[james4321]

hello guys, I have been driving N55 engines for a long time now. My F30 335i PWG has never had an issue with conrod bearings. I sold it when 116k miles on the clock. And I went for 2016 M235i as I love how it perform and look. It has 129k miles. I went through so many topics and FB groups to check how is M235i engine doing with rod bearings. And I think it’s 50/50. some say ‚do not fix when it’s not broken’ and some ‚do preventative change’. Even there were few guys saying, that 2014+ N55 has upgraded bearings which are much strongwr than early N55’s. Ofcourse shit happens and even the strongest stuff can brake, but is M235i really struggling with this issue? Is it common? Most likely I will have a look on them and change during the winter, as my oil pan gasket starts to leak, but I’m just qurious. My car had two owners before me, I know the history. 0-80k miles OCI every 10-12k miles, 95% highway mileage. 80-129k miles 6-7k OCI. Tuned at 100k miles. What do you think, was it well maintained? I’m asking, because in my country people are going crazy, it’s a big panic now and 99% of them is changing the bearings as we have a rumour that N55 has this problem

[Cos270]

Originally Posted by james4321

hello guys, I have been driving N55 engines for a long time now. My F30 335i PWG has never had an issue with conrod bearings. I sold it when 116k miles on the clock. And I went for 2016 M235i as I love how it perform and look. It has 129k miles. I went through so many topics and FB groups to check how is M235i engine doing with rod bearings. And I think it’s 50/50. some say ‚do not fix when it’s not broken’ and some ‚do preventative change’. Even there were few guys saying, that 2014+ N55 has upgraded bearings which are much strongwr than early N55’s. Ofcourse shit happens and even the strongest stuff can brake, but is M235i really struggling with this issue? Is it common? Most likely I will have a look on them and change during the winter, as my oil pan gasket starts to leak, but I’m just qurious. My car had two owners before me, I know the history. 0-80k miles OCI every 10-12k miles, 95% highway mileage. 80-129k miles 6-7k OCI. Tuned at 100k miles. What do you think, was it well maintained? I’m asking, because in my country people are going crazy, it’s a big panic now and 99% of them is changing the bearings as we have a rumour that N55 has this problem

Get an oil analysis and that should be a pretty good indicator. In general, from my research the N55’ in the M235i appear to hold up just fine with good maintenance and no track duty. If either of those enter the equation (and not under your ownership) I would probably replace the rod bearings at your mileage if the oil pan is coming off anyways.

[mecheng77]

If you track the car then definitely but while the oil pan is dropped how much extra money will it be? It might be worth it.
The bearing issue is mainly from high G force

[james4321]

I was told, that It will be extra 500$ for bearings.
No track days. I’m driving mostly in the city, gently in comfort mode. Maintenance/history like I typed in first post.
Probably I will change them in winter, but I’m like do we realy have a problem with bearings?

[XutvJet]

I really wouldn't bother if you don't use the car on high sustained G track driving. All M235s N55s have S55 rod bearings, S55 forged rods, and forged crank. If you do track driving, then drop the oil pan and install the S55/M2 higher capacity oil sump system which lets the N55 reliably handle track driving.

Used oil analysis is a good thing to do every once and a while too.