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      01-15-2022, 03:53 PM   #1
714BMW
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N55 Rod Bearing Issues

Hello everyone,

Seeking peace of mind as I've been reading way too much into the forums. Yes I realize this is counterintuitive since I'm asking to read even more into the forums.

I have a '16 M235i 6MT with 25k miles and have been reading a lot about oil starvation and engine seizures on the N55's. More common on PWG models but still see quite a few on EWG models. Most of the stories are from the track but have heard a few from normal driving.

I'm Stage 2 custom e30 pushing roughly 17 psi and never track it. No doughnuts or drifting either. I usually canyon the car about twice a month when I switch back to 91 tune and some of the turns can sustain fairly high G forces. After hearing some horror stories about these N55's blowing up, even with the improved rods/crankshaft that the M235i engines get, I guess I'm a bit worried every time I want to push the car in canyons or daily driving. Love the car and want to be able to drive it for a while longer.

I change oil every 3-5k miles with 5w-40 as I'm in Southern California and it's usually warmer here. Never have red lined as I usually shift at 6k since the power usually drops off around there.

Can anyone pitch in with their own experiences or advice as to avoiding such a failure? Last thing I want is to end up paying nearly 20k for a replacement engine. Anyone usually canyon their car without issue? Any information is appreciated.

Thanks again.
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      01-15-2022, 05:54 PM   #2
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If you want a piece of mind then upgrade to the S55 oil pumps and sump.
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      01-16-2022, 12:04 AM   #3
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Quote:
Originally Posted by Dumaurier7 View Post
If you want a piece of mind then upgrade to the S55 oil pumps and sump.
^ S55 oil component upgrades would be the best. Keep your maintenance schedule on top and I'd start doing your changes every 2-3k miles considering your modifications.

Other than that the N55 is still one of the most reliable bmw engines, they've been out for about a decade but have proven themselves, of course they still have their weak spots.
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      01-16-2022, 11:53 AM   #4
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Rod bearing failures on the EWG N55s are rare. Like you said, when they fail in the EWG N55s, it's usually because of high lateral sustained Gs during track driving. The fix is the S55 oil sump parts swap.

With that said, with your mods, you are pushing the safeguard limits of the N55. One bad knock event could hammer the piston so hard that it squashes the oil film between the rod bearing and crank.

I strongly suggest never going moderate to heavy throttle in a tall gear (3rd and above) at rpms below 4000rpms. This is called a high load situation which can introduce a huge surge of boost and potentially low speed preignition (LSPI). In stock form, then DME is quick enough to respond to keep this from happening. With Stsge 2 and beyond mods, the DME might not be able to keep up.

While good practice,, changing oil often really isn't going to do much for preventing spun bearings.
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      01-16-2022, 02:41 PM   #5
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Quote:
Originally Posted by XutvJet View Post
Rod bearing failures on the EWG N55s are rare. Like you said, when they fail in the EWG N55s, it's usually because of high lateral sustained Gs during track driving. The fix is the S55 oil sump parts swap.

With that said, with your mods, you are pushing the safeguard limits of the N55. One bad knock event could hammer the piston so hard that it squashes the oil film between the rod bearing and crank.

I strongly suggest never going moderate to heavy throttle in a tall gear (3rd and above) at rpms below 4000rpms. This is called a high load situation which can introduce a huge surge of boost and potentially low speed preignition (LSPI). In stock form, then DME is quick enough to respond to keep this from happening. With Stsge 2 and beyond mods, the DME might not be able to keep up.

While good practice,, changing oil often really isn't going to do much for preventing spun bearings.
Understood. I should be fine as there's a good chance it won't see anything except for normal street driving and canyons.

Now, this is definitely interesting/concerning since I send data logs to my tuner in 3rd gear from 3k-6k RPMs. My revisions are done now but I will make sure to keep away from this in the future.
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      01-16-2022, 08:35 PM   #6
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Or you could just baffle the pan
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      01-18-2022, 06:49 PM   #7
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I have 65k miles, plenty of donuts/drifting, plenty of backroad twisty (similar to cali canyons but through the roads in Southern NY) time, on stage2+ e30.

Be nice to your cold engine, don't lug at low RPM, use good gas, and stay on top of your plugs/coils/oil. It is difficult to sustain the G's needed to cause pan based starvation at lower speeds (less than 80ish) on non 200 or less treadweight tires. I can't imagine you are pushing 80+ consistently through cali canyons and if you are, thrice revised and forged rod bearings are not what you should be worried about.

I will add that there are a ~few~ failures immediately followed by OFHG jobs, or even just oil changes. There are also a few grenades caused by OFHG leaking onto belts that slip off and then get sucked into the front main seal by the crank. If you are SERIOUSLY concerned unplug your injectors and crank the engine twice before you restart under power after an oil related job to make sure the oil system is primed. And change your OFHG the second it begins seeping (like I did at 50k)
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      02-02-2022, 04:23 PM   #8
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Sump Baffle Option

Anyone have any experience with this sump baffle?

MMR Baffle Sump Plate N55 - BMW M135i, M235i F20 F21 F22 F23It’s well documented that the N55 engine found in the M135i and M235i is prone to oil starvation issues when pushed hard on the road and even more so when used on track.

The MMR Performance sump baffle has been extensively engineered from the ground-up to provide effective oil control, reducing surge and maintaining a more constant oil pressure; it's the ultimate bolt-in solution available to protect your engine's longevity.

Featuring a total of 7 one-way oil control flaps and specific baffling, the T-6061 anodized MMR sump baffle has been tested over thousands of miles of track and road use where the data we collected has proven it's effectiveness, plus highlighted that it's typically most susceptible without a baffle under hard braking.
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      02-03-2022, 12:54 PM   #9
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Quote:
Originally Posted by ferraricare View Post
Anyone have any experience with this sump baffle?

MMR Baffle Sump Plate N55 - BMW M135i, M235i F20 F21 F22 F23It’s well documented that the N55 engine found in the M135i and M235i is prone to oil starvation issues when pushed hard on the road and even more so when used on track.

The MMR Performance sump baffle has been extensively engineered from the ground-up to provide effective oil control, reducing surge and maintaining a more constant oil pressure; it's the ultimate bolt-in solution available to protect your engine's longevity.

Featuring a total of 7 one-way oil control flaps and specific baffling, the T-6061 anodized MMR sump baffle has been tested over thousands of miles of track and road use where the data we collected has proven it's effectiveness, plus highlighted that it's typically most susceptible without a baffle under hard braking.
I have one
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      03-17-2022, 09:42 PM   #10
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A few of us just installed the MMR baffle in the 3 series recently:

https://f30.bimmerpost.com/forums/sh....php?t=1893538
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      08-02-2022, 03:41 PM   #11
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So, i have an EWG N55 and I spun a rod bearing a couple weeks ago. I wasnt tracking the car however I was merging onto the freeway.

Im found a motor with 15k Miles on the clock and im going to be installing VAC Motorsport bearings and APR head studs.

Unfortunately i have Xdrive so installing the S55 oil pan is not an option. (Althought i am curious if i could install the S55 oil pump and keep the n55 Xdrive Pan)

I highly recommend you guys do your oil changes on time and if you guys ever have to, upgrading the bearings and the oil pan is an absolute must for long term reliability.

Mind you it seems like im an outlier amongst EWG owners.
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      08-02-2022, 06:04 PM   #12
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Quote:
Originally Posted by Jelly_Belly View Post
So, i have an EWG N55 and I spun a rod bearing a couple weeks ago. I wasnt tracking the car however I was merging onto the freeway.

Im found a motor with 15k Miles on the clock and im going to be installing VAC Motorsport bearings and APR head studs.

Unfortunately i have Xdrive so installing the S55 oil pan is not an option. (Althought i am curious if i could install the S55 oil pump and keep the n55 Xdrive Pan)

I highly recommend you guys do your oil changes on time and if you guys ever have to, upgrading the bearings and the oil pan is an absolute must for long term reliability.

Mind you it seems like im an outlier amongst EWG owners.
Sorry to hear that man. Can't believe it spun just getting onto a highway. If you don't mind me asking, how many miles were on the car when it spun?

I'm on E85 so I usually do my oil changes around 3k-4k intervals as it eats through the oil a bit faster than pump gas.
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      08-06-2022, 09:54 PM   #13
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It has 68 000miles. Car is bone stock, was running on 91 octane.
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      08-07-2022, 07:50 AM   #14
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Quote:
Originally Posted by Jelly_Belly View Post
It has 68 000miles. Car is bone stock, was running on 91 octane.
more than likely was on its last leg due to previous owner. Don't beat yourself up
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      08-09-2022, 09:55 AM   #15
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Just asked a similar question earlier about doing donut in the m235i. If its any consolation, I went out and had some fun doing donuts in my friends parking lot. I didn't have any oil starvation issues. I really believe that the problems you hear about on the forums are going to be amplified. It's a confirmation bias thing.

Any car will have oil starvation issues if you sustain high g's for a long period of time unless you have a dry sump oil system. You're fighting against the laws of physics. Its not a shortcoming of the cars engineering.

If you're going through a 8 second sweeper corner at 80 miles an hour and you're driving on race tires, you will most likely have problems. You'll also have problems if your low oil light comes on and you decide to go romp on it. Other than that I wouldn't be too concerned.
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      08-09-2022, 01:46 PM   #16
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You can certainly spin a rod bearing on these cars doing donuts assuming you're doing lots of donuts and get going at a good clip to the point that the oil sloshes up against one side of the pan.

It's also hell on the motor in general has you're running at a high rpm and hardly any air is moving across the various heat exchangers like the intercooler, oil cooler, or radiator.

A couple of donuts? No biggie. 30 seconds of donuts? Not advised.

These motors can handle a lot of abuse and spun rod bearings aren't super common, but I will add these motor are expensive as hell and generally hard to find as the M235 is a rare car in the US and the N55 motor in the M235 is specific as it has a forged crank vs the cast crank found in all other N55s except for the 2016-2018 M2 (forged crank as well). You'll end up spending $8-12K on a used M235 motor assuming you find one. Or you can spend $15K on a remanufactured short block from BMW and spend $5K to install it.
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      08-09-2022, 08:14 PM   #17
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All of the bearing issues I’ve seen are from the F30 side, I thought the M2/35 got better spec’d bearings?
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      08-09-2022, 09:46 PM   #18
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Quote:
Originally Posted by AmuroRay View Post
All of the bearing issues I’ve seen are from the F30 side, I thought the M2/35 got better spec’d bearings?
All EWG N55s get the S55 rod bearings (and forged S55 rods). The PWG N55s had different bearings and rods which are no longer made and are superceded by the newer S55 rod bearings. The PWG N55s spin their rod bearings way more often. There was definitely as issue with those older rod bearings.
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      08-10-2022, 12:25 PM   #19
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Quote:
Originally Posted by XutvJet View Post
All EWG N55s get the S55 rod bearings (and forged S55 rods). The PWG N55s had different bearings and rods which are no longer made and are superceded by the newer S55 rod bearings. The PWG N55s spin their rod bearings way more often. There was definitely as issue with those older rod bearings.
Source on this? Haven't heard of any bias towards PWG vs EWG N55's.
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      08-11-2022, 07:16 AM   #20
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Quote:
Originally Posted by mwat View Post
Source on this? Haven't heard of any bias towards PWG vs EWG N55's.
It's false, both the F8x, EWG and PWG use the same exact rod bearings.

It even shares the same exact crankshaft connecting rod.

Check it out on realOEM, these are the part numbers based on my car which is PWG.

01 Set connecting rod 1 11247624615

02 Connecting rod bolt M9X47MM 12 11247589671 $4.02
03 Bearing shell yellow 50,00MM(0) 6 11247576714 $1.97
03 Bearing shell violet 50,00MM(0) 6 11247576715 $16.76
04 Bearing shell, red 50,00MM(0) 6 11247628034
04 Bearing shell, blue 50,00MM(0) 6 11247628035


Most of not all spun bearings are due to insufficient oiling, bad maintenance, user error. The reason why it doesn't happen to the S55 is due to their secondary oil pump and essentially integrated baffle. The M2 (N55) as well.
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      08-11-2022, 03:39 PM   #21
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Quote:
Originally Posted by mwat View Post
Source on this? Haven't heard of any bias towards PWG vs EWG N55's.
A ton more PWG N55s have spun their rod bearing than EWG N55s. Look to the E series and F3X series forums for evidence of that. Ask any BMW tech as well. Even better, a simple Google search "bmw n55 rod bearing failure" will tell the story as well. Take note of how many of the reported failures are in pre-2014 N55s which are PWG cars.

The PWG rod bearings were superseded by the rod bearing used in the EWG N55s which came out in the 2014 model year. Only a few BMW SUVs used PWG beyond 2014.

You can see all of this information on RealOEM and see where the part numbers were superseded. That is why "chaungo" thinks his 2013 335i has the 2014+ rods and rod bearings.
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      08-11-2022, 07:21 PM   #22
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Quote:
Originally Posted by XutvJet View Post
A ton more PWG N55s have spun their rod bearing than EWG N55s. Look to the E series and F3X series forums for evidence of that. Ask any BMW tech as well. Even better, a simple Google search "bmw n55 rod bearing failure" will tell the story as well. Take note of how many of the reported failures are in pre-2014 N55s which are PWG cars.

The PWG rod bearings were superseded by the rod bearing used in the EWG N55s which came out in the 2014 model year. Only a few BMW SUVs used PWG beyond 2014.

You can see all of this information on RealOEM and see where the part numbers were superseded. That is why "chaungo" thinks his 2013 335i has the 2014+ rods and rod bearings.
Stop giving false information, everything in realOEM is up to date to your VIN number.

My PWG has essentially 180k miles, so again, rod bearing failures are due to user error, improper maintenance, or insufficient oiling, not rod bearing type.

They use the same bearing, it even tells you the date on when the supersede came into effect, which was from 07/01/2011 for yellow and violet, 11/02/2011 for red and blue.
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