is still a very low number of failures (relatively).
I was speaking today with the M Power master tech at my UK dealer about the S85 and while he listed all the problems he sees with this engine (vanos, oil pump and smg) he said he hadn't seen or heard of any engine bearing failures in the S85 or S65. Not that it proves anything but it was interesting.

[jcolley]

Originally Posted by SenorFunkyPants

One of the cornerstones of the tight bearing theory is the supposed poor reliability of the rod bearings in the M5s S85 motor (same engine architecture as the S65).
You would think that with these much older motors with higher mileage there would be a high engine failure rate due to rod bearing failures.
Yet a thread in M5board from a couple of months ago "S85 engine failure registry" has just five entries. 4 from the USA and one from SA (4 of the engines had some sort of tune.)
Even taking into account that there are only about 1/3 the number of S85s compared to S65s it is still a very low number of failures (relatively).
I was speaking today with the M Power master tech at my UK dealer about the S85 and while he listed all the problems he sees with this engine (vanos, oil pump and smg) he said he hadn't seen or heard of any engine bearing failures in the S85 or S65. Not that it proves anything but it was interesting.

Please tell me the extent of your research to refute a point is not a thread that I started a couple of months ago. Oddly, since I have no financial interest in ensuring the data is complete or a bone to pick with someone on the internet I haven't put much effort into compiling 8 years of data in other posts.


*Google "thrown rod site:http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/"

*Google "blown engine site:http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/"

*Google "engine replacement site:http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/"

If you're using incomplete data as evidence to your counterpoint to an argument, I hope you have nothing to do with statistical analysis for a living. Presenting such as that to support your argument is the equivalent of partisan media coverage of political issues in the US. You can do better than that...

I also spoke with a BMW M "master technician" a couple of weeks ago. Things we discussed:

* S85 rod bearing issues- stated he had seen none. Then again, hasn't seen a rod bearing cap removed from an engine since he went through the training program. He had seen thrown rods and holes in oil pans, but they don't take them apart, they just charge for a new engine.

* Injector failures- Ensured me that replacing a stuck open injector was the only corrective action necessary after hydrolocking the engine. I'm not even touching this one.

* Running lighter oil- Empatically stated that the VANOS system would cease functioning entirely due to the [extremely high flow rate[/B] in the VANOS system. The guy clearly has zero understanding of hydraulic pistons and solenoid operated, spool type, multi-way, proportional hydraulic control valves.

* Throttle actuator failures- He was certain based on testing they had done that all the failures were electronic in nature. Evidence would indicate otherwise.

* SMG errata- Stated that remaining clutch life can be read by diagnostics and that Launch Control usage is recorded by time and date. I can refute both of those having dumped the entire SMG_60.prg file in the most recent ISTA (Rheingold) distribution to see every function call available. Neither exist with the exception of a soltary counter called "race starts (Anzahl Rennstarts)" which contains no datestamping.

Perhaps there is a different training program in the UK, but that title alone imparts absolutely zero credibility IMO.
Everyone seems to indicate opinion, theory, supposition, and counterpoint, but I have seen very little independant effort put in to collection and sharing of data supporting their view aside from the OP and a couple of others.

[jcolley]

Originally Posted by SenorFunkyPants

Sorry I've only just got round to reading that link (past the first page).
I speed read (so I may have missed some detail) the thread and I have to admit to thinking the German OP is a bit sketchy. Pictures of an S85 engine stood on a wooden pallet and on bricks in a farm shed is not inspiring confidence. The rate that he asserts he is repairing S85/65s would indicate several hundreds (or even thousands) of failures worldwide. And of course it should be noted that his "friend" who is fixing 2 engines a week apparently works for BMW and it can be assumed that the engines he is receiving are those returned to BMW on an exchange basis for units replaced in the field (worldwide). That as well would indicate 100 S85 engines being replaced every year.
Does that fit with what you know?...because when I keyworld search for S85 engine failures, apart from this guy I don't find very many at all.
Of the engines failures that you can be absolutely certain of, do you have an idea of how many come from outside the USA?

While Duschanio may not have a glamorous shop to photograph, it's pretty hard to argue with the photos he's shown over the last couple of years. His English is not very strong, but I've had a few conversations with him and gather that he is an independant mechanic and his "M engineer" friend assists him on the side.

As I mentioned in the above post, if you want to find them, don't use S85 in the google search, but constrain the search within the E60 section of M5board as I showed above. Not many of those running around without S85s. I would say that there are many members there from outside the US given the former owner of the forum was not from the US and at least at one point there was a much larger ratio of Non-Us to US members. Or perhaps effective ratio...I'm not sure anymore.

I am trying to get more members to populate the registry, but many were long gone from the forum before the idea came about.

Without a doubt, many early failures of these engines were due to the VANOS High pressure pump failing, resulting in the redesign of the drive teeth to a larger profile to support the tooth loading of the helical gears (another indicator BMW M engineers aren't always right the first time). An unfortunate "feature" of th S85 is that the VANOS HP pump is gear driven and then the main oil pump chain driven from that. This means that when a non-fatal casualty occurs with the VANOS HP Pump, it usually caused a fatal casualty by taking out the prime mover for the Main Oil pump. If they had only incorporated the Main oil pump drive sprocket on the front of the crankshaft instead of the HP pump, we would likely have seen far fewer catastrophic engine failures with the S85.

However, search there for thrown rods and see what you find. Oddly, I can't get on there from work, only on here.

[SenorFunkyPants]

Originally Posted by jcolley

Please tell me the extent of your research to refute a point is not a thread that I started a couple of months ago. Oddly, since I have no financial interest in ensuring the data is complete or a bone to pick with someone on the internet I haven't put much effort into compiling 8 years of data in other posts.

The fragility of S85 rod bearings has reached urban myth proportions. Yet simple searches don't give nearly enough failures. I have joined M5board to see if that helped and I still can't find the rash of engine failures that the engines bad reputation suggests. Of course there are no doubt failures that I haven't come across...but it does makes you wonder how much is some form of internet Chinese whispers.
And it seems to be replaying with S65 engines...the whole well scripted presentation alerting everyone to this massive BMW cockup which lucky for us has been found out, has created a form of blind hysteria among some owners. I honestly don't fully buy it, 57000 engines with this massive flaw has so far produced a mere 20 odd failures (and not all of these can be confirmed as bearing failure).

[SenorFunkyPants]

Originally Posted by jcolley

While Duschanio may not have a glamorous shop to photograph, it's pretty hard to argue with the photos he's shown over the last couple of years. His English is not very strong, but I've had a few conversations with him and gather that he is an independant mechanic and his "M engineer" friend assists him on the side.

I've read the thread and it all seems too odd to be believable.
Showing engines in a farm outhouse on bricks surrounded by sand/sawdust and dirt, I wouldn't let anyone who works in those conditions anywhere near my engine. Yet claims he is fixing S85/65 engines every other week.
How many engines would have to be failing in Germany for one guy based on a farm to be repairing at such a rate?
Documented repairs done at BMW indy repair shop or maybe a well known tuner is one thing but this guy? Smells way too much of fish for my liking.

[BobS]

Originally Posted by SenorFunkyPants

The fragility of S85 rod bearings has reached urban myth proportions. Yet simple searches don't give nearly enough failures, I have tried all combinations of keywords to try and find the level of failures to match expectations and can't. I have joined M5board to see if that helped and I still can't find the rash of engine failures that the engines bad reputation suggests. Of course there are no doubt failures that I haven't come across...but it does makes you wonder how much is some form of internet Chinese whispers.
And it seems to be replaying with S65 engines...the whole well scripted presentation alerting everyone to this massive BMW cockup which lucky for us has been found out, has created a form of blind hysteria among some owners. I honestly don't fully buy it, 57000 engines with this massive flaw has so far produced a mere 20 odd failures (and not all of these can be confirmed as bearing failure).

I agree, you also have people with over 100,000 miles and still running fine....

[jcolley]

My engine was running fine as well. Most of them do until they dont. I changed mine since I was already in there inspecting for cylinder scoring.

Who was it that posted those pics of used rod bearings a few pages back that weren't significantly worn? Oh wait, that's right...there aren't any.

I'm sure it's all a conspiracy and we've gone to great lengths to plant these previously worn bearings into perfectly healthy engines. You people and your tin-foil hats...

Either that or 100% of the microscopic percentage of bearings examined in all production S85 and S65 engines just happen to look bad. I suppose it's possible a perfectly healthy set of bearings will pop in here any day now. I'll wait patiently while I'm breaking in my engine again.

Found a forum member in the UK with a spun rod bearing. Will post a link when I'm not on mobile.

[jcolley]

A few minutes of searching over there yields a few more:

http://www.m5board.com/vbulletin/e60...lp-advice.html

Here's the UK failure:
http://www.m5board.com/vbulletin/e60...hese-v10s.html

http://www.m5board.com/vbulletin/e60...wn-engine.html

http://www.m5board.com/vbulletin/e60...ml#post1782187

http://www.m5board.com/vbulletin/e60...se-advice.html

http://www.m5board.com/vbulletin/e60...ml#post2270701

as well as the registry I was trying to start:

http://www.m5board.com/vbulletin/e60...-registry.html

Again, I'll be the first to state that not all were strictly bearing failures without cause. So I don't know that it's the "cornerstone" of the theory for the S65, the S85 certainly has its additional complexity to thank for some of those failures.

But to assume that BMW engineers (or any for that matter) never make mistakes or apply enough margin for error in the design fails to explain the VANOS pump redesign (insufficient tooth profile) or VANOS line failures or any other number of recalls and design changes.

Take it as you will, most engines will probably last well over 100k. Just as the S62 cars are now well understood with their "unique problems", the S85 is now coming of that age, and the S65 will in a couple of more years.

Anyway, enough of

More data please.

[kawasaki00]

Originally Posted by jcolley

Anyway, enough of

More data please.

There is more on the way, taking delivery of a set of pistons rods and bearings tomorrow. We will put a lot to rest with the data.

[BMRLVR]

Originally Posted by kawasaki00

There is more on the way, taking delivery of a set of pistons rods and bearings tomorrow. We will put a lot to rest with the data.

Can't wait to see the data!

[swamp2]

Originally Posted by jcolley

A few minutes of searching over there yields a few more:
...
as well as the registry I was trying to start:

How about a very simple statistic here on the S85. What is the total failed engines reported divided by total production volume? Obviously, not all failures arrive on the internet and also not all reported failures will be attributable to a potential bearing issue. It is important to know if this is a 0.1% problem, 1% or 10%. Again, just order of magnitude.

Originally Posted by jcolley

Who was it that posted those pics of used rod bearings a few pages back that weren't significantly worn? Oh wait, that's right...there aren't any.

Does this really prove much of anything? It might show (assuming a large wealth of other data exists showing many models of cars with 10's of thousands of miles on each specimen, where bottom ends from engines showing no outward abnormal signs have been disassembled and their bearing show essentially no wear) that S65 bearings wear faster than those engines bearings. I've repeatedly asked for some reasonable estimates of the remaining lifespans (heck even a rough guess) of all of these bearings pulled from perfectly functioning engines. Is the number 1k mi, 5k mi, 10k mi, 50k mi, 100k mi, etc. I've even tried to find some sort of estimate for the longevity of such bearings in a typical production passenger vehicle. No disguising my ignorance on these particular queries...

Heck, I'm probably going out on a limb here but maybe, just maybe the bearings in the S65 will wear somewhat quickly initially and then "settle in" to a period of greatly decelerated wear. Purely speculative here, who knows.

Originally Posted by jcolley

But to assume that BMW engineers (or any for that matter) never make mistakes or apply enough margin for error in the design fails to explain the VANOS pump redesign (insufficient tooth profile) or VANOS line failures or any other number of recalls and design changes.

I don't think most of us that assume BMW have not just completely cocked up such an absolutely critical engine parameter believe BMW are in any way immune from either engineering or manufacturing failures. However, at the same time to also purport that any given known design/engineering "failure" means any other one is more or less likely is a bit absurd.

Getting pretty well OT but can you actually claim or demonstrate that the S85 VANOS issue was a large scale and clear engineering/design screw up? Isn't the proof of such a claim really in the pudding (i.e. only if a recall occurs)?

[catpat8000]

Originally Posted by jcolley

My engine was running fine as well. Most of them do until they dont. I changed mine since I was already in there inspecting for cylinder scoring.

Who was it that posted those pics of used rod bearings a few pages back that weren't significantly worn? Oh wait, that's right...there aren't any.

I'm sure it's all a conspiracy and we've gone to great lengths to plant these previously worn bearings into perfectly healthy engines. You people and your tin-foil hats...

Why are you being so hostile? People are legitimately asking where all the S65 failures are. That's all. It's a reasonable question: the S65 con rod bearings are such a big problem, so where are all the failures?

We all have S65 engines and none of us want them to blow. We are all trying to analyze different angles but as soon as someone challenges the conventional wisdom, there's a tiny minority who have mini temper tantrums. Do you guys not understand that this is how knowledge advances? By questioning the status quo? If nobody ever questioned anything, we'd all still think the sun goes around the earth and we sure as heck wouldn't be posting messages on a computer bulletin board because there wouldn't be any computers.

It really makes me wonder how many folks on this list would prefer there to be a large scale problem just so they could be "right".

[regular guy]

Bearing Eccentricity (part-1):

The inside bearing surface is not round. It has a lemon shape due to the varying thickness of the bearing wall having maximal value at the centerline (T) and gradually decreasing towards the parting line. It is accepted to measure the minimal value of the bearing wall thickness (Te) at a certain specified height h in order to exclude the zone of the crush relief.

The difference between the maximal and minimal wall thickness is called eccentricity:

eccentricity = T - Te

Recommended values of eccentricity:

For passenger cars: 0.0002 - 0.0008” For high performance cars: 0.0006 - 0.0012”

Dr. Dmitri Kopeliovich: Geometrical parameters of engine bearings

How to measure:

First we need to calibrate our measuring equipment. Each measurement will be taken three times to ensure consistency. Measurements will be taken approximately 1/4" above the parting, and another measurement taken 1/4" below the parting line. I'm not sure if this is the correct location to take this measurement, but I did note the measurement at the actual parting line (or as close as I could measure) did not change by any significant amount (~0.00005 - 0.00010).

The bearings measured are not new. These were the bearings that were used in the 2008 with 30000 mile engine. This is the engine whose spark plugs, pistons, and bearing photos were posted recently. It's unclear how much the used condition of these bearings will affect the measurements. We know for certain it won't make them smaller, but we don't know for certain how much it will make them larger (if any). Later this week, Kawasaki00 will measure the same connecting rods with new bearings to get more accurate measurements. He also intends to measure bearing crush, and I hope connecting rod bore diameter (variance) as well.



The results:

Click on any of the photos to see exploded views.

Cylinder	1	2	3	4
1/4" Above
90-degree
1/4" Below
Extra Clearance	0.00100	0.00130	0.00170	0.00125
1/4" Above	2.04910	2.04930	2.04960	2.04945
90-degree	2.04810	2.04800	2.04790	2.04820
1/4" Below	2.04940	2.04930	2.04940	2.04940
Extra Clearance	0.00130	0.00130	0.00150	0.00120
	1	2	3	4
	5	6	7	8
Extra Clearance	0.00110	0.00160	0.00120	0.00090
1/4" Above	2.04900	2.04940	2.04900	2.04880
90-degree	2.04790	2.04780	2.04780	2.04790
1/4" Below	2.04940	2.04940	2.04940	2.04885
Extra Clearance	0.00150	0.00160	0.00160	0.00950
1/4" Above
90-degree
1/4" Below
Cylinder	5	6	7	8

Conclusions:

Minimum eccentricity: 0.00090"
Maximum eccentricity: 0.00170"
Expected results: 0.00060" - 0.00012"
# Within recommendation: 6
# Outside recommendation: 10

As measured we can certainly see some bearing eccentricity. According to the article quoted above, the expected results should range between 0.00060" - 0.00120" for high performance cars. For the most part, especially given the used nature of these bearings, these results seem within range, or not very far outside of it. In the next few days, we should be able to post part-2 of this article: eccentricity measurements on the same connecting rods with new bearings measured properly and with more accurate equipment. Once those measurements are taken, they will be added to the front page article of official clearance measurements.

[regular guy]

Originally Posted by catpat8000

Why are you being so hostile? People are legitimately asking where all the S65 failures are. That's all. It's a reasonable question: the S65 con rod bearings are such a big problem, so where are all the failures?

We all have S65 engines and none of us want them to blow. We are all trying to analyze different angles but as soon as someone challenges the conventional wisdom, there's a tiny minority who have mini temper tantrums. Do you guys not understand that this is how knowledge advances? By questioning the status quo? If nobody ever questioned anything, we'd all still think the sun goes around the earth and we sure as heck wouldn't be posting messages on a computer bulletin board because there wouldn't be any computers.

It really makes me wonder how many folks on this list would prefer there to be a large scale problem just so they could be "right".

Pat, the number of cars that will blow motors will be small. That's always been my theory. It should be sub 1% in fact it should be sub 0.5%. Can I tell you how long until one blows? No, I don't think anybody can. I will accept your criticism to make sure that good data is produced for good reasons, and not just to be right.

[catpat8000]

Originally Posted by regular guy

Bearing Eccentricity (part-1):

The difference between the maximal and minimal wall thickness is called eccentricity:

eccentricity = T - Te

Recommended values of eccentricity:

For passenger cars: 0.0002 - 0.0008” For high performance cars: 0.0006 - 0.0012”

Dr. Dmitri Kopeliovich: Geometrical parameters of engine bearings

I'm not competent to comment on your photos or on bearing eccentricity but I did want to say that seems like an informative and useful link on bearings! Thanks for posting.

Pat

[regular guy]

Originally Posted by catpat8000

I'm not competent to comment on your photos or on bearing eccentricity but I did want to say that seems like an informative and useful link on bearings! Thanks for posting.

Pat

Thanks. I think the original credit goes to Yellow Snow however. I believe he first posted links to this series of articles.

[SenorFunkyPants]

So here it is...SFP theory V1.

Firstly I think you can tell a lot from what changes BMW made to the S65 design compared to the S85 and what they didn’t change.
First and foremost they didn’t change the bearing clearance. A call to Mahle Clevite and it was done – it would have been a minimal cost and it is simply inconceivable that if BMW had a shed load of failed S85 engines due to bearing clearance they would not have made that call. I understand that a rod bearing materials change was made around 2010/11 - if true this would have been yet another opportunity that they didn't take to make a legitimate change to the bearing clearance as part of the (forced by legislation?) revision. They did however spend a crap load of money and time changing the Vanos, the lubrication system and the ionic current anti knock system.

The wear mechanism:
Despite the fact that minimum bearing clearance is at 6 o’clock (bottom bearing shell) and 12 o’clock (top bearing shell), the principle wear points occur at about 11 o’clock or 1 o’clock on the top bear shell only (position depending on which side of the V the piston is from).
It is therefore apparent that the wear is initiated by excessive downward force (created by the combustion process) during the combustion stroke. As the rod (and consequently the top bearing shell) is forced downwards against the crankshaft journal the oil film between the parts tends to be squeezed out. During optimum working conditions it would be expected that the oil film would remain intact with no abnormal wear occurring.
However as peak combustion pressures increase (for example during supercharging) the downward force passes a threshold where the oil film becomes increasingly compromised and the wear rate rises. It is of course not inconceivable that a tight rod bearing clearance makes the environment more vulnerable to increased levels of force.

Here is a graph to illustrate (makes it look more scientific!)




So what factors can affect the wear mechanism.

Oil Temperature
For most owners it is the key factor. Low oil temperature will see the graph curve move significantly to the left.

Supercharging.
This obviously significantly increases peak combustion pressures and increased rod bearing wear should be expected and indeed occurs.

Tuning.
ECU tunes that involve advancing the ignition may have unintended consequences on the functionality of the ionic current anti knock system and may allow an increased amount of detonation.

Fuel octane and the ionic current anti knock system.
There was a major upgrade of the system from the S85 to the S65 engines, which should give a clue as to its importance to the safe running of the engine. There seems to be little data on the system apart from the principles on how it works. The recommended fuel is 93 Aki and the minimum required is 91 Aki. Owners who have data logged their M3s report that with 91Aki fuel the ionic current system is constantly pulling the timing to counter detonation. A key question, would you expect a car running constantly at the edge of detonation to put more load on the rod bearing environment than the same car running normally on 93 Aki all else being equal? I don't know, what is certain though is that as octane levels fall so will the ability of the ionic current anti knock system to efficiently control detonation as the combustion event becomes more chaotic. One tank of 87 octane alone could be sufficient to cause significant accelerated wear on the rod bearings with no other impact other than to be present when the engine is opened up at some time in the future.

© Pants industries.

[aussiem3]

Originally Posted by SenorFunkyPants

So here it is...SFP theory V1.

Firstly I think you can tell a lot from what changes BMW made to the S65 design compared to the S85 and what they didn’t change.
First and foremost they didn’t change the bearing clearance. A call to Mahle Clevite and it was done – it would have been a minimal cost and it is simply inconceivable that if BMW had a shed load of failed S85 engines due to bearing clearance they would not have made that call. I understand that a rod bearing materials change was made around 2010/11 - if true this would have been yet another opportunity that they didn't take to make a legitimate change to the bearing clearance as part of the (forced by legislation?) upgrade. They did however spend a crap load of money and time changing the Vanos, the lubrication system and the ionic current anti knock software.

The wear mechanism:
Despite the fact that minimum bearing clearance is at 6 o’clock (bottom bearing shell) and 12 o’clock (top bearing shell), the principle wear points occur at about 11 o’clock or 1 o’clock on the top bear shell only (position depending on which side of the V the piston is from).
It is therefore apparent that the wear is initiated by excessive downward force (created by the combustion process) during the combustion stroke. As the rod (and consequently the top bearing shell) is forced downwards against the crankshaft journal the oil film between the parts tends to be squeezed out. During optimum working conditions it would be expected that the oil film would remain intact with no abnormal wear occurring.
However as peak combustion pressures increase (for example during supercharging) the downward force passes a threshold where the oil film becomes increasingly compromised and the wear rate rises. It is of course not inconceivable that a tight rod bearing clearance makes the environment more vulnerable to increased levels of force.

Here is a graph to illustrate (makes it look more scientific!)

So what factors can affect the wear mechanism.

Oil Temperature
For most owners it is the key factor. Low oil temperature will see the graph curve move significantly to the left.

Supercharging.
This obviously significantly increases peak combustion pressures and increased rod bearing wear should be expected and indeed occurs.

Tuning.
ECU tunes that involve advancing the ignition may have unintended consequences on the functionality of the ionic current anti knock software and may allow an increased amount of detonation.

The ionic current anti knock system.
There was a major upgrade of the system from the S85 to the S65 engines, which should give a clue as to its importance to the safe running of the engine. There seems to be little data on the system apart from the principles on how it works. The recommended fuel is 93 Aki and the minimum required is 91 Aki. Owners who have data logged their M3s report that with 91Aki fuel the ionic current system is constantly pulling the timing to counter detonation. Now it gets a bit fuzzy, if the engine spends more time running at the edge of (or with mild) detonation what is the impact on peak combustion pressure? Would you expect a car running constantly at the edge of detonation to put more load on the rod bearing environment than the same car running 93 Aki all else being equal? Anyway what is certain is that as octane levels fall so will the ability of the ionic current anti knock system to efficiently control detonation as the combustion event becomes more chaotic. One tank of 87 octane could be sufficient to compromise the rod bearings.


Comments and critique from open minded posters welcome.
Childish nonsense from intellectually dishonest numbskulls...not so much.

I reserve the right to change my mind and post edit to make myself look smarter! © Pants industries.

This thread is really growing legs and don't know where we'll end up. Page 49 already ... but guess what, it is teaching me the inner workings of engines and especially the /// ones. Thank you to all.

[SenorFunkyPants]

Originally Posted by jcolley

My engine was running fine as well. Most of them do until they dont. I changed mine since I was already in there inspecting for cylinder scoring.

Who was it that posted those pics of used rod bearings a few pages back that weren't significantly worn? Oh wait, that's right...there aren't any.

I'm sure it's all a conspiracy and we've gone to great lengths to plant these previously worn bearings into perfectly healthy engines. You people and your tin-foil hats...

Originally Posted by catpat8000

Why are you being so hostile? People are legitimately asking where all the S65 failures are. That's all. It's a reasonable question: the S65 con rod bearings are such a big problem, so where are all the failures?

We all have S65 engines and none of us want them to blow. We are all trying to analyze different angles but as soon as someone challenges the conventional wisdom, there's a tiny minority who have mini temper tantrums. Do you guys not understand that this is how knowledge advances? By questioning the status quo? If nobody ever questioned anything, we'd all still think the sun goes around the earth and we sure as heck wouldn't be posting messages on a computer bulletin board because there wouldn't be any computers.

It really makes me wonder how many folks on this list would prefer there to be a large scale problem just so they could be "right".

Could not have said it better myself.

[jcolley]

Originally Posted by catpat8000

Why are you being so hostile? People are legitimately asking where all the S65 failures are. That's all. It's a reasonable question: the S65 con rod bearings are such a big problem, so where are all the failures?

We all have S65 engines and none of us want them to blow. We are all trying to analyze different angles but as soon as someone challenges the conventional wisdom, there's a tiny minority who have mini temper tantrums. Do you guys not understand that this is how knowledge advances? By questioning the status quo? If nobody ever questioned anything, we'd all still think the sun goes around the earth and we sure as heck wouldn't be posting messages on a computer bulletin board because there wouldn't be any computers.

It really makes me wonder how many folks on this list would prefer there to be a large scale problem just so they could be "right".

If I am coming across as hostile, my apologies, it certainly is not intended to be and I couldn't agree more that the theory should be scrutinized to ensure the accuracy of what is being presented. My frustation plays out in the manner in which these potential issues are discovered and the lack of any acknowledgement by the manufacturer or effort to improve. What makes these cars different is the emotion and passion from the enthusiasts who own them. I have to believe that the engineers at ///M have every bit of the same and it's hard to come to terms that in the end, willfully or not, they are bound by the rules of business and maintaining corporate image and profit margin. If these cars were marketed purely at die-hard enthusiasts, they could embrace subjects like this, work collaboratively with their consumers, and bolster their own reputation and sales doing so. But they're not; they market the cars with enough performance to hold our attention, but still civil enough to produce large enough numbers for mass consumption of much, much larger target audience. More than likely, corporate acknowledgement of this, or any other for that matter, potential problem with a product would damage either current sales or stock value. So until it reaches a point where not dealing with a problem becomes more expensive than dealing with it, the casual consumers and die-hards are equally let down. The difference is, the casual consumers will move on and those who really love and embraced the platform are left to figure out how to prolong it. It's really a rant against an inevitable thing, so I'll keep my tone in check better.

I'll be the first one to line up in the "obsessed with the engine" group for the S85. I don't know for certain why some decisions were made which potentially reduce the life span of it as a whole. My background is in a field where absolutely zero defects are acceptable and cost is not one of the factors in determining if something should be fixed or redesigned because a component failure could lead to the redefinition of a "catasrophic event". While I understand how some things could have been done better with these engines, I have no concept of the financial growth in doing so.

Specific to this issue though, it just seems like it would truly have been a no-cost issue to rectify.

Originally Posted by swamp2

How about a very simple statistic here on the S85. What is the total failed engines reported divided by total production volume? Obviously, not all failures arrive on the internet and also not all reported failures will be attributable to a potential bearing issue. It is important to know if this is a 0.1% problem, 1% or 10%. Again, just order of magnitude.

That was the point of starting the S85 failure registry. We have great data on total numbers produced, but little energy going into the figuring out the numerator. As mentioned by someone else, someone has the data already, but we'll never see it.

Originally Posted by swamp2

Does this really prove much of anything? It might show (assuming a large wealth of other data exists showing many models of cars with 10's of thousands of miles on each specimen, where bottom ends from engines showing no outward abnormal signs have been disassembled and their bearing show essentially no wear) that S65 bearings wear faster than those engines bearings. I've repeatedly asked for some reasonable estimates of the remaining lifespans (heck even a rough guess) of all of these bearings pulled from perfectly functioning engines. Is the number 1k mi, 5k mi, 10k mi, 50k mi, 100k mi, etc. I've even tried to find some sort of estimate for the longevity of such bearings in a typical production passenger vehicle. No disguising my ignorance on these particular queries...

Heck, I'm probably going out on a limb here but maybe, just maybe the bearings in the S65 will wear somewhat quickly initially and then "settle in" to a period of greatly decelerated wear. Purely speculative here, who knows.

I think the only thing it really proves is that owning that car with higher mileage (let's say over 50k miles), you most likely have bearing wear and it's a subject to be aware of. I may have stated it poorly, but that's really all I was trying to convey. While obviously some engines will happily go on another 50-150k miles, some may only go on another 5k. Do we have conclusive evidence that 10W-60 caused this? No. Do we have conclusive evidence that low octane fuel caused it? No. Can we take action to try and mitigate the wear? Sure, run lighter oil and never less than 93 octane (US). Do we know if that will work? Nope. Not for another 30-50k miles or so. I do personally feel that the clearance/oil weight has much more weight than octane based on virtually everyone running TWS and virtually no one claiming to run low octane.

Originally Posted by swamp2

I don't think most of us that assume BMW have not just completely cocked up such an absolutely critical engine parameter believe BMW are in any way immune from either engineering or manufacturing failures. However, at the same time to also purport that any given known design/engineering "failure" means any other one is more or less likely is a bit absurd.

Getting pretty well OT but can you actually claim or demonstrate that the S85 VANOS issue was a large scale and clear engineering/design screw up? Isn't the proof of such a claim really in the pudding (i.e. only if a recall occurs)?

These engines and cars are remarkably complex and well engineered machines. There are literally millions of things they got right and as with any product, a few they could have improved on. I agree that a discovery of an engineering problem doesn't make another more likely and was not the intent, but certainly should dissuade an individual from seeing them as infallible and incapable of error.

Searching the forums for early production S85 failures, many problems show. While that is not a hard statistic, it does indicate the surfacing of a potential problem. BMW issued SI B 11 10 05 for cars in production up to 11/22/05 which addressed one problem with the high pressure discharge line. 1 month later they redesigned the helical drive gear for the VANOS high pressure pump and the crankshaft mounted helical gear which drives it to incorporate a taller tooth profile. The mechanics I have spoken with over the years about the pumps have all agreed they see fewer failures on the VANOS pumps with the redesigned drive.

I don't know that I would consider those things conclusive proof, but certainly clear indicators BMW felt a problem existed and took action to correct it. Many engines (my own 11/05 build included) ran without issues for years. The pump never became a recall because the total failure costs never exceeded the projected recall campaign cost. I personally would not consider a recall as the definitive proof for that reason. While there are many BMW dealership technicians who know nothing of rod bearing problems, there are very few who have experience with the S85 that haven't seen VANOS problems. You S65 guys really got a much more simple and apparently reliable system.

Again, apologies if coming across as hostile, it was not the intent. There's enough drama in this thread already, I'll just go back to reading and learning.