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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > N55 rod knock/spun bearing tracking



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      07-18-2018, 03:20 PM   #45
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Quote:
Originally Posted by Pladi View Post
again you are missing the point.. You have a headache you take Tylenol and no more headache you are not dealing with the root cause. Your headache will return. If you know for sure that the bearings are bad thats when you do that type of work.. who here has proved that. So replacing bearings "proactively" does not necessarily solve the root cause. Your new bearings will have the same potential of failure if you have not dealt with the root cause..
I'm just saying that replacing rod bearings is not that complicated.

I don't think there is any root cause, just because you have a few guys who have spun bearings on modified cars doesn't mean there is an issue with the engine, there are a shit ton of variables. There were thousands upon thousands of N55's produced so these failures are a non issue as you have no data to indicate that any of them are related to one failure mode.
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      07-18-2018, 03:23 PM   #46
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Quote:
Originally Posted by bbnks2 View Post
I see BMW spec'd these motors for rod bearing clearances of .00135". Most engine builders would spec a 20wt oil for that tight of a tolerance... S65 engines have the same type of pre-mature bearing wear with the same tight clearance spec and they change their bearings every 60k as a preventative measure. BMW is now putting 30wt oil into those motors vs their old recommendation of 60wt.

I think this may become a future recommendation with N55 motors too... Many engine builders are grinding down cranks and running .002" - .003" rod bearing clearances which is better suited to 40wt oils and high load engines. We very well could be seeing intermittent oil starvation causing bearing wear over time. Particularly, in left hand sweepers. Once the bearing get's worn down past its hard out layer, which we have seen plenty of motors show bearings down to the copper, they will over-heat and melt to the crank. Not much you can do about oiling except maybe run a thinner oil, but you can surely polish the crank and throw in new bearings in a few hours as a maintenance thing for <$150.

Changing rod bearings is not rocket science. I think we would see 100x more engines have this work done if it didn't involve so much work to get the oil pan off. Once the pan is off all you have to do is remove the rad caps and swap the bearings. There is nothing to "get wrong" except mixing up the rod caps or something. The only reason why rod bearing clearance would be out of spec is because you have a rotating assembly problem. This is hardly something someone swapping rod bearings should encounter, but it would damn nice to catch an out of spec rotating assembly before a seized motor!
The tight bearing clearance is the reason i never anymore use weight 40 on this motor. Even if replacing the rod bearings is not that much work in my opinion its not worth any risk if you have a working engine..

But please someone do it id love to see the results.
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      07-18-2018, 03:31 PM   #47
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Quote:
Originally Posted by 9krpmrx8 View Post
I'm just saying that replacing rod bearings is not that complicated.

I don't think there is any root cause, just because you have a few guys who have spun bearings on modified cars doesn't mean there is an issue with the engine, there are a shit ton of variables. There were thousands upon thousands of N55's produced so these failures are a non issue as you have no data to indicate that any of them are related to one failure mode.
Yes i could not agree more. I I have said this on the other thread. Hence why i also say that this "preventative maintenance" work is not necessary. Unless you knew your car was assembled at a location that has put "wrong bearings" " bad torque" etc..
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      07-18-2018, 03:47 PM   #48
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Quote:
Originally Posted by Pladi View Post
The tight bearing clearance is the reason i never anymore use weight 40 on this motor. Even if replacing the rod bearings is not that much work in my opinion its not worth any risk if you have a working engine..

But please someone do it id love to see the results.
Why don't you used weight 40? I just changed my oil to 0w40 castrol edge. It said it was LL01 approved so I figured it would be fine. How does the weight potentially effect bearing wear? I'm a bit of a car noob.
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      07-18-2018, 04:10 PM   #49
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LL01 means nothing unless you are following factory oil change intervals. 0W-40 is fine, I have been using M1 0W-40 since day one and have have it tested a couple of times a year and at 95k my test result still look fine.
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      07-18-2018, 04:25 PM   #50
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Quote:
Originally Posted by bbnks2 View Post

Changing rod bearings is not rocket science. I think we would see 100x more engines have this work done if it didn't involve so much work to get the oil pan off. Once the pan is off all you have to do is remove the rad caps and swap the bearings. There is nothing to "get wrong" except mixing up the rod caps or something.
There are certainly things you can get wrong. In order to do it properly, you'll need a Plastigauge to start. You'll have to follow the tolerances required by the factory.

Replacing rod bearings itself is not a mechanically difficult task, but like painting, it requires a lot of prep work and measuring. That's where most mistakes happen.

https://www.newtis.info/tisv2/a/en/e...rings/Cz2CUvNY
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      07-18-2018, 04:42 PM   #51
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bbinks took it exactly where I was going with this discussion. I agree that oil starvation over time may, for Pladi... MAY, be resulting in premature bearing wear. Lets be real, most likely it is. And isn't that what typically causes this condition? Several reasons were given. Among them thicker original "recomended" oil, which was hinted at may not flow as well in engines with uber tight clearances. Glad I am running 5 - 30.

Another reason is fuel in the oil, thus on a momentary basis keeping oil from lubricating the moving components ala leaky N54 fuel injectors. I initially ran a Dinan stage 3 tune, which I was told was too rich. In this condition how much fuel actually ends up in the oil versus out the exhaust? And if any ends up in the oil, how much is too much? On the excel sheet I noticed different power levels. The 500 + hp guys no doubt worked their way up. Early on could they have had a rich condition that led to slight wear that over time progressively got worse until... bang. The guys at the lower power levels just may have been in a rich condition longer period of time before they could tweak the AFR properly. Not saying this is it, but as it isn't just engines built way up, is this Pladiable?

I brought up cold ambient temperatures since we all know when it is real cold the viscosity thickens. I have lived in the south for 40 years now, but when up north I recall oil heaters. If very cold starts can not possibly cause engine damage, why did the device exist in the first place? My bringing up proactively changing them out is not for the hell of it. It is because they don't go from perfect working condition to the point where they spin overnight. Agreed that a result of an oil test would indicate if such a measure may be necessary. Sorry, but if there is copper in my oil I won't be waiting around until someone finds out the root cause of why it got there before taking action. This seem to be occurring on 2011s so far. I'd consider 9 of the same year engines only, as a trend. Provided the clearances are the same with later N55s I'd have to believe that this may be as simple as an issue with the material used in the sintering process. Something that BMW absolutely would never ever admit to. Changing out said bearings that in an oil test indicates appear to be failing with newer ones may minimize the risk / exposure. I have no idea how to reference this, but are the part numbers for rod bearings for a 2011 and a 2012 the same? If different, why?
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      07-18-2018, 04:49 PM   #52
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Quote:
Originally Posted by bbnks2 View Post
I see BMW spec'd these motors for rod bearing clearances of .00135". Most engine builders would spec a 20wt oil for that tight of a tolerance... S65 engines have the same type of pre-mature bearing wear with the same tight clearance spec and they change their bearings every 60k as a preventative measure. BMW is now putting 30wt oil into those motors vs their old recommendation of 60wt.
Where are you seeing/hearing this in regards to 30 weight being used in the S65? We have never put anything other than the recommended BMW branded 10W-60 in the S54, S65, S85, and some S62s. We also still use 5W-30 in everything else up to halfway through 2017 model year cars. The 2017 and a half+ model year cars use 0W-20 and 0W-30.
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      07-19-2018, 08:28 AM   #53
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Guys BBNKS2 brings up excellent points. I personally started researching about the two approved weights 30 and 40 about a year ago. And pretty much came to the conclusion that the 30 weight is better for tight tolerance engines for obvious reasons. A good 30 weight oil with the good additive package will surpass 40 weight in shear protection. Not to mention it flows better and provides good cooling. Now do i think someone who is using 40 weight will have issues ? No i cannot say that. All i believe is that 30 weight is better suited for this engine. It just makes sense. No scientific experiments to back up...

I was sold with BMW 5W-30 weight after watching this test. The same guy tests many 40 weight oils including 5W-40 form liqui moly. The BMW test surpasses most tests he has done over 100..

That is a simple test but very meaningful test.

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      07-19-2018, 08:38 AM   #54
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Quote:
Originally Posted by Ozzie335i View Post
bbinks took it exactly where I was going with this discussion. I agree that oil starvation over time may, for Pladi... MAY, be resulting in premature bearing wear. Lets be real, most likely it is. And isn't that what typically causes this condition? Several reasons were given. Among them thicker original "recomended" oil, which was hinted at may not flow as well in engines with uber tight clearances. Glad I am running 5 - 30.

Another reason is fuel in the oil, thus on a momentary basis keeping oil from lubricating the moving components ala leaky N54 fuel injectors. I initially ran a Dinan stage 3 tune, which I was told was too rich. In this condition how much fuel actually ends up in the oil versus out the exhaust? And if any ends up in the oil, how much is too much? On the excel sheet I noticed different power levels. The 500 + hp guys no doubt worked their way up. Early on could they have had a rich condition that led to slight wear that over time progressively got worse until... bang. The guys at the lower power levels just may have been in a rich condition longer period of time before they could tweak the AFR properly. Not saying this is it, but as it isn't just engines built way up, is this Pladiable?

I brought up cold ambient temperatures since we all know when it is real cold the viscosity thickens. I have lived in the south for 40 years now, but when up north I recall oil heaters. If very cold starts can not possibly cause engine damage, why did the device exist in the first place? My bringing up proactively changing them out is not for the hell of it. It is because they don't go from perfect working condition to the point where they spin overnight. Agreed that a result of an oil test would indicate if such a measure may be necessary. Sorry, but if there is copper in my oil I won't be waiting around until someone finds out the root cause of why it got there before taking action. This seem to be occurring on 2011s so far. I'd consider 9 of the same year engines only, as a trend. Provided the clearances are the same with later N55s I'd have to believe that this may be as simple as an issue with the material used in the sintering process. Something that BMW absolutely would never ever admit to. Changing out said bearings that in an oil test indicates appear to be failing with newer ones may minimize the risk / exposure. I have no idea how to reference this, but are the part numbers for rod bearings for a 2011 and a 2012 the same? If different, why?
My personal theory is that "KNOCK" is destroying these bearings. These engines have corrections on stock maps of up to 3 degrees per cylinder. Do that over and over and over you are bound to cause mechanical stress. This is with recommended 91 octane gas. Ad to that tunes and more boost.. more knock. If you notice almost all engines that saw issues had some sort of tune running. So i personally think that you have to do absolutely everything to keep the corrections down, is the way to go to protect this engine.
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      07-19-2018, 09:13 AM   #55
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Quote:
Originally Posted by SnapCoupe View Post
Where are you seeing/hearing this in regards to 30 weight being used in the S65? We have never put anything other than the recommended BMW branded 10W-60 in the S54, S65, S85, and some S62s. We also still use 5W-30 in everything else up to halfway through 2017 model year cars. The 2017 and a half+ model year cars use 0W-20 and 0W-30.
Per BMW any ll-01 is good for the s65
https://www.m3post.com/forums/attach...4&d=1381119577

I could be wrong, but I personally believe you're better off with a ll-01 30wt than a ll-01 40wt. Both will have a high hths rating of 3.5cP but the 30wt will flow better. Bearing clearances are what they are... .00135" is a very tight tolerance and BMW seems to be using it on all their motors. Why do they use 0-20 in new motors and 10-60 in older motors when they both have the same tolerances? I'm asking... If you Google you will find that 20-30wt is what is recommended for these specs. Maybe BMW knows a bit more about oiling their motors than I do though lol I would definitely like to hear the logic!
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      07-19-2018, 10:36 AM   #56
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      07-19-2018, 12:29 PM   #57
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Quote:
Originally Posted by bbnks2 View Post
Per BMW any ll-01 is good for the s65
https://www.m3post.com/forums/attach...4&d=1381119577

I could be wrong, but I personally believe you're better off with a ll-01 30wt than a ll-01 40wt. Both will have a high hths rating of 3.5cP but the 30wt will flow better. Bearing clearances are what they are... .00135" is a very tight tolerance and BMW seems to be using it on all their motors. Why do they use 0-20 in new motors and 10-60 in older motors when they both have the same tolerances? I'm asking... If you Google you will find that 20-30wt is what is recommended for these specs. Maybe BMW knows a bit more about oiling their motors than I do though lol I would definitely like to hear the logic!
They only use the 0W-20 and 0W-30 in motors that would've used 5W-30. I have been told that the reason behind this change was for temperature and climate variables. BMW only used 10W-60 in the high revving NA cars, which were replaced by the turbo motors that first started off using 5W-30. From the BMW techs I have worked with over the years, it seems the general consensus was that the 10W-60 just works better at higher revs (S54, S65, S85).

My Z4M coupe had 10W-60 oil changes every 12k miles up to 80k miles before I took ownership of it, then I shortened the interval to 8k between changes. At 105k I adjusted the valves and had to pop the motor open. It looked brand spanking new inside.
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Last edited by SnapCoupe; 07-19-2018 at 05:06 PM.
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      Yesterday, 06:55 PM   #58
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My build date is 10/10 so this is pretty anxiety inducing lol
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