E92 M3 Maintenance

[br1anwv]

Hi all, I’m looking to buy an E92 M3. I’ve done all the research with maintenance and I’m just wondering if the throttle actuators and rod bearings are a recurring problem? After they are both replaced will the eventually go bad again, with higher tolerance rod bearings? Also wondering about any other issues and if I can do them myself.

[kolosy]

there's a recent thread on the bearings, search for "be bearing longevity" or something to that effect. consensus is BE bearings are generally "lifetime," OE bearings are a waste of money. I'd view TAs as a wear item.

[IamFODI]

Originally Posted by br1anwv

Hi all, I’m looking to buy an E92 M3. I’ve done all the research with maintenance and I’m just wondering if the throttle actuators and rod bearings are a recurring problem? After they are both replaced will the eventually go bad again, with higher tolerance rod bearings? Also wondering about any other issues and if I can do them myself.

Both of these issues are overblown (to varying extents) and a lot of the prevailing narrative about rod bearings has been... let's just say, challenged.

TAs can be a "cross that bridge when you get there" thing. You can replace them preventatively if you want but it's not the kind of problem that could blow up your engine.

Rod bearings: Buckle up....

Yes, the original leaded rod bearings seemed to wear excessively. Quite common to see them come out with copper showing.

However, contrary to prevailing opinion until now, the updated lead-free BMW rod bearings don't actually seem to wear excessively. People thought they did because they discolor with use, but that discoloration has turned out to be purely superficial and does NOT represent wear-through of the top layer as people had assumed. We have seen some evidence of light surface wear beyond that in some cases, but we have yet to see a single set that has definitely worn through to the copper in anything like normal use.

Meanwhile, BE Bearings's own testing has confirmed the obvious prediction that increased rod bearing clearances reduce oil pressure, which could have implications for other parts of the engine – and some of those parts, like main bearings, are a whole different level of hurt if they fail. This raises questions that no one's even trying to address. No one's gathering the relevant stats from engines in the wild (i.e. engine failures in general, not just spun rod bearings with everything else being fine), and no one outside of BMW has done the kind of testing that could figure it out any other way.

I'm not saying extra-clearance rod bearings will blow up something else in your engine. The point is that it's an open question (which should have been asked years ago, but whatever). In terms of cost and headache, even a minor hit to the longevity of something like the main bearings could easily offset a massive increase in rod bearing lifespan, so we need to know more than we currently do.

Bottom line:

- If the car you're looking at has original (pre-2010) rod bearings, then yes, treat them as a wear item.
- If it has the updated BMW rod bearings, don't sweat it. The risk is nowhere near enough to justify ripping into the engine, risking assembly errors, contamination, etc.
- If it has aftermarket rod bearings, it's anyone's guess.

[br1anwv]

Replying to IamFodi, Most of the cars I’m looking at have had rod bearings replaced. So if they’re pre 2010, I should treat it as a wear item and do them every 50-60k miles? And if it’s 2010 or newer I should just let them be?

[kolosy]

Originally Posted by IamFODI

Both of these issues are overblown (to varying extents) and a lot of the prevailing narrative about rod bearings has been... let's just say, challenged.

TAs can be a "cross that bridge when you get there" thing. You can replace them preventatively if you want but it's not the kind of problem that could blow up your engine.

Rod bearings: Buckle up....

Yes, the original leaded rod bearings seemed to wear excessively. Quite common to see them come out with copper showing.

However, contrary to prevailing opinion until now, the updated lead-free BMW rod bearings don't actually seem to wear excessively. People thought they did because they discolor with use, but that discoloration has turned out to be purely superficial and does NOT represent wear-through of the top layer as people had assumed. We have seen some evidence of light surface wear beyond that in some cases, but we have yet to see a single set that has definitely worn through to the copper in anything like normal use.

would love to see how you're substantiating this.

_edit_ i see you're chatting on the rb condition thread, can leave this convo there then.

[IamFODI]

Originally Posted by br1anwv

Replying to IamFodi, Most of the cars I’m looking at have had rod bearings replaced. So if they’re pre 2010, I should treat it as a wear item and do them every 50-60k miles? And if it’s 2010 or newer I should just let them be?

The question isn't just whether they've been replaced, but what they were replaced with.

The old rod bearings haven't been made in many years, so you most likely won't see any of those in any S65 that has had rod bearings replaced unless the replacement was done in 2010 or before.

If they were replaced with the updated BMW OE bearings at a GOOD shop, you should be fine for at least as long as you're likely to own the car. Or at least, they're not worth messing with. If you're super worried, consider them a 100k mile maintenance item (again, at a GOOD shop).

If they were replaced with aftermarket, I don't know how to advise you except that anyone saying it's one-and-done is operating on incomplete info. They're not wrong, necessarily. Early evidence about the rod bearings themselves is promising. We just don't know what the long-term outlook is on the engine as a whole. I'm not sandbagging or trying to low-key tell you aftermarket bearings are a bad idea or anything. I'm saying the info out there doesn't warrant a solid conclusion either way.

If they haven't been replaced at all, it'll be tough to say what bearings are in there. 2008 and 2009 definitely had the old ones. 2012 and 2013 definitely had the new ones. AFAIK (someone check me on this though), the new bearings trickled in through 2010 and 2011, so some engines in those years got the old ones and some got the new ones.

If somehow you discover that a car you're looking at has the original pre-2010 rod bearings, just replace them immediately after purchase.

[IamFODI]

Originally Posted by kolosy

would love to see how you're substantiating this.

_edit_ i see you're chatting on the rb condition thread, can leave this convo there then.

Look for my and Assimilator1's posts in that thread. Please feel free to engage if you disagree.

Long story short: he and others have started sanding down used updated BMW rod bearings. In every case so far, the discolored part goes away, leaving a perfectly gray/silver surface, long before actual copper starts to appear. The copper layer looks very different from anything we've seen in pics of those bearings, at any mileage, in any use case remotely resembling normal.

In some cases, there's a patch on the bearing where the longitudinal grooves (which are mainly for debris evacuation) are noticeably shallower or no longer visible. This is the only real evidence we have of wear beyond the discoloration. But, again, it's only within the top layer. Glyco (the manufacturer) says it's not a critical issue.

Glyco says that some of their bearing alloys develop a thin layer of oxidation in use, and that a small amount of local wear combined with tight clearances results in good overall function of the bearing. It's far more likely that this, not excess wear, is what we're seeing in these updated BMW rod bearings.

The oil pressure thing is the most recent topic being discussed, so those posts should be easy to find (just go to the last pages as of right now).

[VR1]

Originally Posted by br1anwv

Hi all, I’m looking to buy an E92 M3. I’ve done all the research with maintenance and I’m just wondering if the throttle actuators and rod bearings are a recurring problem? After they are both replaced will the eventually go bad again, with higher tolerance rod bearings? Also wondering about any other issues and if I can do them myself.

I’d rely on the experts

deansbimmer

[GinTonic]

Is there any substantial evidence of worn out aftermarket rod bearings? e.g. VAC, BE, etc....