Replace main bearings?

[evangelion139]

Originally Posted by tdott

That's because every engine is different. There is no set mileage where they fail.
No one can tell you unless they take them apart or have a crystal ball. If you take it a part to inspect it, you might as well change them.

There have been failures under 10k miles, under 100k and failures past 100k miles. There is a thread and a list of failures you can take a look at.

makes sense

[dar2008]

Originally Posted by evangelion139

seems like there isn't a consensus of how much mileage until the rod bearings would break...

i've got 41k miles on my 2010 (pre-LCI) e92m3 and still debuting whether to upgrade the rod bearings now, or should I wait until 50k miles?

You’ll receive a variety of responses here to this question.

Some will be from garages who carry out RB replacement works. They can often be seen posting pictures showing the old RB’s, with at least 1 or 2 showing heavy wear down to metal or copper. The text accompanying such posts will often say things like: “this one was caught just in time”.

Others will post that they’ve had their car’s RB’s changed by one of the garages above and confirm it’s money well spent for piece,… sorry ‘peace’ of mind (for some reason posters always spell peace wrong in this context)

Yet others will say it’s not an issue and so long as you look after the car, you’ll be fine,… probably.

Ultimately it’s for you to decide what’s right for you and your car based on your knowledge of its history vs the risk of them actually failing. Here’s the anecdotal evidence to help you decide:-

1. There have been a small number of RB failures on these engines with both the old and new bearing design - note the design was changed on all cars built from 09/2010, not because BMW recognised a flaw in them, but rather to comply with new EU regs on copper and lead usage in manufacturing. Importantly the clearances remained the same between the two types.

2. BMW do not admit to there being an issue with the RB’s and do not offer a service to replace them.

3. It’s quite hard to find stories of RB failure on these cars in any great numbers - there are some, for sure, but it’s incredibly rare to hear or read about them with any kind of regularity that would tie in with garages claiming “just in time”.

4. However, a post / survey on this site attempted to collate details of all engines that had experienced RB failure, worldwide. The number they’ve arrived at is approx. 130, although when you look into the details not all of that number could be attributed to a straightforward RB failure.

5. Just over 65,000 S65 powered M3’s were produced for the global market. 130 cars represents 0.2% failure, or 99.8% non-failure. Obviously the M3Post survey will not have collated every failure worldwide, although it is US centric, which was by far the biggest destination for E9x M3’s.

6. Of the failures recorded there was a high likelihood that one of more of the following factors were present.

- Car was tracked
- Car was supercharged (I believe it’s a recommendation when supercharging to change them now)
- Múltiple previous owners with no evidence the engine was always warmed up properly
- Poor / missing service history

7. Beyond those failures, there are plenty (and I mean loads) of these cars >100k miles running on original RB’s and quite a few >200k miles - the forums are full of them. Mileage does not appear to be as big a factor as those other items outlined above.

So, in summary, if you look after your car with regular oil changes and proper warming up as per the handbook, it’s highly unlikely your RB’s will fail.

With all that said, if you’re unable to really enjoy your car without worrying about this, then you should probably get them done, for piece,…sorry, peace of mind.

YMMV

[gkgsvensson]

Do the RB's first, and do them soon. They are not a big deal to install (I did them myself in a weekend) and they pretty much add value to the car equivalent to the cost (Expect 2500-3000 with motor mounts). I recommend the classic BE/ARP combo as they appear to be a permanent fix. As for main bearings, the cost to replace is on the same order as getting a used engine. So in my opinion, if they blow, they blow (but they probably wont). Also forums tend to have a negative bias on reliability issues and stuff gets easily overblown. This is one of them. Now go out and drive the crap out of your M3

[evangelion139]

Originally Posted by dar2008

You’ll receive a variety of responses here to this question.

Some will be from garages who carry out RB replacement works. They can often be seen posting pictures showing the old RB’s, with at least 1 or 2 showing heavy wear down to metal or copper. The text accompanying such posts will often say things like: “this one was caught just in time”.

Others will post that they’ve had their car’s RB’s changed by one of the garages above and confirm it’s money well spent for piece,… sorry ‘peace’ of mind (for some reason posters always spell peace wrong in this context)

Yet others will say it’s not an issue and so long as you look after the car, you’ll be fine,… probably.

Ultimately it’s for you to decide what’s right for you and your car based on your knowledge of its history vs the risk of them actually failing. Here’s the anecdotal evidence to help you decide:-

1. There have been a small number of RB failures on these engines with both the old and new bearing design - note the design was changed on all cars built from 09/2010, not because BMW recognised a flaw in them, but rather to comply with new EU regs on copper and lead usage in manufacturing. Importantly the clearances remained the same between the two types.

2. BMW do not admit to there being an issue with the RB’s and do not offer a service to replace them.

3. It’s quite hard to find stories of RB failure on these cars in any great numbers - there are some, for sure, but it’s incredibly rare to hear or read about them with any kind of regularity that would tie in with garages claiming “just in time”.

4. However, a post / survey on this site attempted to collate details of all engines that had experienced RB failure, worldwide. The number they’ve arrived at is approx. 130, although when you look into the details not all of that number could be attributed to a straightforward RB failure.

5. Just over 65,000 S65 powered M3’s were produced for the global market. 130 cars represents 0.2% failure, or 99.8% non-failure. Obviously the M3Post survey will not have collated every failure worldwide, although it is US centric, which was by far the biggest destination for E9x M3’s.

6. Of the failures recorded there was a high likelihood that one of more of the following factors were present.

- Car was tracked
- Car was supercharged (I believe it’s a recommendation when supercharging to change them now)
- Múltiple previous owners with no evidence the engine was always warmed up properly
- Poor / missing service history

7. Beyond those failures, there are plenty (and I mean loads) of these cars >100k miles running on original RB’s and quite a few >200k miles - the forums are full of them. Mileage does not appear to be as big a factor as those other items outlined above.

So, in summary, if you look after your car with regular oil changes and proper warming up as per the handbook, it’s highly unlikely your RB’s will fail.

With all that said, if you’re unable to really enjoy your car without worrying about this, then you should probably get them done, for piece,…sorry, peace of mind.

YMMV

appreciate the detailed response!! quite a surprise that BMW didn't acknowledge the design failure, but maybe they have a point if the failure rate is below 1%...