[CleanISH]

I would just like to shed some light to clear up the confusion I see on these forums regarding the N55 motor. First things first the problem that I faced with my 11/12 build date 335i. I was lightly driving the car on the highway for around 100 miles, the knock was not present before getting on the highway. No pulls or excessive acceleration was done during this highway travel. When exiting the highway I noticed a faint knocking noise from rpm range 2k-3k that was barely noticeable while inside of the vehicle. Based off of other platforms I have worked on that have spun bearings I knew immediately that this N55 was done for. The status of the vehicle of time of failure.

- 71k Fresh BMW LL01 0w-40
- VRSF Catless DP
- VRSF CP
- CTS 7" FMIC
- BMS Intake
- MHD Stage 2+

Now lets state the obvious here just so nobody trolls this thread with the "its modded" with the attempt to discredit this thread. When modding ANY platform it is important to understand the risk you are taking, you are pushing the vehicle past its recommended limits. That being said these OTS tunes that 90% of actives on this forum are running (MHD, JB4, BM3.. etc) are not extremely aggressive tunes and in my opinion have zero correlation to bearing failure. For those that are running Custom Tunes from ANY tuner no matter their experience / reputation that are extremely aggressive (excessive timing, excessive boost) everything I'm stating in this post goes out the window. Big boost = Big boom, its just a matter of when no matter what platform you are modding.

Back to my N55. After hearing the knock i did not care about the status of the motor and continued to drive it. Once you hear knock the motor is done in my opinion, once shavings are present in the motor a simple bearing swap and crank hone will not save your motor. This is a band aid fix and in most cases you will run into this issue again. Now a complete rebuild and flush with a good engine builder is another story. I put another 200 miles on this motor before pulling it out and inspecting the damage done. As expected Cylinder 1 spun bearing. The damage done was not extreme in any shape or form... light Scoring/Discoloration of the crank and rod cap and minor shavings located in the oil filter, none jammed up in the oil pickup. Car ran and drove just fine minus the obvious knock from 2k-3krpms and the logs look perfectly normal (I was literally trying to get it to throw the rod).

Let me throw my 2C on why this happens to the N55/N54 platforms. Throwing away the obvious here watered down oil whether it be with coolant OR gas, low oil level (if your N55/N54 is low on oil and it blows there is nobody to blame for that but yourself), and FOD getting into oil galleys. All three of these "reasons" for the N5x platform spinning bearings is not a specific issue to this motor and will cause ANY motor to blow up. The oiling system on the N55 features a wet sump, with no baffling in the oil pan to stop sloshing of oil besides a standard windage tray. This is simple math here for the N5x (not counting the M series with dry sump applications)... High G's + oil slosh + no baffle in the oil pan + wet sump = an EXTREMELY high chance of starvation. Now add in a low oil level condition and you have yourself the perfect storm. Just to clear up all of the confusion in threads related to this for the N5x platforms, this is NOT a BMW issue. No matter what platform you go to if there is a similar oiling system to the one I just described the chances of wrapping a bearing (rod or crank) is increased!!! My suspicion for my blown up motor is that either cylinder one starved under G's, or my oil got watered down in some shape or form (wont know until Blackstone sends the analysis).

With that out of the way lets get onto the fix here. You really have three options depending on the state of your blown up motor.

1) rebuild your existing block
2) get a remanufactured block from you know where (if you like gambling take this route)
3) get a donor motor from a running vehicle that you can VERIFY mileage on and can get a Warranty

I chose the third avenue here, finding a decent motor was difficult but not impossible. It took me about a week to locate one that I was willing to run. Now you need to replace or anything you cannot disassemble and verify that there are no shavings / chunks of bearing material in. For me the list was this.

- Oil Cooler
- Oil Cooler Lines
- Turbo Feed
- Turbo Drain
- Oil Filter Housing (ill cover this at the end)
- Oil Cooler Housing

Now for what everyone wants to hear... what is this going to cost me / how much effort will it take to do this myself???? I spent 5K on the donor motor with 50K and a Warranty, new Flywheel / Clutch (SPEC Stage 2+ & SMFW), various gaskets, and bolts ran me a total of $8100. I pulled the blown up motor out of the car in 8 hours, swapped everything over in 3 hours, and spent 9 hours getting it back in. Compared to other platforms I have pulled motors from the 6MT RWD F30 335i was EXTREMELY easy and can be done WITHOUT a lift. X-drive will add a little more time due to the front axles needing to be pulled. Working on it here and there for 5 days I had the old motor out, the new one in and running with zero codes . Say you cant do this any you need to bring it to a shop, I'm assuming you'd pay around 4k-5k in labor (here in CT). You can sell your Blown up block to the company that makes remanufactured blocks (located in the US) for $1500 to help make some money back.

The infamous Oil Filter Housing that seems to plague these N5x threads. If you are doing this in your car DRAIN COOLANT AND OIL BEFORE HAND. This will greatly decrease the chance of anything getting washed into the oil galleys when removing it. Other than that this is just replacing a gasket... I am very unsure why people think this is such a treacherous job to complete. Pop off the Oil filter housing and the oil cooler housing, CLEAN everything and inspect the oil galleys in the OFH, OCH, and Cylinder head. If no FOD is found great! Oil the gaskets and torque the bolts TO SPEC. Too tight and the gasket will run out, too loose and the coolant and oil can mix (watered down oil which was covered above). Lastly these are stretch bolts so head on down to BMW or FCP Euro and get new bolts!!!! Before you start the car unplug either the coil packs or injectors and crank the car until it builds oil pressure. Plug everything back in start it up drive the car and every so often pop off the oil filter cap to take a look at the oil condition. If it is not milky chances are your OFHG is not leaking on the inside and you did a good job. If it is milky rinse and repeat.

Time to sleeve the old block, throw in some forged pistons and pair with a PTE 62/66 and see if we can get the N55 guys to compete with the N54 guys

[frchdragon]

Sorry to hear about your misfortune, the crankshaft bearing is what is scaring me on my N55, especially with track season starting.
With a leaking oil pan gasket, the oil pan will have to come off, if the oil pan is off, I might as well take the time to change the rod bearings.

So far, I haven't found a DIY to do the bearings on an N55 engine, anyone has one?

[CleanISH]

Originally Posted by frchdragon

Sorry to hear about your misfortune, the crankshaft bearing is what is scaring me on my N55, especially with track season starting.
With a leaking oil pan gasket, the oil pan will have to come off, if the oil pan is off, I might as well take the time to change the rod bearings.

So far, I haven't found a DIY to do the bearings on an N55 engine, anyone has one?

It’s pretty simple.
1) take off the oil pickup tube
2) un bolt the oil pump & chain
3) pop off each rod cap (do not mix up the rod caps)
4) install new bearings and test oil clearance with plasti-gauge
5) if the clearance looks good clean up the Plasti gauge and reassemble

** do not just slap the bearings in without testing oil clearance.

In my opinion if you change your oil every 4-5k miles and make sure it stays FULL there is no reason to replace the bearings. Besides the spun cylinder #1 all 2-6 looked a okay to me.

[XutvJet]

Unfortunately, the earlier model F series N55s predating 2014 can have rod bearing issues. The 2014+ electronic wastegate (EWG) equipped N55s have the S55 motor connecting rods and rod bearings. The instances of spun rod bearings on the EWG N55s are significantly lessened with those parts.

The EWG N55 in the M235 has an oil cooler and forged crank as stock which the F3X N55s do not have. The M2 N55 (and the M235iR) also use the S55 oiling system. This includes an improved oil pump, pickup, and baffled oil pan for high G driving. The S55 oiling system parts list is below and they can be used on any EWG N55. Lots of M235 owners have made the swap. I'm not sure about the 2013 and below N55s though.

https://www.2addicts.com/forums/show...79&postcount=5

[thejeremyman9]

Originally Posted by XutvJet

Unfortunately, the earlier model F series N55s predating 2014 can have rod bearing issues. The 2014+ electronic wastegate (EWG) equipped N55s have the S55 motor connecting rods and rod bearings. The instances of spun rod bearings on the EWG N55s are significantly lessened with those parts.

The EWG N55 in the M235 has an oil cooler and forged crank as stock which the F3X N55s do not have. The M2 N55 (and the M235iR) also use the S55 oiling system. This includes an improved oil pump, pickup, and baffled oil pan for high G driving. The S55 oiling system parts list is below and they can be used on any EWG N55. Lots of M235 owners have made the swap. I'm not sure about the 2013 and below N55s though.

https://www.2addicts.com/forums/show...79&postcount=5

What do you mean by oil cooler in the M235 that F3X N55 does not have? My car has a oil cooler, unless you mean a different one/different design?

[F32Fleet]

Originally Posted by thejeremyman9

What do you mean by oil cooler in the M235 that F3X N55 does not have? My car has a oil cooler, unless you mean a different one/different design?

I think he means the forged crank only.

[dalderks]

Originally Posted by thejeremyman9

What do you mean by oil cooler in the M235 that F3X N55 does not have? My car has a oil cooler, unless you mean a different one/different design?

IIRC, the M235i has an extra/aux oil cooler behind the passenger headlight (almost underneath the coolant reservoir). I might be misremembering, but I don't think it's there on the F30.

[XutvJet]

Originally Posted by dalderks

IIRC, the M235i has an extra/aux oil cooler behind the passenger headlight (almost underneath the coolant reservoir). I might be misremembering, but I don't think it's there on the F30.

Correct.

[thejeremyman9]

Originally Posted by dalderks

IIRC, the M235i has an extra/aux oil cooler behind the passenger headlight (almost underneath the coolant reservoir). I might be misremembering, but I don't think it's there on the F30.

Are you talking about the one that just looks like a heat sync? I'm pretty sure i have that... Can you post a photo?

[F32Fleet]

Originally Posted by thejeremyman9

Are you talking about the one that just looks like a heat sync? I'm pretty sure i have that... Can you post a photo?

Originally Posted by dalderks

IIRC, the M235i has an extra/aux oil cooler behind the passenger headlight (almost underneath the coolant reservoir). I might be misremembering, but I don't think it's there on the F30.

All F-series 335i have the aux oil cooler which is located in the front passenger side wheel well behind the headlamp

[dalderks]

Originally Posted by thejeremyman9

Are you talking about the one that just looks like a heat sync? I'm pretty sure i have that... Can you post a photo?

Yeah, looks like a heatsink. Here's a photo from my 2014 M235i.

Originally Posted by F32Fleet

All F-series 335i have the aux oil cooler which is located in the front passenger side wheel well behind the headlamp

Gotcha. I seem to remember watching a Kies video installing something (inlet pipe maybe?) and I don't remember it being there.

Seeing this thread does make me think about making the oil pan and sump modifications before hitting the track this year.

[thejeremyman9]

Originally Posted by dalderks

Yeah, looks like a heatsink. Here's a photo from my 2014 M235i.



Gotcha. I seem to remember watching a Kies video installing something (inlet pipe maybe?) and I don't remember it being there.

Seeing this thread does make me think about making the oil pan and sump modifications before hitting the track this year.

Originally Posted by F32Fleet

All F-series 335i have the aux oil cooler which is located in the front passenger side wheel well behind the headlamp

Yup, i have that on my 2015 335i. So i don't think the M235 has any different oil cooling system than F3x, at least with my specs.

[14F30Daily]

I have that on my 14 335i as well. Could that be for the M-sport line?

[GAB0]

I have it on my 13 335I (M-Sport) as well.

[F32Fleet]

Originally Posted by GAB0

I have it on my 13 335I (M-Sport) as well.

Originally Posted by 14F30Daily

I have that on my 14 335i as well. Could that be for the M-sport line?

M-sport line has two auxiliary coolers (Oil & Coolant).

All 335i have an oil cooler.

[F32Fleet]

Originally Posted by dalderks

Yeah, looks like a heatsink. Here's a photo from my 2014 M235i.

Gotcha. I seem to remember watching a Kies video installing something (inlet pipe maybe?) and I don't remember it being there.

Seeing this thread does make me think about making the oil pan and sump modifications before hitting the track this year.

Originally Posted by 14F30Daily

I have that on my 14 335i as well. Could that be for the M-sport line?

That is the heat exchanger not an oil cooler.

Oil cooler is located in passenger side front wheel well. On M-Sport line cars you can also see it from the bumper.

[JaredG_F30]

I have a 2014 EWG M-sport so not toooooo concerned but the next time I have to change my oil pan gasket I'd like to upgrade to a baffled oil pan. I think Turner makes one, maybe a few others out there. Regardless I'm getting my bearing changed at 100k miles as I do occasionally track the car.