Rod Bearing Break-in (hint: there isn't a need)

[IamFODI]

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/55462-dumb-question-thread-no-flaming-allowed?p=123508#post123508

[Jimbo's M]

That’s not for the “Rod Bearing” replacement break in. That’s whole brand new engine break-in Terra.

Regardless. As I've said once or twice here, I've gone through THREE break-ins. Why is it all three (dealer stated) needed the 105mph, 5500rpm limit, but the last two were okay for WOT? Not the way I remember it. Whether the dealer and/or BMW NA is full of shit, I have NO idea as I have ZERO dog in this fight. I merely report the news.

[tnord]

There was a lively thread on former M3F about breaking in rod bearings. There are also DIY's, here and elsewhere, with smatterings throughout warning people about the need to break in their bearings. Typically, its covering the rod bearings that someone has just replaced.

With that, you may enjoy this timely video from Andre Simon at HP Academy. Among other myths dispelled, he addresses the false statements about needing to break in your bearings. Fundamentally, it simply makes sense.

The video will jump to 3:22 covering the topic: https://youtu.be/5Ruk6GLJgbA?t=202

I listened to about 10min of this, and it's consistent with everything I learned about race engines, and observed as well. I had one friend who had a very nice engine built, and did a very slow, deliberate break in period on advice of his builder. He was down a bit on power, dyno confirmed, compared to the rest of us. The rest of us would run some dino oil through the engine until it came to temp, made sure nothing was leaking, change the oil again, and sent it on the dyno or track.

As mentioned in the video, breaking in is needed to seal rings against newly honed cylinder walls, not "smooth out" bearings or whatever is expected to happen during break in.. Higher cylinder pressures from high rpm/wot helps this process, will boost compression numbers, and power.

If it makes you feel any better the PPI done by technicians as cars are pulled off the transport truck includes WOT pulls to redline. Or at least it did for Mazda during the time I was working there.

[Jimbo's M]

If it makes you feel any better the PPI done by technicians as cars are pulled off the transport truck includes WOT pulls to redline. Or at least it did for Mazda during the time I was working there.

Just throwing this out as a "yeah but" as I have little idea...but, does Mazda have a motor with piston speeds that the S54 has which upon debut was just shy of the BWM F1 V10 of the day? Maybe that matters a little..

[old///MFanatic]

I've gone through THREE break-ins. Why is it all three (dealer stated) needed the 105mph, 5500rpm limit, but the last two were okay for WOT? Not the way I remember it.

BMW only states no full throttle on initial engine break-in. When we picked up my M3 after the Rod Bearing recall there was nothing about “no full throttle” (for broken-in engines) for the Rod Bearing Recall. That’s how I remember it. And documents backup.
There are stickers from BMW when BRAND NEW to not go over 2/3rds the full speed in gear and no full throttle/kick down. Maybe your dealership only had those and gave you that? But for the Rod Bearing Recall stickers BMW supplied dealerships were this one.

[Jimbo's M]

BMW only states no full throttle on initial engine break-in. When we picked up my M3 after the Rod Bearing recall there was nothing about “no full throttle” (for broken-in engines) for the Rod Bearing Recall. That’s how I remember it. And documents backup.
There are stickers from BMW when BRAND NEW to not go over 2/3rds the full speed in gear and no full throttle/kick down. Maybe your dealership only had those and gave you that? But for the Rod Bearing Recall stickers BMW supplied dealerships were this one.

Fine. If I don't remember correctly or got bad info, I really don't care. I've got ~19 years on this third set of bearings and the motor is strumming along. That's what matters to me. BTW, just to nit pick, it wasn't a 'recall', it was a 'service action'. A recall is mandated.

[old///MFanatic]

I've gone through three break-ins. Why is it all three (dealer stated) needed the 105mph, 5500rpm limit, but the last two were okay for WOT? Not the way I remember it.

I like how you’re approaching this! Using logic to see what makes most sense. So let’s ponder, do you think BMW supplied BMW “Rod Bearing Recall” break-in stickers different between months? Or was their probably only the one type produced? And does that one match what the SIB states in document.
I’m just clarifying there doesn’t seem to be no WOT listing for the Rod Bearings. Not that it really matters lol. I’m just like the facts straight or confirmed. My burden when reading things. Sorry.

[DropTopKingM3]

What if you did both rod bearings and Vanos together ?

[old///MFanatic]

Fine. If I don't remember correctly or got bad info, I really don't care. I've got ~19 years on this third set of bearings and the motor is strumming along. That's what matters to me. BTW, just to nit pick, it wasn't a 'recall', it was a 'service action'. A recall is mandated.

Sorry I posted again before reading this. Not trying to drag on.
And yep I was a little apprehensive about using term recall but figured it was easier reading for topic.
Mine was done Jan 2005. So had 16 years but recently did mine because “projects” on the oil pan gasket and front suspension. Bearings looked great still. Thanks for your time in discussion sir 👍🏻

[Jimbo's M]

So let’s ponder, do you think BMW supplied BMW “Rod Bearing Recall” break-in stickers different between months? Or was their probably only the one type produced?

The only response I have to this is that build dates from ~10-01 thru 3-02 (mine's a12-01) had to do bearings twice. Whether there's a difference between all those replacements and what's what and who's who and since I only bought one M3, I have no idea and doubt we'll ever know. Time for Mulder and Scully.

[S54B32]

FYI: Without reading the whole thread.... on the actual (looked up today) official BMW dealer instructions for rodbearing change there is no break in required. And even professional engine builders (here in germany) will tell you the same with shell change only. (Throw them in, warm it up and full send...)
I did the same and had never a problem, and this car gets redlined on a daily base.
BUT "break in" is not a bad thing, so nothing wrong with it, beside that it is not necessary.

[m3nt0s]

There’s no downside to following the TSB.

[tnord]

Just throwing this out as a "yeah but" as I have little idea...but, does Mazda have a motor with piston speeds that the S54 has which upon debut was just shy of the BWM F1 V10 of the day? Maybe that matters a little..

I don't think that really matters. Mazda's warranty exceeds BMW and they would be more interested in longevity. I'd be surprised if Mazda's PPI procedure was unique also. Specialist cars like Singer, run their engines on an engine dyno prior to installation. Do you think they limit that to 5500 rpm?

What I can't wrap my head around is why they had that procedure to start with. Did they know they f'd up before production and put that procedure in there to try and avoid catastrophic failure?

That said, in the case of rod bearing replacement, I agree that you've got nothing to lose (other than having the patience to drive that way for 1k miles) by following the procedure. I actually just got my car back from rod bearing replacement a couple days ago, and I'll sort-of be following it. The shop drove it around a bit keeping it under 4500 to make sure all was good, I've probably driven it another 20miles not exceeding 6k rpm, but I've probably hit full throttle a few times. I have a 400mile road trip coming up where it won't be difficult to baby it, so I'll probably do that then call it good.

[lemoose]

In an ideal world bearings don't touch the crank. In the same ideal same world, S54 bearings wouldn't have a wear issue to begin with.

[tnord]

In an ideal world bearings don't touch the crank. In the same ideal same world, S54 bearings wouldn't have a wear issue to begin with.

this ideal world is where every other mfg lives.