New Rod Bearings at 92k miles (but old ones look great!)

[FogCityM3]

Changed my rod bearings at 92.5k miles (2011.5 E90 M3). The old stock rod bearings came out nearly pristine! A tiny bit of scoring on one (Cyl 3 I believe - 2nd cylinder from Right/Passenger side Rear per labeling). The bearings were some of the best that the technician has seen (has done over 100 of them) and most likely could have gone to 130k miles. I went to Carbahn Auto Works (now owned by Steve Dinan again post his return from Ford Racing) to perform the work. They recommended a replacement with BE bearings and stock bolts, given they’ve been satisfied with the wear characteristics in some of the race engines, but frankly, having seen what I’ve experienced, I would have no qualms in putting in the stock bearings with stock bolts so long as is done by skilled technician.

To summarize my driving habits, would say they are very aggressive (but only after certain warm up and other conditions are met, see below). Mike Benvo of BPM, when I had an issue re-uploading my tune due to my laptop blitzing out, did a freeze-frame snapshot of the ECU at about 78,000 miles. I hit redline (raised to 8,600 rpm through the tune) over 2,500+ times and had some overrevs, including an incident at the track where I was in the wrong gear had an over-rev at over 9,000 rpm. At the time, Mike mentioned to me this was one of the most aggressively driven M3s he’s seen when looking at FreezeFrame. Additionally, due to the fantastic weather in CA, for about 35-40 weekends per year I go on a pretty extensive drive in the twistys, which involve a lot of high-revving (6.5k-8.5k rpm) 2nd gear driving where both the oil and coolant temps reach levels similar to the track. I have about 25 track days with the car (which I stopped tracking a year ago, now is just the daily + twisty road driver now that I’ve moved to the GT350), about 22 of which were with the BPM tune, which I have run for 64k miles. Most of the miles were under the “Dev Tune” which includes cold start rev-limit protection (hard RPM limit to 4.5k rpm until oil reaches 172 degrees, then have full rpm range, which is much later than stock) and pulls back rpm limit earlier than the factory at high temps when the rpm is at/near redline for sustained period of time.

For those following my posts over the years, I have been pretty skeptical of the prevailing theory, which seems to be assembly/tolerance stack issues on already tight clearances; while this is certainly possible (among many other things which have been discussed ad nauseam) would seem like a glaring misstep by a company that is very engineering focused and assembled the S65 and S85 engines by hand. Other theories have focused on ethanol in fuel, improper driving habits (warm up and lugging the engine), an ionic knock control system that may not be capturing all detonation and pre-detonation, tuned and supercharged engines, and lower fuel octane.

Personally, I think the most plausible explanation lies in the S65 vs most other engines as the way to properly drive one is quite different from most out there. Also this engine needs to be very well maintained but if it is, it can be driven very hard. Being a high-revving motor with a high compression ratio that really needs 93 octane to run at its optimum, can be very sensitive to poor driving habits including improper warm-up and using too high a gear while accelerating (lugging the engine). Peak torque (and peak cylinder pressure) occurs fairly early (for the rev range) around 3,900 rpm, and even with the stock cold start rev limit you are given access to the entire rev range very early (normal operating temp for oil should be about 200 degrees) and if you are using too high a gear around/near the peak torque, when oil isn't completely warmed up, on a less then optimal octane (91) it is putting a lot of pressure on the cylinders and hence the bearings. Also with such tight tolerances, there is probably not enough room for error under these conditions.

On the other hand, I believe that various theses of reasons for bearing failure I believe have been largely debunked by my experience include: 1) 91 octane gas; 2) 10w-60 oil is too thick; 3) don’t use aftermarket air filters as they let in too much dust/silica; 4) hitting redline a lot is bad; 5) you shouldn’t track the car; 6) driving aggressively/hard results in premature wear; 7) flaws with the ionic knock control system including failure to detect pre-detonation; 8) Running a tune is dangerous (have full confidence in at least the BPM tune in being very safe and protective) 9) Don’t raise redline on the tune. This only leaves driving/maintenance habits or assembly error/tolerance stack at the factory as the two major potential causes under normal aspiration (I really don’t think clearances are an issue per se, IF you drive and maintain the car properly. Interestingly the bearing clearance on the GT350 that are similarly tight to the M3). Hopefully by describing my driving habits and maintenance regimen, you can also follow some of these recommendations to extend your bearing life. Note that I am the original owner, so I was in control of the car and its maintenance the entire time. If you bought your car used, doing rod bearings is highly recommended as you have no idea how the former owner (or lessor) drove or maintained it (especially considering this engine is so different from 98% of the engines out there).

My mods include:
Dinan Intake (with K&N air filter); ran the EAS/Macht Schnell intake for about a year prior to this.
Dinan underdrive pulley
BPM tune with cold start rev-limit protection and raised redline to 8,600. Been running this tune since 2013 and for 64,000 miles (and initially ran the ESS tune since 2012 for about 9k miles more so total miles tuned is over 73k miles).
BMW M performance aftermarket exhaust. Cat back only (I have stock cats).

As a testament to my aggressive driving style, I’ve had 1) differential bolt snap, had to get new diff; 2) new clutch and flywheel at 75k miles; 3) new transmission at 80k miles under warranty (synchros were worn) 4) brake master cylinder and slave replaced under warranty at 65k miles

However, these are the things that I have done in order to preserve the engine, all of which I think really helped to keep the bearings/engine in great shape:

1) Followed BMW break-in procedure to the letter.
2) On cold starts, I just drive off, but really wait until temps get to 190+ before any high-revving above 4k rpm. The cold-start rev limit protection of the BPM tune (to 4.5k rpm) really helps a lot with this. Due to it being a daily driver, my typical commute is 20-30 minutes, and use the M3 for very short 5-10 minute trips as well.
3) Absolutely NO engine lugging. Always use a lower gear when doing any kind of even moderate acceleration or going up a hill. I believe there was a reason why BMW disabled the Efficient Dynamics shift points for the M3 (which can only be turned on by coding) is that the recommended shift points, while good for fuel economy, are far too early and are at a points where the engine lugs a LOT, thereby putting the most pressure on the cylinders and engine components.
4) Use regular 91 octane gas for daily /weekend fun driving (mostly Chevron); All track days have been with 100 octane unleaded race gas.
5) 1 bottle of Chevron Techron every 5k miles
6) Oil change every 7k miles; have only used Castrol Edge and new BMW TwinPower all 10w-60 (and ran MOTUL 10w-60 for 7k miles). Added about +1qt oil every 5k miles.
7) New spark plugs every 15k miles.
8) Aftermarket air filter change every year
9) head gasket changed under warranty at 80k
10) Transmission/Diff fluid change every 30k miles
11) Coolant flush every 50k miles.

I only did one oil analysis (really only to test for silicates post aftermarket filter change).

(*did a pic in natural light as iPhone camera caught too much of shadows)



Attachment 1938236

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Attachment 1938238

[Seattle M3]

It would be interesting to do a study to see what country has the biggest failure rate, ie; does Germany have lower rate because their cars are driven hot and hard. My theory with high performance cars is exactly like you, maintain them to the t, but drive them like they are intended. The engineers didn’t design this car to lug around in traffic. In all my E90 M3’s - 4 in total I have over 100kmiles, most of which have been run hot and hard. I have never had any mechanical issues! Maybe just dumb luck but I don’t think so....

[kimiraikkonen]

Interesting post and think there are some merits that you bring up for sure.

Not trying to start another MT vs. DCT type of discussion, but when it comes to lugging the engine, for those that drive MT, it's pretty easy to avoid if you are downshifting properly and keeping it in gear for the most part above 3K rpm.

I always see videos on Youtube where folks are mashing the throttle on their DCT and taking the car up to redline..........but often times they are in auto mode so the majority of the times they are starting off in the wrong gear before they floor it......hence the potential for lugging it.

[Scharbag]

One data point is not enough to prove or disprove a theory.

Odds are, you simply got lucky and have small crank journals with rod big end bores that are on the large side and thin shells. Tolerance stacking works both ways.

The root issue with the S65 is that the designed clearance is lower than recommended. That means that far greater than 50% of S65s have less than optimal clearance assuming a normal distribution of parts. Given the variance in cranks, rods and shells, it also means that that a certain percentage of factory S65s will have clearances closer to the recommendations of engine builders.

It seems you won the German lottery.

Cheers,

[Transfer]

Great post and this is further evidence that we really don't know if one car will fare worse than another. I think my only takeaway from this is don't be shy about high rpms and redline once fully warmed up, which is how I drive anyway. The other points and variables are too many to know what matters and what doesn't. The German lottery continues.

[tdott]

Those do not "look great" they still show more wear than what is considered "normal" for an engine with that mileage. There should be no noticeable wear to be considered "great".

Read this: http://darkside.ca/tech/CL77-3-402.pdf

[eswaroop]

Originally Posted by Scharbag

One data point is not enough to prove or disprove a theory.

Odds are, you simply got lucky and have small crank journals with rod big end bores that are on the large side and thin shells. Tolerance stacking works both ways.

The root issue with the S65 is that the designed clearance is lower than recommended. That means that far greater than 50% of S65s have less than optimal clearance assuming a normal distribution of parts. Given the variance in cranks, rods and shells, it also means that that a certain percentage of factory S65s will have clearances closer to the recommendations of engine builders.

It seems you won the German lottery.

Cheers,

Pardon my limited knowledge on the topic but I f clearances are lower than recommended as new wont the break in period and wear over time bring them closer to what they need to be? As it seems like the failures seem to be excessive wear of the bearings - they must have passed a point where tolerance and clearance came in line with specs but they just kept wearing out past it ?

[Scharbag]

Originally Posted by eswaroop

If clearances are lower than recommended as new wont the break in period and wear over time bring them closer to what they need to be?

Unfortunately it does not work like that. Hydrodynamic bearings are very precise and clearances must be proper from the start to ensure proper operation.

I am not an engine builder so I would likely not articulate the reasons why properly. Perhaps someone with more knowledge will chime in on the reason why hydrodynamic bearings do not self-clearance properly If initially too tight.

Cheers,

[Prefontaine]

Originally Posted by kimiraikkonen

Interesting post and think there are some merits that you bring up for sure.

Not trying to start another MT vs. DCT type of discussion, but when it comes to lugging the engine, for those that drive MT, it's pretty easy to avoid if you are downshifting properly and keeping it in gear for the most part above 3K rpm.

I always see videos on Youtube where folks are mashing the throttle on their DCT and taking the car up to redline..........but often times they are in auto mode so the majority of the times they are starting off in the wrong gear before they floor it......hence the potential for lugging it.

The DCT downshifts/rev matches prior to re-engaging the clutch to accelerate.

[Merlin_83]

Greetings,

Finally a report of bearings not being totally trashed.

Also where is the data coming from when people state that 50% of the S65's have less than optimal clearance?

The S65 and S85 are not hand built, there built the same as other non M engines are made. Mostly by automation, robotic and some small amount of human interaction. This is what I've been told by several BMW employees (not dealership).

Thanks,
Merlin

[deansbimmer]

Odds are, you simply got lucky and have small crank journals with rod big end bores that are on the large side and thin shells. Tolerance stacking works both ways.

Precisely. The bearings pictured have still worn more than they should have, although not as badly as most S65 bearings we've seen.

Great post and this is further evidence that we really don't know if one car will fare worse than another.......The other points and variables are too many to know what matters and what doesn't. The German lottery continues.

Also spot on. Tolerance stacking is an issue of chance. Since the only way to identify poor bearing wear is by physical inspection (and replacement), it makes sense to just do it. BMW mass produced these engines and the tolerances in question are extremely minute. We give BMW too much credit to assume they'll achieve perfect tolerances down to .0001 on every one of the 70,000 engines produced... If BMW had specified a looser tolerance from the start, we'd be fine, less concerned with negative tolerance stacking, and wouldn't find the need to clutter up the forums with bearing posts.

It's great news that Fogcity received closure on his bearing condition and got some fresh BE's installed at one of the best S65 shops in the USA. However, his experience (as fine and commendable as they may be) with fuels, oils, filters, driving habits, etc is not necessarily a recipe for long life with these engines if your engine was assembled with excessively tight tolerances. What kept these bearings in good condition were the looser factory tolerances- luck of the draw. If your engine is on the "tighter side" then you're in trouble regardless of how you treat your engine. OP won the German Lottery!

[FogCityM3]

Not sure about your framing of bearing condition in relation to the thread or the document, for 90k of some of the hardest driven miles they look far better in terms of the bearing condition thread below. Also, in the doc that you have attached (which we've read this and many similar docs over the years) my bearings don't even look like the 'accelerated wear' ones. Actually on 7 of them would say they as good or in some cases better than the "normal" picture.

The people at Carbahn (fka Dinan who knows a thing or two about building race engines) told me the same thing.

https://www.m3post.com/forums/showth...1253084&page=9

Originally Posted by tdott

Those do not "look great" they still show more wear than what is considered "normal" for an engine with that mileage. There should be no noticeable wear to be considered "great".

Read this: http://darkside.ca/tech/CL77-3-402.pdf

[BayE30]

soo what did Carbahn charge for the RB service? never considered them for this job....

[slowm3]

I agree with a lot of the stuff that FogCityM3 has covered, many factors play into roll about rod bearing. It also depends if you bought a m3 from a previous owner would didn't take care of it, and run through preventive maintenance then rod bearings are a must change asap. I think it really comes down to how the car was treated since day one, especially the break-in phase.

[pbonsalb]

I think it’s a lottery and a sample of one means little. No one has definitely determined a reason for beating failure on these cars. The only thing that is apparent is that factory clearances are on the tight side of standard clearance ranges and that motors vary very slightly in their tolerances — which can add up or “stack” to make the already tight clearances a little tighter, which is probably bad, or a little looser, which is probably good.

[FogCityM3]

Pretty much in line with everyone else in Bay Area. Their service includes spark plug change (and of course oil).

Originally Posted by SFCM3

soo what did Carbahn charge for the RB service? never considered them for this job....

[IanMan]

From a friend who rebuilds S65's and S85's. Manual S85's most commonly show excessive bearing wear compared to SMG cars. I'd be interested to hear what the consensus on S65's is. I did my own bearings on my S85 at 45K miles and they were EXTREMELY worn for such low mileage.

[tdott]

Originally Posted by FogCityM3

Also, in the doc that you have attached (which we've read this and many similar docs over the years) my bearings don't even look like the 'accelerated wear' ones. Actually on 7 of them would say they as good or in some cases better than the "normal" picture.

Nope, the normal ones are not suppose to show any wear, yours are completely worn through the top layer. If they were normal it would be silver with no black spots.



While yours do look better than normal, there is still more wear than what is considered normal. The pictures are also really dark, better picture and I'm sure they would look even worse.

[kimiraikkonen]

Originally Posted by FogCityM3

Pretty much in line with everyone else in Bay Area. Their service includes spark plug change (and of course oil).

• They were charging $3,356 (RBs, oil filter, spark plug change)
  
• or $3,186 without spark plug change
  
• If you wanted motor mounts done at the same time, it was +$359
  
• RBs are BE Bearings, but supposedly a custom spec vs. the normal BE (whatever that means).

So typical Bay Area inflation pricing (vs. the rest of the real USA)....but the Carbahn guys do a standup job on their BMW work.....genuine BMW parts and do have the expertise for debugging.

• And just my opinion here, I think Carbahn's service and pricing has gotten even better since the Dinan sale. I think during the latter years at Dinan, in order to prepare the company for sale, there was a bit of window dressing that was needed, so there used to be a strong upsell pressure on services when going to Dinan...but lately at Carbahn, it's back to how it was originally at Dinan, which was a fair and honest mechanic's view on what needed to be done (vs. what was needed to increase rev-per-visit)

For me, I had to go down to SoCal for something and decided to do mine at MRF since I was down there. Price wise of course a bit of savings, even when factoring in gas for the drive down south. But if I were to do my bearings up here, would probably have paid the extra tax and taken it to Carbahn. Not worth to try to save a few hundred bucks with another shop of dubious BMW (and especially S65) experience.

[FogCityM3]

Your opinion stands in stark contrast to Dinan's and to the pictures themselves (the top layer is BARELY worn).

Even the "normal" ones in the pdf are showing wear!!!

Not sure what the motive/point is here with an argument that is borderline preposterous.

Originally Posted by tdott

Nope, the normal ones are not suppose to show any wear, yours are completely worn through the top layer. If they were normal it would be silver with no black spots.



While yours do look better than normal, there is still more wear than what is considered normal. The pictures are also really dark, better picture and I'm sure they would look even worse.

[FogCityM3]

Agree, they are cheaper than before (or should I say dealer pricing has gone up relatively speaking).

Several other shops are similar in price range for the RB job, depending on bearings chosen.

For me it was one of two choices I trusted and this one was more convenient while being similar priced.

FWIW they offer the typical Dinan 2 yr warranty. Have hade a long-standing relationship with the guys there for several years.. it's all the same people and they're truthful (in contrast to what some people in this thread are wrongly alleging in terms of "feel good" customer service. In contrast, they are brutally honest!).

Originally Posted by kimiraikkonen

• They were charging $3,356 (RBs, oil filter, spark plug change)
  
• or $3,186 without spark plug change
  
• If you wanted motor mounts done at the same time, it was +$359
  
• RBs are BE Bearings, but supposedly a custom spec vs. the normal BE (whatever that means).

So typical Bay Area inflation pricing (vs. the rest of the real USA)....but the Carbahn guys do a standup job on their BMW work.....genuine BMW parts and do have the expertise for debugging.

• And just my opinion here, I think Carbahn's service and pricing has gotten even better since the Dinan sale. I think during the latter years at Dinan, in order to prepare the company for sale, there was a bit of window dressing that was needed, so there used to be a strong upsell pressure on services when going to Dinan...but lately at Carbahn, it's back to how it was originally at Dinan, which was a fair and honest mechanic's view on what needed to be done (vs. what was needed to increase rev-per-visit)

For me, I had to go down to SoCal for something and decided to do mine at MRF since I was down there. Price wise of course a bit of savings, even when factoring in gas for the drive down south. But if I were to do my bearings up here, would probably have paid the extra tax and taken it to Carbahn. Not worth to try to save a few hundred bucks with another shop of dubious BMW (and especially S65) experience.

[MPower7]

Interesting why they went with the Original bolts over ARP? Don't they have an 11 step tightening process?