CZ 75

Having an interesting conversation with my BiL. He claims that I will eventually have to replace my rod bearings because of the tq I'm pushing on this engine. Obviously, using good quality oil and changing it every 5k. I don't know much about that aspect of when it comes to vehicle maintenance, even more so with this car(i've only owned it for 4 months). Curious what the hive thinks?

CerBErusM113

Lol is your BiL a BMW guy? Lol this isn't an e90 M3, M157 motors can take being tuned and have a solid bottom end. Now, I'm not saying that there haven't been failures in these motors but, it's not because of wear on the bottom end because of the TQ. They're made to push that kind of power, just make sure ignition is good and it's being oiled properly.

PeterUbers

Not needed for the m157.

CZ 75

Haha no, he's not. He's never worked with tuned vehicles so he was just making that assumption. Funny thing is, I typed in Google "are rod bearings a maintenance item on tuned vehicles" and all of the results were for BMW's. Anyways, I told my BiL that the M157 is more than capable of handling a tune since MB underrates the power in these engines anyways. Besides, I don't drive mine hard.

kenneyd

Lol, rod bearings are what BMW guys have to deal with, we just get a little oil in some of our sensors

It doesn't matter if you're running 50 horsepower or 850, it should never be a metal or metal contact bearings. If there is, it's a matter of minutes before they fail.
I've never heard of any bearing failures with an m157 or any Mercedes to date

CZ 75

Thanks for the reassurance Kenny. Btw keep up the valuable work on your YT channel. I know it doesn’t make you that much money, but your content is invaluable - as is the knowledge other folks here have shared with me in this forum thus far. Never thought I’d own an AMG(or any Mercedes for that matter) and yet here we are lol.

cotmfk

It's too true! The BMW community has to replace rod bearings on basically all of the M cars, until the more recent motors (2014+).

But, it seems like all of them have some sort of fatal flaw (similar to the oil in sensors on E63). For the F8x M3/4, rod bearings are fine and can handle a ton of power, but instead you have the crank hub problem, where the crank hub bolt can work itself out and grenade the motor. So, now you are seeing used car posts for those M3s advertising "crank hub fix already done." The pricing on that crank hub fix varies wildly... I've seen quotes from $2,500 all the way to $7500, but the most common is between $5-6k.

altesporsche

He must be working on a lot of BMWs lol, Naaaa rod bearings shouldn’t be a concern on this engine. There are many 157/278 motors running stupid numbers with no issues. This usually becomes and issue when a manufacturer uses very tight tolerance like BMW does.

CZ 75

No, he's never worked on bimmers. Dude's very knowledgable but doesn't really know much about the effects of tunes on vehicles so he was throwing some assumptions out there. Myself, I know a lot less than him(he's a diesel mechanic) so I told him that I'd ask MBworld. Shared this thread with him yesterday and he conceded lol.

I.T. Guy

The bearings might not be a concern
But the rods are! The nannies don't seem to protect the engine as well on (aggressively) tuned cars when there is ping, knock, bad gas, bad spark, older plugs, any worn ignition items, rods like to give it up.
If you are tuned it is imperative to keep everything running tip top. And if you fill with less octane or bad gas don't WOT until it's all perfect again.
And find a safe tuner. Tuners that wring out that last 20-40HP for the dyno-war win are putting things too close to the edge so when something does go "wrong" (old plugs, bad coil, bad gas, tired fuel pumps) it's not pretty.

Stay safe out there!